question

tom-galletti avatar image
tom-galletti asked

Battery voltage dropping suddenly

Morning,

I've got 150Ah of batteries (wired up in 2 series arrays at 24V, arrays wired in parallel). Because the weather was rubbish yesterday my 300W of panels only hit 100W peak, but I went into the night with about 23V and discharging slowly.

At 3am, my batteries dropped from 22V to 14V in the space of an hour and everything went offline.

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Is this normal behaviour? If so, is there a way I can avoid it happening again?

My SmartSolar charger is a 100//15 so I could feasibly add another panel to help charge it, but that doesn't explain the batteries behaving weirdly.

discharge level
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1 Answer
wkirby avatar image
wkirby answered ·

23V is already really low, you should have stopped discharging at that point.
Battery discharge is not linear and the battery Voltage will drop a lot quicker at the end.

I'd recommend getting your battery recharged urgently to try and limit the damage. Running the battery as low as 14V will definitely have done some permanent damage and the long term lifespan will now be shortened.

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tom-galletti avatar image tom-galletti commented ·
Long term lifespan not a big concern at the moment!

The dead battery has been removed, the others have been recharged within 24h (however they did get as low as ~6V.)


Is it safe to leave these batteries connected after such a big discharge? Are they likely to kill the 4 new batteries I've just put in?


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