Damaged batteries (1 Viewer)

May 17, 2016
3,646
7,890
Aberdeenshire
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43,137
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B524
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2nd base
I got a low battery warning a couple of weekends ago. It had been a dull weekend for solar and I'd the heating on a fair bit but even so I was a bit surprised at the warning.

Had a look through the victron smart app history and noticed 2 low voltage warnings and 1 high one...

Screenshot_20221203_194702.jpg


I think this coincides with when I found a loose connection at the fuse coming from solar mppt. But would that cause the low/high battery? I've not been off hook up long enough for anything to take the battery that low.

Today I switched off the mains and watched the battery voltage drop from about 13.4 to 12.5 with a draw of TV and heating (about 3.5a) in around 5 minutes.

Are my batteries damaged from whatever caused the drop to 10.45v?

2 victron 90Ah gel batteries in parallel.
 
Jan 19, 2014
9,435
24,928
Derbyshire
Funster No
29,757
MH
Elddis Accordo 105
Exp
since 2014
I got a low battery warning a couple of weekends ago. It had been a dull weekend for solar and I'd the heating on a fair bit but even so I was a bit surprised at the warning.

Had a look through the victron smart app history and noticed 2 low voltage warnings and 1 high one...

View attachment 693809

I think this coincides with when I found a loose connection at the fuse coming from solar mppt. But would that cause the low/high battery? I've not been off hook up long enough for anything to take the battery that low.

Today I switched off the mains and watched the battery voltage drop from about 13.4 to 12.5 with a draw of TV and heating (about 3.5a) in around 5 minutes.

Are my batteries damaged from whatever caused the drop to 10.45v?

2 victron 90Ah gel batteries in parallel.
You'll need to watch them longer to see if they are kaput.
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
54,150
152,985
On the coast in West Sussex
Funster No
658
MH
Hymer B678 DL
Exp
Since 2008 & many years tugging
If the 10.45v was under load they will survive that, if it was off load not so good.
The 13.4v was because they have just come off charge Gels tend to hold a higher voltage for longer when they come off charge, if you left them for 24 hours they would drop to around 12.9v.
Bearing in mind 12.7v off load is considered to be fully charged a drop to 12.5v under load is quite normal.
 
OP
OP
monzer
May 17, 2016
3,646
7,890
Aberdeenshire
Funster No
43,137
MH
B524
Exp
2nd base
Thanks Lenny. Is the drop to 12.5v under load normal even when it happens that quick? It was literally no longer tha 5 mins after I unhooked power.

How can I test them?
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
54,150
152,985
On the coast in West Sussex
Funster No
658
MH
Hymer B678 DL
Exp
Since 2008 & many years tugging
Thanks Lenny. Is the drop to 12.5v under load normal even when it happens that quick? It was literally no longer tha 5 mins after I unhooked power.

How can I test them?
Yes quite normal, best way to test is on a slow discharge and test each battery separately.

First charge the battery fully and leave it to settle for an hour then:-

For example if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

1604657916224.png

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