C-Tek battery charger and fridge conflict

Submitted: Saturday, Sep 14, 2013 at 16:25
ThreadID: 104320 Views:5999 Replies:11 FollowUps:50
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We recently fitted our Ultimate camper with a C-tek battery charger which works well when the fridge is not on, however when the Dometic 3 way fridge is turned on there is a conflict and the battery does not charge. Has anyone come across this problem and is aware of a fix. We currently get around this by connecting the fridge with a small battery while we recharge the main battery but would appreciate a more permanent solution.
Thanks
Chris
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Reply By: Keir & Marg - Saturday, Sep 14, 2013 at 16:39

Saturday, Sep 14, 2013 at 16:39
Chris - could you advise what C-tek charger you are using? If the Dometic 3-way is being used on 12volts, it will draw about 15 amps, and if your charger can't supply at least that, the battery will still be discharging. If the C-tek is being used on 240V (I think all C-tek chargers except the D250S are 240V), then just run your fridge on 240V (or gas) instead of 12V whilst you are re-charging the main battery.
Cheers, Keir
AnswerID: 518134

Reply By: KenInPerth - Saturday, Sep 14, 2013 at 16:42

Saturday, Sep 14, 2013 at 16:42
Chris

Can you post some more info - the model of the Ctek charger, the fridge, the battery size and type, and how flat the battery would be when you go to charge it.

I might be way off the mark, but it may be that when the fridge is either connected or when it first cuts in and runs the charger may be seeing it as a "bad battery" taking too much current and shutting down the charging output - perhaps very much dependent on the Ctek model you have.

I run a Ctek D250S Dual which charges battery and a 40l Evakool portable fridge without any trouble, but I am guessing you may have a mains charger.

The added info will help others give a more informed answer.

Ken
AnswerID: 518135

Follow Up By: olcoolone - Sunday, Sep 15, 2013 at 10:11

Sunday, Sep 15, 2013 at 10:11
Difference with you fridge is it draws 3-5 amps when running and will cycle, three way fridges draw 15-20 amps constant and will not cycle.

On a 100 amphour battery if fully charged you could get is lucky 4-5 hours runtime on a three way.

Someone has wired OZYCHRIS's camper and Ctek up wrong.
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Reply By: ozychris - Saturday, Sep 14, 2013 at 17:39

Saturday, Sep 14, 2013 at 17:39
I will check which model C-tek is installed on Monday. The problem occurs when the fridge is running on gas or 240V. The fridge requires a 12 V input at all times to run the control system. If I connect the fridge to a small 12V battery that I use for my fish finder the problem goes away and the charger charges the house battery as normal. An auto electrician that I talked to in Townsville said he had seen the problem before but was not aware of a fix. It appears there is a conflict between the electronic managment system and the charger. Thanks to all for your assistance. Chris
AnswerID: 518139

Follow Up By: oldtrack123 - Sunday, Sep 15, 2013 at 00:16

Sunday, Sep 15, 2013 at 00:16
Hi
You appear to have an AES model fridge

These do require a permanent 12V supply from the van battery TO OPERATE the very low current draw control system

The 12V Heater should NEVER be connected to the van battery or the battery side of a DC TO DC charger [if that is the Ctek model you have]The HEATER CIRCUIT SHOULD ALWAW BE CONNECTED TO the CRANK battery by heavy cables

Trying to supply a high current load such as the 12V heater of almost any 3way fridge will leave very little power oooover to charge the van battery
BUT an additional probelm occurs if the supply cables are inadequate especially within the van [as they usually are]
The required voltage to fully charge the VAN battery is not available AT THE VAN battery
I would also suggest the installer of your fridge did not KNOW how to install to the makers recommendations
Which clearly defines TWO seperate circuits are required
[a] one circuit[ small cables] permanently connected to the van battery &he 12V control terminals of the fridge
[b] Another circuit, HEAVY cables no smaller than 6B&S , right through friom the fridge heater circuit terminals to the vehicle battery!!
]
PeterQ
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Follow Up By: olcoolone - Sunday, Sep 15, 2013 at 10:12

Sunday, Sep 15, 2013 at 10:12
OLDTRACK........ is on the right track, what he has said is spot on.
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Reply By: Dennis Ellery - Saturday, Sep 14, 2013 at 17:58

Saturday, Sep 14, 2013 at 17:58
There is something wrong with your fridge if you need 12volt to operate it while on gas or 250 volt.
The way your camper is wired is not good practice.
There should be no connection from fridge to the caravan battery.
The standard way to connect a 3 way fridge is to have a separate dedicated line from car battery to caravan fridge. Then when stopped the fridge needs turning to gas to avoid flattening the car battery.
AnswerID: 518142

Follow Up By: Ozhumvee - Saturday, Sep 14, 2013 at 18:31

Saturday, Sep 14, 2013 at 18:31
Dennis I'm sorry to say that the later model dometics have an electronic front end control system and unless they have a good 12v connection they will not work on 240, gas or 12v.
We have a dometic fridge in a slideon camper and if the 12v battery isn't connected she no go.
Peter
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Follow Up By: Nomadic Navara - Saturday, Sep 14, 2013 at 19:10

Saturday, Sep 14, 2013 at 19:10
Quote " There is something wrong with your fridge if you need 12volt to operate it while on gas or 250 volt."

If the fridge is an AES (automatic energy select) there is a control board in the fridge that requires a small 12 V suply fom your house battery at all times. AES fridges have 2 12 V inputs, one from the house battery and one from the alternator. The input for the alternator supply should never be wired to your house battery.

Please check facts before posting.
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Follow Up By: Dennis Ellery - Saturday, Sep 14, 2013 at 22:25

Saturday, Sep 14, 2013 at 22:25
Hi Peters (Ozhumvee and Nomadic Navara)
You’re both stroppy old sods.
I don’t have an automatic energy select fridge. Just the bog standard manual 3 way Dometic, 2008 model, common to a most caravans I have seen. My reply is accurate for that type of fridge.
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Follow Up By: Nomadic Navara - Saturday, Sep 14, 2013 at 23:00

Saturday, Sep 14, 2013 at 23:00
Dennis, You made the bald statement "There is something wrong with your fridge if you need 12volt to operate it while on gas or 250 volt." You did not state that you were only talking about your type of absorption fridge. The OP sounds like he has an AES fridge, that made your statement completely erroneous in the context of this thread. I think you are the "stroppy old sod."

AES fridges need a constant source of 12 V power to work at all times if they are to work correctly. Without it the logic circuitry will not switch between energy sources.

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Follow Up By: Ozhumvee - Sunday, Sep 15, 2013 at 08:10

Sunday, Sep 15, 2013 at 08:10
To tell the truth it is probably a nail in the coffin of the old three way fridges as the need for 12v (about 11.5 minimum in my experience) is a PITA especially if leaving the unit sitting even for a few days without charging is impossible unless you have a huge battery fitted.
We found with our slideon that if left sitting without AC power to charge it you got a max of 36 hours runnning on gas, less if the fan assist was on with a typical 55ah battery.
It meant that in warm weather if we parked at a hotel for a few days in a city and there was no AC available we had to empty the fridge which again was a big PITA.
Peter
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Follow Up By: oldtrack123 - Sunday, Sep 15, 2013 at 14:03

Sunday, Sep 15, 2013 at 14:03
HI Peter
A 3way has never been intended to run on 12V, unless the engine of the vehicle is running a suppling sufficient power from the ALTERNATOR
The gas operation is for use , when 12V from that source or 240V MAINS power is not available!
Perhaps users, people ,& INSTALLERS SHOUD READ the supplied manuals


PeterQ
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Follow Up By: Ozhumvee - Sunday, Sep 15, 2013 at 14:11

Sunday, Sep 15, 2013 at 14:11
PeterQ
I was talking about leaving it running on gas not 12v.
I suggest that but putting an electronic front end that MUST have a good 12v supply to enable it to run on gas is a big step backward IMHO.
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Follow Up By: Dennis Ellery - Sunday, Sep 15, 2013 at 19:48

Sunday, Sep 15, 2013 at 19:48
Hi Oldtrack it’s a common problem – You wouldn’t believe the number people I struck in my travels, with stuffed batteries due to running their 3 way fridges running off the caravan battery.
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Follow Up By: oldtrack123 - Sunday, Sep 15, 2013 at 23:13

Sunday, Sep 15, 2013 at 23:13
Quote"Ozhumvee posted:
PeterQ
I was talking about leaving it running on gas not 12v.
I suggest that but putting an electronic front end that MUST have a good 12v supply to enable it to run on gas is a big step backward IMHO[end quote]

Hi
The actual current draw of the electronic control module is not high
[only around 400 milliamps from memory] so does not have much effect on battery usage.
It just requires a PERMANENT 12V supply
But the same size fridges are also available in manual select& ignige, if one does not WANT an AES type.

PeterQ
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Follow Up By: oldtrack123 - Sunday, Sep 15, 2013 at 23:30

Sunday, Sep 15, 2013 at 23:30
HI Dennis
I can well believe it
It will continue for as long as people get the wrong advice saying:
[1] it is ok to run a 3way on 12V from the house battery
[2]That a DC to DC charger to charge the house battery & run the fridge on 12V will work fine
[3] for as long as Van makers & fridge installers do not understand even the basics of voltage drop & it's efects & install undersized cables for the lengths involved
[4]
[a]ALL of which adds up to ,ONLY RUN YOUR 3 WAY on 12V from the vehicle battery
[b]ALWAYS have an isolator of some type in the fridge heater circuit which disconects the fridge heater when the vehicle engine is not running
Some model fridges have this built in BUT that requires a seperate wire to the D+ terminal of the alternator

But again many installers do not even understand THAT.

One often ends up with the 12V control, the 12V heater & the voltage sense[D+] leads ALL commoned & connected to the house battery!!!


YES, i have a poor opinion of many of those involved in wiring vans motor homes etc
But often it simply because they are not trained electricians!& know no better

PeterQ
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Reply By: Member - John and Val - Saturday, Sep 14, 2013 at 18:22

Saturday, Sep 14, 2013 at 18:22
Chris,

You should not run the fridge on 12V unless the engine is running and sending charge to the trailer. A 3 way fridge draws 12-15 amps when running on 12V, and no charger will supply this much and also charge the battery properly. When stationary, the fridge should be run on gas.

Sorry - that's one of the facts of travelling life with a 3 way fridge. A compressor fridge can be run from batteries for extended periods, but not a 3 way.

Cheers

John
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Reply By: Member - Phil G (SA) - Saturday, Sep 14, 2013 at 18:34

Saturday, Sep 14, 2013 at 18:34
Chris,
My recollection about the factory Ultimate setup is that the fridge remains connected to all 3 power sources. It pulls from the 240V preferentially then from the 12v source if voltage is above a level that indicates charging from the alternator and then starts up the LPG if the first 2 are not present.
Ultimate will also fit a CTek charger which I think is 25 amp which obviously kicks in when the Ultimate is plugged in.

Given that you've fitting the Ctek yourself' my guess is that your Ctek is not wired up the same as the factory setup or the Ctek is not big enough.

You'll have to ask the same question on the Ultimate forum as the Ultimate owners know this much better that me.
AnswerID: 518145

Follow Up By: olcoolone - Sunday, Sep 15, 2013 at 10:06

Sunday, Sep 15, 2013 at 10:06
The Ultimate has an ignition trigger wire in the 12 pin factory plug that controls a simple 4 pin relay that switches the 12 volt feed from the car when the ignition is on, it sounds like someone has wired it up for the all the power including the fridge and charging the batteries through the Ctek........ the fridge and ctek should be separated and be tee'd off from the vehicle feed to form two separate circuits.

1) to the Ctek to charge batteries. 2) to supply power to the fridge when on 12v from the vehicle.

Typical thing we see with DIYers not understanding something and is very common in caravan and camper trailers..... not having a go at DIYers but some need to learn and ask questions before attempting somethings and understand the reasoning behind the concept.

The original factory Ultimate wire was done by someone who had little understanding or foresight.

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Reply By: Nomadic Navara - Saturday, Sep 14, 2013 at 19:17

Saturday, Sep 14, 2013 at 19:17
Chris, it sounds like you have an AES fridge and it is wired incorrectly (a common problem when fridges are wired by 50 Hz electricians who don't read or understand the instructions.)

There are a few different models of AES fridges so I can't quote the exact wiring instructions. However they all have a low current 12 V input for the control circuitry and another high current input from the alternator.

If you had have given the model number we could have given you the correct info.

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Reply By: Member - LeighW - Sunday, Sep 15, 2013 at 17:56

Sunday, Sep 15, 2013 at 17:56
Hi ozychris,

Seems people just don't bother reading things or see what they want to see!

You wrote that if you power the fridge from a small battery when on gas etc that the ctek will then fire up and charge the main battery.

This implies that isolating the fridge controller allows the ctek to work properly, as the controller of the fridge is only drawing a small amount of current under this conditioning it can't be an overload condition stopping the charging.

Possibly some sort of induced RF interference from the fridge controller upsetting the ctek?

You could try putting a ferrite trap available from Jaycar on the power supply cables to the fridge as this should stop any possible interference from the fridge controller feeding back via the power cables to the ctek.

Cheers
Leigh

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AnswerID: 518201

Follow Up By: ozychris - Sunday, Sep 15, 2013 at 18:26

Sunday, Sep 15, 2013 at 18:26
Thank you for actually reading our problem.
Your reply sounds like a good idea, we will try that tomorrow.
Cheers
Chris
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Follow Up By: Travis22 - Sunday, Sep 15, 2013 at 23:31

Sunday, Sep 15, 2013 at 23:31
LeighW is on the right track IMO.

I remember reading something a while back on one of the South African offroad forums and a member there had the same sort of problem. When he had something connected to the battery it was interfering with the Ctek and it would not begin charging.

I would suggest possibly calling the technical guys at Baintech in QLD, they are the most knowledgeable people regarding Ctek in Australia as far as i can tell. I think they are the distributors, and they are the service agents for Ctek (I had a faulty 15A Ctek which they tested and replaced under warranty a couple of years ago).

http://www.baintech.com.au/contact-us

Im not sure but it might be as simple as a diode on the low current fridge supply??
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Follow Up By: oldtrack123 - Sunday, Sep 15, 2013 at 23:39

Sunday, Sep 15, 2013 at 23:39
HI Leigh
If the fridge load causes the battery voltage to drop, the DC to Dc charger will of course try to charge the battery
IT SENSES THE BATTERY IS UNDERCHARGED

That is another reason the FRIDGE heater should never be connected to the house battery
.
The heavy load will give a FALSE indication of SOC to ANY CHARGER!

It can even lead the the battery being held for long periods at the gassing stage ,due to charge controller not sensing enough voltage to move to the next stage
[SHORT BATTERY LIFE]

PeterQ
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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 09:09

Monday, Sep 16, 2013 at 09:09
PeterQ

You are missing the point, try reading the original post, the problem is the ctek won't charge the battery with the fridge connected no matter what the fridge is set for ie 12V, gas or 240V.

It won't charge!

If he disconnects the fridge supply from the main battery and connects it to a small battery the fridge continues to work ok on gas etc.

With the fridge disconnected the ctek will then fire up and charge the main battery. So much for your theory of the load starting the charger, he has disconnected it!

I would be surprised if the fridge even running on 12V would cause the ctek to overload as a discharged battery could draw more than 20A and I would assume the ctek is current limited at 20A to overcome this issue.

If you had bothered to read the original post you would have noticed he is running the fridge on GAS! and 240V! with the same result, not 12V so the 12V heater does not come into the equation!..

Cheers
Leigh

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Follow Up By: Travis22 - Monday, Sep 16, 2013 at 09:29

Monday, Sep 16, 2013 at 09:29
As Leigh has said once again this has nothing to do with the state of charge of the battery or the imposed load the fridge is putting on the battery!!!!!

It is electrickery! The ctek charger will do a very quick analysis of the battery to check it is ok before beginning the charging stages, something in the fridges circuitry is interfering with the ctek and it will not begin charging.

Ive been lucky in that our Fridge, camplights and 240v inverter have never interfered with out 15a ctek but 99% of the time i disconnect them anyways when the batteries are connected to the ctek.

The ctek is fine, your batteries are fine and the fridge is fine its just interference. Id bet you could run a 'dumb' charger and it would work fine its just the ctek being to smart lol.

Another option could be to try temporarily disconnecting the fridge and allowing the ctek to get into the bulk or absorption stage then plug the fridge back in?

Travis
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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 09:31

Monday, Sep 16, 2013 at 09:31
I before you start again, yes the fridge shouldn't be run on the battery whilst it's being charged but that's the way it has been wired.

Interestingly from what I have read Ctek state that it is ok to have a load connected whilst the battery is being charged.

Cheers
Leigh

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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 09:33

Monday, Sep 16, 2013 at 09:33
Above is in reply for PeterQ

Cheers
Leigh

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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 11:25

Monday, Sep 16, 2013 at 11:25
HI Leigh

Perhaps you should reread the OP post but for your information
here it is :
[QUOTE"We recently fitted our Ultimate camper with a CTEK BATTERYCHARGER ,WHICH WORKS WELL WHEN THE FRIDGE IS NOT "ON"

HOWEVER WHEN THE FRIDGE IS TURNED "ON" THERE IS A CONFLICT and the battery does not charge. Has anyone come across this problem and is aware of a fix. We currently get around this by connecting the fridge with a small battery while we recharge the main battery but would appreciate a more permanent solution.
Thanks
Chris[end quote}

Every thing in THAT post Indicates it is the load of the fridge causing the problem
The problem would be as I have indicated


I would strongly suggest to Chris, that he does some very simple tests:
[1]FIRST DISCHARGE THE HOUSE BATTERY TO SAY 12.5V ie so it requires charging
[2]with the fridge not switched on, but engine running at medium to fast idle [Ctek charging the house battery] CHECK THE VOLTAGE AT THE HOUSE BATTERY
[3]Then immediately turn the fridge on to 12V operation & RECHECK the voltage AT the HOUSE battery

[4]Report your results here
I will predict that the BATTERY VOLTAGES WILL BE DIFFERENT.i[lower with the fridge "ON"]

Despite the knowalls this is a more common problem than many realise
& is entirely due to not following well known principles & the FRIDGE makers recommendations

Chris it would help if you could indicate
[a] the Fridge model number as from that we can determine the actual fridge current draw
[b]Also the actual loacation of the Ctek distance [cable lenth & cable size /actual copper core dia from the Ctek to the battery
also the cable run length & copper di from the Vehicle battery to the Ctek
[c]Also What is the max charge voltage of the vehicle alternator

With that information I can give GOOD info on how to get the best possible fridge performance for both the fridge & the Ctek


PeterQ
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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 11:44

Monday, Sep 16, 2013 at 11:44
before you start again, yes the fridge shouldn't be run on the battery whilst it's being charged but that's the way it has been wired.

Interestingly from what I have read Ctek state that it is ok to have a load connected whilst the battery is being charged.

Cheers
Leigh



Yes ,It is ok to have a load connected while the battery is being charged!
It will not damage the Ctek
BUT if that load is sucking ALL of the Ctek output, it cannot charge the battery
IT IS AS SIMPLE AS THAT

IF it is an AES fridge it will have a high rated element ,depending on model 15+amps draw.

I do not see anywhere where Chris has said the problem exists with ALL input sources!!
AES will select 12V heater operation as 2nd option when 240V is not available & 12V is
If the fridge is wired as I believe it has 12V available from the house battery
GAS is the last option, when no other energy source is available


Stuffed up wiring is far from uncommon[ even by van makers]
The problem I have suggested has been found on many forums
The Sypthoms are typical of what one would expect with ALL the 12V terminals of the fridge commoned & connected to the house battery


PeterQ
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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 11:50

Monday, Sep 16, 2013 at 11:50
PeterQ

ozichris wrote above if you bother to read through


"The problem occurs when the fridge is running on gas or 240V"

Cheers

Leigh

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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 11:56

Monday, Sep 16, 2013 at 11:56
HI
Oooops, my apology I see Chris did post a follow up saying the problem occurs with both gas & 240V operation

BUt I still suggest Chris carry out those checks I suggested
The voltage checks could reveal were the problem exists
Doing so will indicate if load on the Ctek is the problem

Perhaps he has a malfunctioning fridge control module.

There is realy not much in the Dometic control module that could put out "interfernce" that would affect the Ctek control system, apart from the electronic ignition, but that should only be for a few seconds when switching to "gas" operation


PeterQ
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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 12:00

Monday, Sep 16, 2013 at 12:00
HI
One problem is Chris has not told us what type/ model Ctek he is referring to
Or have I missed THAT too??
Is it A DC to DC charger OR a MAINS charger???


PeterQ
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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 12:20

Monday, Sep 16, 2013 at 12:20
A fair question, someone above indicated that the setup Chris's unit has is a DCDC charger, Chris said he took it to an auto elect so that would alsp imply DCDC, but then again he indicated the problem is with gas or 240V, one would assume that if the fridge is running on gas or 240V you would be charging the battery with a 240V charger at that time.

So yes is a grey area that Chris can fill in if he hasn't sorted the problem already.

Cheers
Leigh

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Follow Up By: ozychris - Monday, Sep 16, 2013 at 12:38

Monday, Sep 16, 2013 at 12:38
Finally got to find the information
It is a C-Tek Multi XS 7000
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Follow Up By: Travis22 - Monday, Sep 16, 2013 at 15:16

Monday, Sep 16, 2013 at 15:16
Copied from an old thread regarding Cteks and Engel power packs.

From a member 'Bertus' on that forum;
"Ctek is a advanced computerised charger not a power supply it supply a signal rather than a voltage. Ctek uses power electronics and high frequencies that is why it is so small if compared to other chargers. The transformer in it is very small thanks to the high freqencies. It analize the battery and decide in what mode it will charge it. So it depends what it "sees" what it will do. A battery is a storage device. If you hook up your fridge there is a coil on the otherside which it does not under stand."

From Ctek SA;
As Bertus explained CTEK is a electronic device, called switch mode charger not a linear charger "battery cooker" Linear chargers has no intelligence and merely converts 220 to 12/24 volts, Switch mode on the other hand has a programmed micro chip to annilize the battery and then select various charging programs to suit the batter condition best. CTEK measures the resistance in the battery, thus determining the condition, then proceed with desulfitation, and different charging cycles to get the battery to 100% charge, then over to float and pulse mode. The problem with the Engel battery pack might be the same as what we had with charging of late model BMW motorcycles, they have built in protection to prevent the use of poor quility chargers, that might damage the electronics. CTEK got qualified and now an overriding source code is built into the charger and CTEK is branded by BMW. We are in contact with ENGEL in Australia to determine the problem, will soon have the answer, and solve your problem.

Personally i still think its some simple problem of interference.

Travis.
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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 16:29

Monday, Sep 16, 2013 at 16:29
HI Travis & others

May I suggest you CAREFULLY read the above post by Travis
& try to understand what is being said
You will find it is very much on the same lines that have posted

[Quote}"It analize the battery and decide in what mode it will charge it. So it depends what it "sees" what it will do.
[End Quote}


It analyses the battery & responds to it's believed SOC which is primarily determined by the BATTERY VOLTAGE @ that point
Just as I have indicated



quote"A battery is a storage device. If you hook up your fridge there is a coil load,[the fridge which it does not understandend[ quote]

THe load from what ever source gives a false SOC reading for the battery
The charger acts according to that false reading

Quote".CTEK measures the resistance in the battery, thus determining the condition, then proceed with desulfitation, and different charging cycles to get the battery to 100% charge, then over to float and pulse mode.[ end quote]

The Ctek does exactly the same as ALL modern multi stage chargers IT reacts to what it sees as opposition to current flow [resistance]
But with a battery that APPARENT resistance has TWO factors RESISTING CURRENT FLOW
[aCtek uses power electronics and high frequencies that is why it is so small if compared to other chargers. The transformer ] the actual battery internal resistance & more important & the most variable the ACTUAL OUTPUT VOLTAGE AT THE TIME OF ANALISING
In EVERY case THE voltagethat the charger SEES at its terminal decides the charge regime
ANY thing that leads to a FALSE SOC reading confuses the charger


THAT has /IS the whole point of ALL my posts on the subject

{Quote]
Ctek uses power electronics and high frequencies that is why it is so small if compared to other chargers.[end quote]
The same as all modern chargers & power converters
ie have no heavy iron cored transformer
The high speed switching Electronics are in the CHARGER
THERE ARE NO HIGH SPEED SWITCHING ELECTRONICS IN THE FRIDGE to cause interference

PeterQ
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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 16:41

Monday, Sep 16, 2013 at 16:41
HI Chris
Good that a start ,
now can you get those other details?
FRIDGE model?
cable Distance from charger to battery?
Cable size?

IS the fridge wiring connected direct to the battery?
Can you do those tests I suggested?
would strongly suggest to Chris, that he does some very simple tests:
[1]FIRST DISCHARGE THE HOUSE BATTERY TO SAY 12.5V ie so it requires charging
[2]with the fridge not switched on, but Ctek charging the house battery]
CHECK THE VOLTAGE AT THE HOUSE BATTERY
[3]Then immediately turn the fridge on to 12V operation & RECHECK the voltage AT the HOUSE battery

[4]Report your results here
I will predict that the BATTERY VOLTAGES WILL BE DIFFERENT.i[lower with the fridge "ON"]



PeterQ
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Follow Up By: oldtrack123 - Monday, Sep 16, 2013 at 16:53

Monday, Sep 16, 2013 at 16:53
HI Chris
It is a mains charger!
Do you have the manual for the Charger?
Are any error lights showing ?
Have you set it to the correct operation to charge your battery type?
It is only a 7A max charger
Those voltage tests above are important to determine your problem.
PeterQ



PeterQ
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Follow Up By: Member - LeighW - Monday, Sep 16, 2013 at 17:01

Monday, Sep 16, 2013 at 17:01
PeterQ,

Hate to disagree but all modern electronics these days including fridges will use micro processor chips to control the unit. It is quite common for these to cause RF interferences. It is also quite common for switched mode power supplies to do the same thing. I also suspect the fridge motors are probably brushless and run ac but I could be wrong so happy to stand corrected, if they do then this could be another source of interference.

Any power supply that is generating around 30Hkz in the convertor can cause interference.

Ctek themselves indicate it is ok to have a load connected to the charger whilst it is charging, yes it will upset the charger somewhat and obviously not desirable.

The chargers are not all that smart, they look at the terminal voltage of the battery and go from there, this is not the greatest method as the terminal voltage will change depending on the SOC of the battery, its temperature, how long it has been at rest and if a load is connected or not.

Again, Ctek have said it is ok to have a fridge such as a compress fridges connected and I know of a lot of people who have this sort of setup as well as other accessories connected whilst the battery is being charged with no problems.

Ctek have also indicated above that a particular power supply caused problems with the Ctek, this power supply most likely also incorporates a switched mode power supply which it appears interacts with the ctek to cause issues.

It would seem either Ctek should stop telling their customers that you can have a load connected whilst charging or fix the bugs with their unit.

Cheers
Leigh

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Follow Up By: Nomadic Navara - Tuesday, Sep 17, 2013 at 16:33

Tuesday, Sep 17, 2013 at 16:33
Firstly, why is the OP reluctant to advise the fridge model? I still assume it is an AES model.

Secondly, I think the RFI problem suggestion in a load of crap. Cteck chargers are fairly robust and well filtered. In the off chance it really is an RFI problem then the charger would most likely be faulty.

The OP stated " The problem occurs when the fridge is running on gas or 240V. The fridge requires a 12 V input at all times to run the control system. If I connect the fridge to a small 12V battery that I use for my fish finder the problem goes away and the charger charges the house battery as normal."

An AES fridge has two 12 V inputs. A light duty one that should be connected to the house battery to power the logic board. The other, a heavy duty high current one, should be run to the alternator/starter battery in the tug and no where else. If the fridge is wired this way, when you have mains supplied to the van to power the C-Tek Multi XS 7000 the fridge should run on 240 V power by default. It should not matter what charger you apply to the house battery the fridge should remain powered from 240 V power. If as the OP says starting the charger up also starts the 12 V power operation, this indicates to me there is a wiring problem.

When the OP says "If I connect the fridge to a small 12V battery" which of the two 12 V inputs is he connection to this additional battery? Is it the light duty one, the heavy duty one or both? If the heavy duty one is normally connected to the house battery then there is no problem with the logic board. The logic board is doing its job correctly. It is working normally. That connection is probably the one that is used to trigger the 12 V fridge operation. What is happening is that when the battery charger is switched on, the logic board sees a rise in voltage and thinks it should switch the fridge to 12 V operation. When the fridge is wired to the external battery the logic circuitry does not see this rise in voltage and stays on gas.

The lack of battery charge when this faulty condition is due to the battery charger only able to supply half the current required by the 12 V element, the rest would be supplied by the house battery.

Correcting the wiring of the fridge will cure the problem. Make sure there is no interconnection between the house battery and the 12 V fridge element. If you want to charge the battery from the tug then install a separate cable from the tug.

To those who suggested PeterQ and I should read the OP's posts correctly I suggest the boot is on the wrong foot.
PeterD
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Follow Up By: Member - LeighW - Tuesday, Sep 17, 2013 at 19:35

Tuesday, Sep 17, 2013 at 19:35
PeterD

Interestingly OP has never actually stated the charger didn't charge when the fridge was running on 12V. Everyone just seems to have jumped to that conclusion.

He did write as you pointed out:

The problem occurs when the fridge is running on gas or 240V. The fridge requires a 12 V input at all times to run the control system. If I connect the fridge to a small 12V battery that I use for my fish finder the problem goes away and the charger charges the house battery as normal."

This could also imply the charger did not work when Gas or 240V was manually selected, before he resorted to using the battery. Assuming you can do this, if fridge is wired incorrectly which it probably is, why didn't the charger fire up when the fridge is running on gas or 240V
without the addition of the extra battery?

One could assume the OP indicating the charger is not charging means exactly that the charger is not charging, not can't supply the load. As he has enough brains to understand and power supply is required and where to connect it to one would assume he can tell if a charger is charging or not.

You wrote:
"An AES fridge has two 12 V inputs. A light duty one that should be connected to the house battery to power the logic board. The other, a heavy duty high current one, should be run to the alternator/starter battery in the tug and no where else.

If the fridge is wired this way, when you have mains supplied to the van to power the C-Tek Multi XS 7000 the fridge should run on 240 V power by default."

Note: as the heavy is connected to the tug it can't be used to sense the charge voltage being detected in the van as you state later.

"It should not matter what charger you apply to the house battery the fridge should remain powered from 240 V power. If as the OP says starting the charger up also starts the 12 V power operation, this indicates to me there is a wiring problem."

Where did OP state the above?

"When the OP says "If I connect the fridge to a small 12V battery" which of the two 12 V inputs is he connection to this additional battery? Is it the light duty one, the heavy duty one or both? If the heavy duty one is normally connected to the house battery then there is no problem with the logic board. The logic board is doing its job correctly. It is working normally. That connection is probably the one that is used to trigger the 12 V fridge operation."

You have contradicted yourself above, if the heavy goes to the tug it can't be used for charge sensing.

"What is happening is that when the battery charger is switched on, the logic board sees a rise in voltage and thinks it should switch the fridge to 12 V operation. When the fridge is wired to the external battery the logic circuitry does not see this rise in voltage and stays on gas."

The above doesn't make sense, according to this theory if you didn't have a charger in your van the fridge would never switch to 240V!

Form a self proclaimed expert your deductions leave a bit to be desired:)

Still a few answered questions but as the OP will probably never return we will never know.

Cheers
Leigh

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Follow Up By: oldtrack123 - Tuesday, Sep 17, 2013 at 19:58

Tuesday, Sep 17, 2013 at 19:58
Hi Leigh
After reading your last post it seems you have a problem
You seem to be confusing COMPRESSOR FRIDGES with a 3way ABSORPTION FRIDGE!!
The 3ways do not require a switch mode converter or any other high freq equipment of any sort,why would they need one
The only component they that does a conversion is the automatic ignition^THAT is only for a few seconds when switching to GAS
The so called electronic contol unit's basic job is determine what sources of energy are available ,& search for them in this sequence

First 240V
if no 240V then 12V
If neither of the above GAS's

iAS PeterD has also pointed out
If the fridge has ALL 12V inputs wired to the house battery
[& THAT is a common error made by many van makers]
then a 7A charger will not meeet what could be 16A load JUST FOR THE FRIDGE.
It certainly will not have the capacity to CHARGE the battery at the same time AND the fridge could be actually pulling power from the batter

The output voltage of the battery will drop[the OP has not even told us the size of that battery ,& it may be very sick [lost a lot of it's claimed capacity EVEN THOUGH IT FULLY CHARGES by voltage reading]
Before anymore is done HE SHOULD CARRY OUT THE TESTS I HAVE SUGGESTED
HE SHOULD ALSO CONFIRM:
FRidge model number
Battery Amphrs capacity
Distance from charger to battery[length of cable]
cable size used
That the Fridge & the Charger are both connected DIRECTLY to the battery terminals

If he can get acees to the fridge rear terminal he could check that the two terminal bolcks for 12V have not just got ONE neg & ONE pos lead feeding both.!!
Because that is how many so called experts have wired them!!
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Follow Up By: oldtrack123 - Tuesday, Sep 17, 2013 at 20:06

Tuesday, Sep 17, 2013 at 20:06
HI
By the way I know exactly how, modern switch mode converters, battery chargers & lots of other electronics work
On top of that I do know how absorption friges work including those with an AES system,& the difference between them & Danfoss compressor units/motors, Engel fridges,


PeterQ
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Follow Up By: oldtrack123 - Tuesday, Sep 17, 2013 at 20:12

Tuesday, Sep 17, 2013 at 20:12
Hi leigh
I suggest you reread his OP
He did not say the charger did not work
He said it does not charge the battery
WHICH IT CANNOT IF ALL IT"S OUTPUT plus some from the battery is being dragged by the fridge

PeterQ
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Follow Up By: Member - LeighW - Tuesday, Sep 17, 2013 at 20:23

Tuesday, Sep 17, 2013 at 20:23
Hi PeterQ,

No I'm not getting confused just was trying to point out that even an old absorption fridge will be micro processor controlled these days, much easier to write firmware and have a few digital circuits than build analogue. Any equipment running micro processors can generate Rf noise if not well designed and everyone builds to a price.

Others seem to have a higher opinion of Ctek products than myself, have seem much better commercial units but then you get what you pay for.

PeterD has stated that he doubts that interference could be a problem and he's probably correct, but having spent more years working in electronics try to solve incompatibility issue between different brands of equipment I would never discount anything off hand.

Ctek in the correspondence above acknowledge some compatibility issue with there products, be it Rf or induced.

But as you say only hard data provided by the OP will solve the puzzle and it is much more likely to be wiring in this case.

Cheers
Leigh

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Follow Up By: Member - LeighW - Tuesday, Sep 17, 2013 at 20:58

Tuesday, Sep 17, 2013 at 20:58
PeterQ

"Hi leigh
I suggest you reread his OP
He did not say the charger did not work
He said it does not charge the battery
WHICH IT CANNOT IF ALL IT"S OUTPUT plus some from the battery is being dragged by the fridge"


Agree with the above, but won't charge could also mean the Ctek won't start its charging program caused by for example by the battery voltage being to low, I'm giving the Ctek the benefit of the doubt and assuming it has a diagnostic program and gives the battery a pre-charge health check.

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Leigh

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Follow Up By: Member - LeighW - Tuesday, Sep 17, 2013 at 22:33

Tuesday, Sep 17, 2013 at 22:33
Some research finds at least on the model I looked at:

The fridge monitors the 240V to see if it is available.

The fridge monitors the 12V to see if it is available.

Assuming auto operation, the fridge selects:

240V first by default, then 12V then gas.

Again I pose.

OP stated charger will not charge, if 240V is available to run charger then one would assume it is available to the fridge.

If 240V is available fridge switches to and runs of 240V.

Under this condition the only power being drawn from the 12V side is the power required to run the fridges control panel and not the heater. One could fairly assume that this is not going to be very large ie a couple of amps.

As the fridges 12V heater is not running and the fridge is only drawing a couple of amps or so I again pose my question, why didn't the Ctek fire up and charge the battery even if both supplies are wired to the house battery?

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Leigh

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Follow Up By: Member - LeighW - Tuesday, Sep 17, 2013 at 22:47

Tuesday, Sep 17, 2013 at 22:47
If your suggesting the small load from the control circuit is pulling the house battery down to the point where the Ctek thinks the battery is faulty won't charge it, would there still be enough voltage for the fridge to operate at this level?

What's the lowest voltage a Ctek will accept? I can plug my smart chargers into the camper without a battery connected and the charger will act as a power supply as long as it has a load on it. I would have thought Ctek would be similar?

Cheers
LeighW

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Leigh

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Follow Up By: oldtrack123 - Wednesday, Sep 18, 2013 at 13:17

Wednesday, Sep 18, 2013 at 13:17
Hi Leigh
Obviously you have not had much experience with Dometic ABSORPTION fridges
About the only ones that have ANY FORM of "electronics" are the AES models
And with those it is simply for
[a]" AutomaticEnergy Source "selection in the steps posted earlier

[[b] voltage monitoring of the 12V heater supply to:
[i]Know when the ALTERNATOR is outputting sufficient voltage to indicate that the fridge will not discharge the crank batteryi
[2]to disconnect the fridge IF the battery voltage falls due to lack of sufficient alternator output

when on gas :
[3] Automatic ignition until the flame is established,
now that does require some high speed switching to generate the high voltage required
BUT THAT ONLY HAPPENS for a short period when first switching to gas.
The gas safety is valve is a simple therocouple supplied device

There May be some very short term switching transients when initially selecting the source, which is based purely on voltages available in the steps oulined.
A Ctek charger would have to cope with far more than that in every day use


ALL other models are simply straight Switch or Switch & RELAY controlled
PeterQ
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Reply By: oldtrack123 - Tuesday, Sep 17, 2013 at 23:31

Tuesday, Sep 17, 2013 at 23:31
Hi Leigh
Yes he does say it happens on gas & 240v & no mention of 12V

We are all wasting our time simply because we do not know::

[a]What Model fridge the OP has ,it may not be an AES model but the manual selet equivalent
It may even be the model that only has ONE element for both 12V & 240V operation!

[b]
Exacty how the fridge is wired

Yes he does say it happens on gas & 240v & no mention of 12V

c]
IS the charger actualy putting out a charge or switching off[your interference theory] HE has not said that
He has said, it is not charging the battery

But if the wiring is stuffed upthe fridge t may also be running on 12V
It all depends on one of the details that have not been supplied , .MODEL #
Then if the two 12V inputs terminal on the fridge have been commoned
AND THAT IS NOT UNCOMMON by those who do not have the brains to think why are there TWO sets of 12V terminal blocks

The easiest way for him to find that is to test the battery voltages AS I HAVE suggested

THAT WILL SHOW IF A HEAVY LOAD IS BEING APLLIED.
IT IS AS SIMPLE AS THAT

Then we can all forget about complicated theories that are not based on known facts


PeterQ
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Reply By: ozychris - Wednesday, Sep 18, 2013 at 15:02

Wednesday, Sep 18, 2013 at 15:02
Thanks all for the interesting ideas.
I think Leigh seems to understand the problem with his reply on Sunday, Sep 15, 2013.
The fridge is fine(not sure of the model number but it is an automatic 3 way. dometic). The batteries are fine. the C-Tek is fine. The connection, and everything else is fine. As I said it is only the trickle required in the fridge controller.
I haven't been able to get to Jaycar yet but will talk to them and probably get a ferrite trap as Leigh suggested.
Thanks again
Chris
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Follow Up By: oldtrack123 - Wednesday, Sep 18, 2013 at 19:51

Wednesday, Sep 18, 2013 at 19:51
HI Chris

Well ,now I am not sure what your OP was all about IF every thing is fine

I hope You will come back & TELL us ALLl, if the Ferrite suppressors cure your "problem "??
Or has it already disappeared??
. What ever it was!!!!

PeterQ
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Follow Up By: ozychris - Wednesday, Sep 18, 2013 at 21:53

Wednesday, Sep 18, 2013 at 21:53
No the problem has not disappeared.. I think only Leigh seemed to understand what it is. What I was trying to say in my last post is that the problem has nothing to do with most of the things we were told might fix it.
If we find the solution put up by Leigh is helpful I will let you know. Otherwise we will just have to continue with our small battery running the controller on the fridge while we charge the other battery.
Regards
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Follow Up By: oldtrack123 - Wednesday, Sep 18, 2013 at 22:03

Wednesday, Sep 18, 2013 at 22:03
Hi
So Can we assume from that THAT you have actually done some tests??
You do seem reluctant to actualy to answer some of those questions asked of you .which would assist in determining what is wrong.

Can we assume you have checked at the back of the fridge & checked that FIVE Cables [3 small & TWO heavy are connected to the correct terminals of the fridge

Or is it just that Leigh's answer suits you best??'


PeterQ
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Follow Up By: Member - LeighW - Wednesday, Sep 18, 2013 at 22:04

Wednesday, Sep 18, 2013 at 22:04
Chris,

If you still have problems contact me at hkbelect@hotmail.com and we can discuss further.

Cheers
Leigh

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Follow Up By: Member - LeighW - Wednesday, Sep 18, 2013 at 22:12

Wednesday, Sep 18, 2013 at 22:12
PeterQ,

Your not going to help Chris by brow betting him, obviously at this time he doesn't wish to answer your list of demands.

We may all need them eventually to come up with a solution but until he decides to supply the info why don't you just sit on the side instead of brow beating him?

Leigh

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Follow Up By: Member - LeighW - Thursday, Sep 19, 2013 at 09:04

Thursday, Sep 19, 2013 at 09:04
Chris,

After digesting all the above and making the following assumptions:

*You have an auto energy selecting fridge and it is able to select 240V.
*That 240V is available to the fridge.
*The charger won't start charging, ie the charger is not indicating it is charging.
*The van is not connected to a car.
*When you connect the little battery you are connecting it to the control circuit circuit of the fridge.
*Assuming the wire is as you say correct.

If all the above is correct then the most likely scenario is that the van battery has been discharged to a point whereby the Ctek charger sees the battery as fault or not connected.

By disconnecting the fridge your probably allowing the terminal battery voltage to recover to a point where the Ctek sees the battery and starts charging.

If the above turns out to be true your options are:
*Don't let the battery get this low as it will be damaging the battery.
*If it should, and the car can charge the battery then connect van to car and charge for awhile then try the Ctek again.
Throw away the Ctek and get a charger that will charge a deeply depleted battery.

If the above doesn't turn out to be the case then you will either need to start making some voltage measurements and post as suggested and provide model numbers etc.

Cheers
Leigh





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Reply By: Member - LeighW - Thursday, Sep 19, 2013 at 09:30

Thursday, Sep 19, 2013 at 09:30
PeterQ

In Chris case if the two power sources are connected together as long as there is some charge in the battery the fault would be evident only if the house battery is being charged and 240V is not available to the fridge.

As you have indicated, the fridge defaults to 240V, assuming when the charger is on the fridge also has 240V the fridge will switch to that and never attempt to run of 12V using the house battery.

If 240V is not available to the fridge then yes it will probably see this as the alternator charging and switch to it, I would then imagine the load would cause the voltage to drop the fridge will then try gas and go into a cyclic operating mode from there.

I'd also still bet that the AES uses a micro to control all the functions.

Cheers
Leigh

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Follow Up By: oldtrack123 - Thursday, Sep 19, 2013 at 20:01

Thursday, Sep 19, 2013 at 20:01
Hi Leigh
I do not know if you noted my reference to some 3WAY Dometic models only having a single element[240V]
Now if Chris has THAT model [Sad that we do not know],You could be quite correct with interference.
They use an inbuilt crude square wave inverter when on 12v.!!

But,as I said ALL supposition due to lack of necessary information.

I do not think Chris has acutally answered the key question :
What does he mean by "not charge the battery" ??
or put another way does the Ctek completely switch off" ?
Or does it stay on but "not charge the battery"???

If it completly swiches "'OFF", does it stay "OFF" or restart after a few secnds or minutes?

I am sure YOU would agree rermote fault finding finding is much easier& problems /faults more easily determined If the person at the other end cooperates with details as requested
Without those details we are ALL just stabbing in the dark

PeterQ
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