Problem Charging Deep Cycle Batteries from Alternator

Ta Col - That is why I connected the 80w Solar - or so I thought - Cheers

Star Bug - The fridge was mentioned - Waeco CF80

I assumed they were fully charged as I had not long topped them up and had not used them

I thought faulty battery, but I am told they are OK - Might get someone else to put a load test on them

Fridge was working hard freezing freshly caught bait :-)

I was expecting a couple of days :-)

Cheers

Drivesafe - I only assumed they were fully charged - I had topped them up for the trip during the week - I had not used them.

My cable is of ample size - When tested the full charge reaches the batteries - both positive and negative cables run front to tray.

I had them tested but as they were down on charge it might have not shown up a problem?

Thanks for that & Cheers

98TAJ - I tested with a Multi Meter when I saw the fridge fault light and the freezer not working.

12.9 volt at both batteries car switched off.
13.9 when running the car and isolator had just opened

11.2 v at the fridge with fridge on (did not test with it off at the time)
13.9 at fridge when tested with the motor running (I do get higher readings at times)

Length of cables from fridge to the Batteries would be less than 1m (It is the original supplied cable though. Length of cable from Redarc to Batteries would be 2m.

Thanks for the reply

Tony,

the "11.2v at the fridge with fridge on" sounds far too low to me
I believe my fridge draws much more current than a 80 Ltr Waeco and will run with my 200ah battery system showing O.5v loss (12.2v - 12.3v) with no charge going into battery.
( just a quick thought; was it 12.2v and not 11.2v ? )

The low 11.2v indicates a battery is not holding charge, or the voltage measurement was taken when the fridge had been running for a hell of a long time and had partiality drained the battery, which is just a 'normal' characteristic anyway.

"13.9 at fridge when tested with the motor running " This is about 'normal' voltage in these conditions.

Maîneÿ . . .

Mainey - Defenitly 11.2v - Back at home this week so I will test each BATTERY UNDER LOAD BY ITSELF to see if I can Isolate the problem.

This is what it read after I saw the fridge flashing low voltage warning first thing in the morning.

Hope your Cape Run went well - Cheers (Hope it was you that went :-)

Tonyfish,
One other quick thing you can try is to run a second lot of wire in parallel with the original connection while the batteries are in the fault condition, or make up a short lead and bring the fridge closer to the batteries as a test. This will definitely determine if it is a voltage drop problem or Batteries. Just thinking about cost of batteries Vs cost of some bigger wire.
Tony fish you didn't happen to measure the voltage readings at the fridge with the light flashing and fridge OFF at all? If readings go back up Batteries should be fine and it will be a wiring problem.
Regards
Terry

Thanks Terry & Mainey

Did an Hour run with each battery connected independent.

Smart Charger on & wired to both batteries - Both Batteries 13.63v

Turn Charger Off Both Batteries independent Showed 13.02v - After test both are sitting at 12.3v independent - Reads same at Rectifier outlet

Battery 1 - Longest lead to fridge - Turn fridge on wait 5 min

Tested 11.85 at battery - 11.75 Battery-Solar Control at control - 11.55 Solar Controller-Waeco rectifier at rectifier and 11.00 coming out of Rectifier.

1 hr later - the same - Turn off - Battery back up to 12.3v & same at rectifier outlet

Battery 2 Closer to the fridge - Turn fridge on wait 5 min

Tested 12.05v at Battery - 11.98 Battery-Solar Control at control - 11.86 Solar Controller-Waeco rectifier at rectifier and 11.44 coming out of Rectifier.

1 hr later - the same - Turn off - Battery back up to 12.3v & same at rectifier outlet.

So appears wires are an issue and maybe battery 1 may be a bit suspect - They were both showing full charge (Float) on the smart charger.

Is that the way you would read the problem?

Cheers Tony

Tony,
I'm trying to interpret how this is wired up.
Do you run the fridge outlet direct from the battery or do you have the solar controllers and rectifiers between the battery and the fridge outlet?
If this is the case some of this gear will have diodes etc in the electronics which have their own voltage drops such as 0.6V for diodes in a rectifier. What is the size of the wire and what is the length of the run? Bigger is better when it comes to wire size and voltage drop with higher currents.
Regards
Terry

Thanks Terry - I see your problem :-)

1st battery to 2nd battery is about 500mm of 6mm - Anderson plug connected, so I can remove the camper with 1 Battery.
I have 6mm wire from the 2nd battery mounted on the camper to the Solar Control - about 500 mm
From the Solar Control Aux I run 6mm to the Rectifier - about 200mm
Rectifier to fridge about 500mm also 6mm

It appears it does lose the v between these

Might wire rectifier straight to battery & go bigger again with wire

I just used the above method to keep it short and clean without a lot of huge wires :-)

Tony,
See how that goes as it does seem to be a lot of joins and equipment between the battery and the fridge connection.
Regards
Terry

No way on earth will 2x 115ah batts run a Waeco 80 for 3-4 days without shortening battery life , 7years of running an 80lt Waeco tells me that using as designed freezer -15/18c fridge section is at +2/4c and dairy at +7c the unit will draw on average 64 amp hrs per 24 hrs ,
Fault indicator light flashes ,
1=low volts
2=fan overload
3=motor failed to start
4=low motor voltage
5= blocked vent.
The 80lt Waeco uses the Danfoss BD50 motor , which is designed to actually run on 24volts for best performance , Don't believe me ? Read the specs and instructions on the Unit and on the Mobitronics step down transformer sold to convert 240v for the 80lt waeco ,, 24v output , the fridge is happy to run on 12v but anything LESS reverts to failure.

Alloy

Keep your shirt on! I run a 39 litre Waeco which has a smaller compressor. That compressor too is native 24V with a switchmode adapter to run from 12V. (Creates a lot of electrical noise in the process too.) I would expect that the bigger Waeco is also native 24V with an inbuilt adapter for 12V. Believe you? Why not? Of course I believe you.

Our fridge takes around 25-30 Ah per day, giving about 2-3 days using about 2/3 of the 120 Ah battery capacity, which is as far I take it down in order to avoid shortening battery life. With the larger fridge coupled with twice the battery capacity I'd expect to get 3-4 days. The original post referred to a weekend, so returning to the original issue - With that size and capacity (even with your 64 Ah per day) he shouldn't have problems.


John

John - I am charging the batteries to do a full test of the circuit. Wire cable sizes and lengths I feel are not the issue. It was low voltage warning - when I ran the car and the Redarc switched over - problem gone, when the sun came up and the solar cut in, problem gone.

I would only expect 2 days at the most from these 2 batteries, but I would expect 2 days not 3/4 :-)

I think I need someone else to test the batteries, not sure my mechanic did a good job.

Thanks & Cheers Tony

Tony,

Sounds pretty conclusive. A low voltage problem when relying on the batteries, goes away with either panels or alternator pushing the voltage up. I'd suggest that a cheap digital voltmeter (Jaycar, Dick Smith etc) might provide useful answers. The fridge will draw maximum power when starting the compressor, which would be the best time to make some voltage measurements. I'd separate the 2 batteries temporarily charge them both fully and see if the problem relates to only one of them. If it does, you've found it, otherwise I'd first measure the voltage between the battery terminals and then work from there towards the fridge. With a well charged battery you should see over 12V all the way to the fridge. (The fridge must be running to get useful information from this test.)

HTH

John

Ta John - I have a multi Meter - Will run the fridge on each battery separately and take some readings

Cheers Tony

John Thanks for the advice - Did some more tests

Did an Hour run with each battery connected independent.

Smart Charger on & wired to both batteries - Both Batteries 13.63v

Turn Charger Off Both Batteries independent Showed 13.02v - After test both are sitting at 12.3v independent - Reads same at Rectifier outlet

Battery 1 - Longest lead to fridge - Turn fridge on wait 5 min

Tested 11.85 at battery - 11.75 Battery-Solar Control at control - 11.55 Solar Controller-Waeco rectifier at rectifier and 11.00 coming out of Rectifier.

1 hr later - the same - Turn off - Battery back up to 12.3v & same at rectifier outlet

Battery 2 Closer to the fridge - Turn fridge on wait 5 min

Tested 12.05v at Battery - 11.98 Battery-Solar Control at control - 11.86 Solar Controller-Waeco rectifier at rectifier and 11.44 coming out of Rectifier.

1 hr later - the same - Turn off - Battery back up to 12.3v & same at rectifier outlet.

So appears wires are an issue and maybe battery 1 may be a bit suspect - They were both showing full charge (Float) on the smart charger.

Is that the way you would read the problem?


Regards Tony

Tony,

You are losing too much voltage. The fundamental internal voltage of the battery is about 12.6V. Your tests are good, and summarising your results looks like this:


Image Could Not Be Found

Battery 1 is either not as well charged as Battery 2, or is sickening. (I suspect Battery 1 may be little more than a passenger, with Battery 2 doing most of the work.) Cable losses are pretty small and I wouldn't be concerned about them. The loss through the solar controller is also reasonably small. You are losing about half a volt going through the Waeco rectifier unit though, which is a worry.

The rectifier - One option would be to disconnect the Waeco rectifier and rearrange the wiring so that the fridge could be plugged into either the rectifier or the battery system. (Or instal a switch to make this selection.) This would result in the need for a manual operation to change from battery to rectifier which might be a nuisance. (It would be possible to retain automatic changeover and minimise voltage loss by using an external relay driven by the rectifier. This is not straightforward and would require some care and a bit of thought to implement safely. The Waeco power supply delivers 24V, and the battery/solar system 12V - it would be important to ensure that the two voltages never got connected together. Send me a member message if you'd like to discuss this option further.)

The solar controller. I assume that you are using the controller to feed 12V to the fridge and other loads. I see no reason not to connect the fridge to the battery side of the controller (i.e. directly to the battery) which will reduce losses a little.

In summary, I think battery 1 is tired and may not be making a useful contribution. (Maybe check this out by running the fridge directly off it and see how long it lasts compared to battery 2.) I think you need to avoid the voltage loss being introduced by the Waeco power supply, and, less importantly, the solar controller.



Hope that helps,

Cheers

John

Thanks John - I suspect battery 2 may not be well - but I will leave it for a while.

I decided to rewire & I have used 8mm wire

Rewired Redarc to tray with 8mm to Anderson Connection
Mounted battery 2 to Camper thus doing away with 2nd Anderson connection and shortening wires - used 8mm as well.

Wired Rectifier straight to batteries using 8mm and not through Solar Controller.

Test shows 12.3 volt at batteries and 11.8 at rectifier outlet, this now stays the same when I fire up the fridge.

If I fire up the car or run the smart charger I get around 13.4 at the batteries and 12.9 at the rectifier outlet.

It seems that this .5 voltage drop can not be altered, but the system may now run without issues (Depending on the battery condition)

I appreciate the effort in your reply's - Cheers Tony

I have the smart Charger on them now - when complete I will get them tested again - Thanks

Pouchy - Ta for that research - the web is a great thing - Cheers

Thanks Brenton - Maybe I will go bigger on the wires - Ill need another Ute to carry the load :-)

Moose - It appears they may not have been - I do not know how or even if they did test them, that is what I was told when asked how are they? :-)

They are on the smart charger at the moment saying fully charged, will go and do some more tests - Cheers

Ta Ian - Both batteries are 2 years old, they did sit around a while without use.

Will test them again early next week and post the outcome. Cheers

Does the CF80 have the adjustable voltage cutoff switch?

Ian - Have no idea to tell you the truth :-)

I gather you are saying if it did I could set it to cut off at a preset voltage.

I think it is all automatic, thus you have 5 stages of warning lights.

Cheers

Just reading the post and think Ian got it in one. 7 amps per hour on freeze wouldn't take long to flatten the batteries to the limit of the cutout on the compressor.

If you download the manual from the Danfos site you may find the standard form cuts out at 10.5v. You could change the diode to a different one to change the cutout. Your Waeco would stop at a higher voltage and your bait not freeze anyway. More battery power and better charging capacity than your 80w solar that will charge 4 amps for part of the day. Your Rodeo may not pump the 14.4V required to get the batteries bulk charged.

Thanks Ian & John - Looks like I will add another 100w of solar into the system a bit later on - This trip I will take the Yamaha 1kva :-)

I will load the fridge with frozen goods and bring it down on 240v.

Last trip across & around the South of Australia the fridge held frozen goods for the whole trip 6weeks

So once down to temperature obviously not as much as an issue.

Cheers Tony

Tony,
hope you 'test' the new wiring system before you go away and make sure it is al working perfect for you

Check the charging voltage at the more distant battery and make sure it's in excess of 14v.

Maîneÿ . . .

Ta for that - I went to our Local 12v guy in Mareeba and he suggested this was a good way to go.

But he also suggested that since I had all the gear in place adding another charger may not be the way to go.

I purchased 8mm wire and have rewired from Redarc through to batteries and removed 1 Anderson Plug. I also wired straight from the rectifier to the batteries and voltage drop is now acceptable. I now have 11.8v at the fridge and get 13v if I run the car or use the smart charger.

If this does not work he said it may be that one of the batteries is indeed a bit tired - If not we will go your way as well :-)

Cheers

Tony,
Why not ask the local autolecy if he can upgrade your alternator regulator to at least 14 Volts so you get better voltage at the fridge and distant batteries.

Maîneÿ . . .

Mainey - THANKS FOR THE REPLY ABOVE - I was going to answer that when I saw this reply.

I am going to check that agian tomorrow - one of the last readings I did was what was coming to the tray - I was in a bit of a hurry so just did a quick reading and it was reading 13.9 at that time.

If the alternator is delivering that - I think I should be good to go

With the 8mm wire I still get the .5 drop through the rectifier but the worst reading is now 11.8v

Thanks for the effort - appreciated. Cheers Tony

Hi Tony,
If your going to re-wire,i would suggest a min of 13mm2 wire.
I have a charging problem of zero volt drop at rear of the patrol
but it take's a long while to re-charge the battery in the camper.
It was explained to me like this,
Take a garden hose and fill a bucket.
Now take a fire hose and fill the same bucket.
Both have zero volt drop but one flows more amps? than the other.
I hope this helps.Maybe some one could clarify this method.

Cheers Ian.
I'm in Cairns.

Ian,
I agree thicker cable is better for the distance.

I was in Cairns last week, beautiful 28° days and 20° nights

Maîneÿ . . .

Thanks Ian & Mainey - You are a bit late - I went with 8mm - Ill see hoe that performs & go the 13 if I luck out now :-)

Should be right for our Simpson trip as we will only have a 2 night stay a few times & this time I will take the Yamaha & use the smart charger if I have trouble.

Cairns is great this time of year - come up here to the Southern tablelands and this arvo is the first time it has not rained this week - 200mm so far this week

Bog a duck on thew lawn again :-)

Are you heading further North John?

Regards Tony