question

the-nook avatar image
the-nook asked

AGM gel batteries overheating ?

I have 12 batteries (in 4’s 48v), they have overheated today and bulged out.

However not all of them are hot.

2 are roasting, about 4 tepid and the rest cold.

All link by the same lengths of battery cable, as per the instructions that comes with the bmv700.

All going via pos and Meg busbars then to the multi plus.

Batteries have been fitted from new for 15 months.

However, this is the 2nd bank of batteries that this has happened to!

The solar guys that I got the batteries from have checked my VRM which was all good.

They even sent an engineer to check my system too, and no problems reported !!!!

All batteries sat apart in identical conditions too.

What the hell can it be ??

leisure batteries
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8 Answers
nickdb avatar image
nickdb answered ·

Impossible to tell over the internet.

Much more detail needed.

Wiring diagrams? Vrm charts showing temp, voltage, current etc.

Configuration settings?

This isn’t normal, so something is either incorrectly installed or configured, or both.

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Alexandra avatar image
Alexandra answered ·

Overcharging (aka charging too long)?

Too high an amp rate as well?

Not charging enough, then too much.

Just guesses, but those are the two main ones I have seen to destroy AGM and Gels.

Beginning at the beginning - shelf life before install also has an effect on installed lifespan.

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the-nook avatar image
the-nook answered ·

Thank you.

Settings are factory defaults

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the-nook avatar image
the-nook answered ·

Weather conditions 10 degrees C, raining, cloudy.

No huge draw on the system 160 w max.

System at 99.7% yesterday, back up to 100% today.

No warning on the system!!

Like I say, the systems been gone over by the solar guy I bought the batteries from.

Clearly if they could have got out of replacing the batteries, they would have done, so finding my set up at fault would have meant they wouldn’t have to pay out. They couldn’t find a problem!!

Neither could the Gus I bought the panels and victron easy solar 3kva from, it’s all been checked by their engineers via VRM.

I’ve selected the battery type they’ve suggested !

I don’t know who to go to 1st, battery guys or victron guys ???

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JohnC avatar image JohnC ♦ commented ·

@The Nook

Parallel battery strings need special attention. Read these threads, both fairly recent..

https://community.victronenergy.com/questions/173977/victron-super-cycle-agm-sizzle-and-smoke.html?childToView=273162#answer-273162

https://community.victronenergy.com/questions/95629/agm-super-cycle-overheating-problem.html?childToView=273133#answer-273133

Heavy resistance there from the posters, but almost certainly the cause of your issues too. All of the 'overcharge' comments are relevant, think of all that current focussing down one string. Been there myself, not a pleasant place..

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the-nook avatar image
the-nook answered ·

So, are we saying that the battery set up specifics, that set out by Victron, that I followed to the T, are wrong ?



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the-nook avatar image
the-nook answered ·

Battery set is identical to this.

img-7769.jpeg


img-7769.jpeg (573.8 KiB)
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the-nook avatar image
the-nook answered ·

Also, how can the batteries receive overcharging?

Shouldn’t the solar charger shut this down when it senses the battery is at 100%

Thank you got the threads, but I don’t have an alternator.

Just a very simple system, with no external inputs.

We only run off sunlight.

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christern avatar image christern commented ·
What is the maximum voltage the batteries have been charged with during their life?

What is the difference between the midpoint voltage and the endpoint voltage at max and min?

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the-nook avatar image
the-nook answered ·

Sorry about crude diagram, you may have to zoom in too!


img-7770.jpeg (4.0 MiB)
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