Battery Dead or something else I should check? No.2 - Motorhome Forums, Motorhome Discussion, Motorhome Chat

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post #1 of 3 (permalink) Old 20-09-2020, 13:32 Thread Starter
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Angry Battery Dead or something else I should check? No.2

Sorry, if you are reading this twice, cause I posted it in another topic, and now see this feed as a more appropriate.

I have installed an Ective Solar Panel system in my 6. month old Campervan. It is connected to an 80 Ah AGM battery. My fridge is a 12 volt fridge.

After installing the solar panels several months ago, my battery voltage never dropped below 12.50 volts overnight. This I understand is using perhaps 30% of a battery capacity, so well within the 50% target to maximise the life of my battery.

The solar panel is always active and i can see from my App for the system that when the battery is full it correctly trickle charges, sometimes only topping up the battery with 5Wh in a day, (but mostly around 50Wh), when the fridge is off.

About 3 weeks ago, we went away for the weekend with friends.
I turned on the fridge Wednesday (Day 1) sometime to let it cool down.
Thursday (Day 2) loaded it up with beer.
Friday (Day 3) kept on adding beer to it to cool beer down.
Saturday (Day 4) opened my App and looked at the info.

Day 2 minimum voltage was 10.2 V
Day 3 7.9 V
Day 4 8.4 V

Next weekend, covered the solar panels and did a test. After 7 hours of running my fridge, the battery voltage 13.1 V(no load)/13.0 V(underload) to 12.9V (no load)/12.7 V (under the load of the fridge).
The next morning before I uncovered my solar panels, the voltage came back up to 13.0 V.So assumed I cooling down all the beer used more energy than I assumed the previous weekend and there was nothing wrong. All voltages were confirm with a separate voltmeter.

This weekend, headed away for the weekend. Saturday morning notice that the minimum voltage was super low again over night (I think 6.6ish V) and I got a low voltage alarm on my heating system.
Saturday night I did a test.
Solar panels stopped generating power around 7:30pm I guess. Battery voltage was around 14.0V.
At 1am the voltage with fridge running was 12.8 V
At 3 am the voltage drop to 12.0 V. I turned the fridge off.

When the sun came up, I turned the fridge on. And Solar panels charged the battery giving it 430Wh, which is similar to what was required to fill the battery up prior to this issue.

Sunday night, I turned the Fridge off when we went to bed with 12.9 V. In the morning, turned the fridge back on (still very cold) and turned on the diesel standing heater. 60-90 secs later, the LED's started to flicker and the heater switched itself off. Minimum voltage was 6.93V. The fan of the heater and the fridge killed it .

Other possible important facts:
- On really hot sunny days, sometime I will get an over voltage alarm on my heating, but my Solar system shows max voltage was 14.82 V, so assume the voltage spike is very short
- last week a few days before we went away, the fuse between my MMPT Charge controller and battery blew. Electrics in motorhome were switched off.
- all currents are well within the capacity of the MMPT and cables. Never seen the current above 20 AMPS. MMPT is rated at 25 AMPS.
- I know I have only ever drain the battery anywhere near empty once, before i installed the solar panels. After a day and a half, the LED indicator suggested it was about 10-25% capacity. I understand a AGM should be able to cope with 100% drain about 20 times?

Can anyone suggest if there is anything I can further test? How can i do a battery load test?
Could it just be an unlucky battery that I should claim under warranty?

Any suggestions would be appreciated.

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post #2 of 3 (permalink) Old 20-09-2020, 14:04
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No expert but I'd say your fridge is the problem, the 3 way fridge is popular for a reason, but as it's happened before I could be wrong.
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post #3 of 3 (permalink) Old 21-09-2020, 21:43
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Is it sunny every day in Hamburg ?
Not in my experience.

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