caravan battery problem

Submitted: Friday, Jun 12, 2009 at 10:14
ThreadID: 69744 Views:3415 Replies:10 FollowUps:7
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We have an anderson plug connected from car to caravan but sometimes after travelling for a while we find that the battery in the van is dead flat. We had the connections and battery checked and we're told they we're ok.
After travelling for 2hrs yesterday we found that the battery in the van was dead flat, hence no lights, I had to connect the anderson plug and charge from the car which straight away started the battery charger operating in the van which was hooked up to 240v, after about 1/2 an hr I could turn off the car.
We also have an inverter hookked into the system. Can anyone shed some light on the problem, excuse the pun!!

Cheers Roy
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Reply By: DIO - Friday, Jun 12, 2009 at 10:21

Friday, Jun 12, 2009 at 10:21
Anderson plug not connecting properly, wire(s) from battery to Anderson Plug too small (voltage drop), possibly break (poor connection) from battery to Anderson Plug. Suggest you consult an auto electrician if you don't feel you are compotent enough to resolve yourself.
AnswerID: 369643

Follow Up By: Roy and Pam - Friday, Jun 12, 2009 at 14:02

Friday, Jun 12, 2009 at 14:02
Hi, I have had all of that checked by an Auto elect he said everything was fine?????
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FollowupID: 637069

Reply By: Peter McG (Member, Melbourne) - Friday, Jun 12, 2009 at 10:34

Friday, Jun 12, 2009 at 10:34
Roy

What are you towing with? You may not be getting a good voltage level to the van. You could look at fitting a Ranox 12v charger to the van. This would ensure that the van is getting the right voltage but certainly need to check connections and also check that you don't have too much drawing form the battery while towing. Is the fridge 12v/gas? If so then you will have a fair draw from the fridge when towing.

Cheers

Peter
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AnswerID: 369645

Reply By: Member - Rodney B- Friday, Jun 12, 2009 at 10:36

Friday, Jun 12, 2009 at 10:36
Roy
Not enough information to diagnose this problem.
When you have the anderson plug in and the car running what is the voltage at the caravan battery. Are your caravan battery terminals clean and tight and what was running in the caravan for that 2 hours to flatten the battery.
Cheers
AnswerID: 369646

Follow Up By: Roy and Pam - Friday, Jun 12, 2009 at 13:58

Friday, Jun 12, 2009 at 13:58
Hi Rod

I'm not sure what the voltage is when plugged in but I had the plugs checked buy an auto elect the other day he said there was 14.5v at the car end and van end of the anderson plug and the battery was also showing 14.5v
I have checked the terminals they seem fine, the only thing that was running at the time was the fridge, could the inverter have anything to do with it as it is connected at all time?
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FollowupID: 637068

Follow Up By: oldtrack123 - Friday, Jun 12, 2009 at 20:21

Friday, Jun 12, 2009 at 20:21
Hi
I would suggest you get the auto lecy to check for voltage drop due to undersized cables under full load.
If he does not under stand that get one who does.
This test must be done with fridge running hooked up to tug &
engine running.
You WILL get a differrant reading,lower @ the van battery & the fridge terminals than @ the car battery.
It is the size of the differrance that is critical. I will take a guess & say you will probaly find your voltage under load @ the fridge is around 11v .noooo good. THe fridge will be loading the undersized cables to such an extent that the battery is not getting any charge & the fridge will be drawing part of its power from the van battery
The van battery could also be no good, capacity wise, battery can still charge to 14+ v & have very little capacity
If it is a flooded wet cell check it with a hydometer.
If the cables including the ones in the car are seriously undersized even a Ranox may not solve your problem.
Also do not rely on frame return for neg line , should have full sized cable back to car battery
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FollowupID: 637137

Reply By: Ray - Friday, Jun 12, 2009 at 10:53

Friday, Jun 12, 2009 at 10:53
Hi. just a thought? Is the inverter connected all the time? You may be trying to charge the battery through the inverter from the same battery.
AnswerID: 369650

Follow Up By: Roy and Pam - Friday, Jun 12, 2009 at 13:51

Friday, Jun 12, 2009 at 13:51
Hi Ray, Yes the inverter is connected at all time, do you think that could be the problem? if so when should I be useing the inverter?
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FollowupID: 637067

Reply By: Moose - Friday, Jun 12, 2009 at 13:15

Friday, Jun 12, 2009 at 13:15
Battery must be buggered if you started off with it fully charged and it was flat after only 2 hours. Unless you're running something that sucks heaps more out than goes in - unlikely.
How was battery checked? Under load or just with multi meter?
AnswerID: 369659

Reply By: tim_c - Friday, Jun 12, 2009 at 13:58

Friday, Jun 12, 2009 at 13:58
Roy, very simply: a battery will become "flat" only if you are drawing more from it than you are putting into it (or if it's stuffed). Therefore, assuming a healthy battery: if the battery is flat, it's either not being charged, or something is connected that is using more power than the charging circuit can provide.

There could be a number of things contributing to this:
* A poor charging circuit in the car (ie. something not working properly)
* An alternator that may not have sufficient capacity for the task
* Other power requirements in the car including charging of any auxiliary batteries in the car, fridge, headlights and driving lights, etc.
* Power requirements in the caravan (as someone mentioned: possibly a 3-way fridge running on 12v, and what you might have plugged into the invertor)
* Insufficient wiring from the car charging circuit to the caravan battery/ies - the Anderson plug is just one link in the chain: to run from the vehicle alternator to the caravan battery probably requires more than 10-15m of wire - is this adequately rated/sized to reduce voltage drops and allow sufficient current flow? Is there a good earth connection as well?

Of course, all this assumes the caravan battery was charged before you left home! ...Or has the caravan been sitting idle in the backyard for the last ?? months, and then you hooked up the car and expected the caravan battery to be fully charged after a short drive?
AnswerID: 369662

Follow Up By: Roy and Pam - Friday, Jun 12, 2009 at 14:13

Friday, Jun 12, 2009 at 14:13
Hi Tim

The battery was fully charged when we left, I had the battery and connections checked by an auto elect he said everything was fine, there was about 14.5 volts at the battery and also the anderson plug at the car and van. I did have the parking lights on while driving and the only thing running in the van is the 3 way fridge switched over to 12v. I do have an inverter connected at all time could that have anything to do with the problem? if so when should the inverter be used??? By the way the car is a Ford falcon.

Cheers
Roy
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FollowupID: 637070

Follow Up By: tim_c - Friday, Jun 12, 2009 at 15:14

Friday, Jun 12, 2009 at 15:14
Hi Roy,

Parking lights won't make much difference (both to power usage and to your visibility on the road!)

3-way fridges do use quite a bit of power on 12v so it will use up your caravan battery quite quickly if it's not getting a decent top-up from the car.

It seems to me that the fridge is using more power from the caravan battery than the alternator is putting back in. Yes, you said the connections were all checked by auto-elec and were fine - did he check for the rating/size of the wires etc. as well? It is possible to have a good connection but have wires that are too small. If the wires are too small, you will still get some charge to the battery but not enough to keep up with the power used by the fridge. The issue is more critical having such a long run of wire (ie. from the alternator at the front of the car all the way back to the battery in the caravan). When the Anderson plug was connected, were new wires (ie. thick cored with lots of copper) run all the way driectly from the car battery?

Do you know what the car alternator is rated at? It may only be sufficient for the car in standard form - ie. Ford possibly didn't design it to run a fridge as well as all the standard equipment in the car so it's possible you might need to upgrade the alternator - yes, more $$$!

Your auto-electrician should be able to test the alternator and see if it's keeping up, check the health of your batteries (car and caravan), assess the power required to run your fridge etc. and check the wires etc. are adequately sized for the job, etc.

Finally, if nothing was plugged into the invertor, switch it off or disconnect it. They usually do use a little bit of power even if nothing is plugged into them (eg. to run a cooling fan, etc.). It's not usually much, but it is unnecessary if you're not using it at the time.

Hope this helps - let us all know how you get on.

Cheers,
Tim.
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FollowupID: 637079

Follow Up By: Geoff (Newcastle, NSW) - Friday, Jun 12, 2009 at 16:13

Friday, Jun 12, 2009 at 16:13
Hi Roy,
I'm with Tim on this.

I'd put money on the wiring being way too small for the job at hand.

It'll all look fine with the engine running, caravan hooked up and everything in the caravan turned off.

As soon as you spark up the fridge on 12 volt I guarantee the voltage at the caravan battery will begin to fall. It'll continue to fall until the battery is dead flat regardless of whether the engine is running and the alternator is outputting power.

How thick exactly is the wiring between the alternator and the caravan battery and how long is it exactly?

Geoff

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FollowupID: 637088

Reply By: Craigjackaroo - Friday, Jun 12, 2009 at 18:22

Friday, Jun 12, 2009 at 18:22
What kind of circuit protection is being used between the van and the car.?

Ideally there should be a fuse or breaker on both the car and the van as power can flow from either power source if there is a fault.
I have heard of auto reclosing circuit breakers, like used on electric brakes failing and causing high resistance faults. Under no load the voltage at the plug will read fine. It is not until you use a decent load like a driving light or something that you will see a significant voltage drop.
Another suggestion is to use a Jaycar circuit breaker with voltage and current reading on the van or car to check voltage and current flow.
AnswerID: 369704

Reply By: steved58 - Friday, Jun 12, 2009 at 21:52

Friday, Jun 12, 2009 at 21:52
Not being an expert I can't help technically however you said yourself it went flat while driving the car Then ran the car for half an hour while on 240volt so was the 240volt charging the battery or the car also was the fridge on 240volt

Try
1 - Run the car when battery is flat with fridge off no 240 volt is it charged now

2- Run the van on 240volt when the battery is flat fridge both on and off is it charged now

It may be charging from the 240volt Im with the rest and think the wiring is too small it may be a pain to run the battery down and run through a logical sequence but may be the only way

Steve

Ps make sure not to run the battery to far down check with a meter otherwise damage to the battery could occur
AnswerID: 369747

Reply By: mr fixit - Saturday, Jun 13, 2009 at 09:08

Saturday, Jun 13, 2009 at 09:08
>After travelling for 2hrs yesterday we found that the battery in the van was >dead flat, hence no lights, I had to connect the anderson plug and charge >from the car which straight away started the battery charger operating in >the van which was hooked up to 240v, after about 1/2 an hr I could turn off >the car.
>We also have an inverter hookked into the system. Can anyone shed some >light on the problem, excuse the pun!!

its this bit that confuses me
>straight away started the battery charger operating in the van which was >hooked up to 240v

Was the charger hooked up to the inverter ?

Doug
AnswerID: 369768

Reply By: wafarmer - Saturday, Jun 13, 2009 at 13:29

Saturday, Jun 13, 2009 at 13:29
Hi

I had something similar done to me on a new camper by the "experts" they hard wired the battery charger to the inverter so the battery charger was charging the battery which was powering the inverter which was powering....................... um I shouldn't have to describe the result of this aye.

Also had the Truma Gas / Electric hot water system running off the inverter and when told it tripped out the inverter I was told it was my fault I had insissted on too smaller inverter, I ask what about the batteries???? he hung up the phone.

I would say it is another case of the attempted invention of perpetual power.

cheers

wafarmer
AnswerID: 369799

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