Why Does My Battery Keep Dying Overnight?
Asked by StarrySky542
Hey everyone! I'm having a major issue with my off-grid battery system for a lake aeration pump. Every time I check on it, whether it's been a day or several, the battery is completely dead. It's a 280ah battery, primarily used during cloudy days since the pump doesn't run at night. I have around 1500w of solar panels connected through charge controllers. I thought the battery had a built-in discharge cut-off to prevent total drainage, but it seems like there's an issue. Could the inverter or charge controllers be draining the battery overnight even when everything is idle? Just yesterday, I left it with some charge left, but when I returned 20 hours later, everything was off again. My inverter has an auto shut-off for low voltage, and I've set my pump on a timer. Is there something I'm missing? Any insights would be appreciated!
Answers
From what you've described, it does sound like your new inverter could be the culprit, especially if it has features that allow it to idle or turn back on automatically. If the original issue was resolved by upgrading, it’s possible the new inverter is drawing more power when it's not actively running the pump. You might want to check the specs on that inverter and see how much it consumes in idle mode.
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It might be worth considering if there's a battery shunt in your setup. This tool can really help manage and monitor power usage. If you don’t have one, that's something to look into! It seems like they can clarify whether the inverter is idling and consuming more power than expected.
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First off, can you tell what type of battery you have? Is it flooded lead-acid, AGM, or lithium? That can make a difference since each type has different drain characteristics. Also, it could be a good idea to disconnect all loads temporarily to see if anything on that side is causing the drain. Try leaving only the charger and inverter connected and check if it still depletes overnight. If that doesn't work, disconnect the DC side to the inverter and monitor whether the charger continues to drain the battery.
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