I'm kinda new to solar setups, and I have a question about my 48V 100Ah batteries that have been stored for around four months. I still need a few months before I can get an inverter and solar panels, and I know it's not great to have batteries sit without charging them for too long. My friend has a 58.4V DC 5A golf cart charger. If I connect my batteries in parallel and use that charger, will it keep them alive? Is that 58.4V too high for them? I'm just looking to charge them a few hours each week to keep them in good condition. Any thoughts or recommendations?
3 Answers
You should definitely consider the type of battery. If they’re lithium, the 58.4V may not be a problem, but it's on the upper edge. For lead acid or AGM, that voltage would likely be too high. However, given that a couple of months might not hurt them, just be cautious and monitor their condition.
If you have LiFePO4, I wouldn’t leave them connected to that charger all the time. It will keep them topped off at a higher voltage, which isn't ideal. Lithium batteries have a low self-discharge rate, so you'll find they can hold a good charge for several months without needing much attention.
First, it's important to know the battery chemistry. If these are lithium iron phosphate (LFP), they can be stored pretty well. Ideally, keep them around 25°C and at about 50% charge—around 51.2V for 48V batteries. Keeping them fully charged for too long isn't recommended though. That 58.4V from the charger is on the high side for long-term storage, so you're better off charging them to about 50% and checking them every couple of months.
Thanks for the tip! So keeping it around 51.2V sounds like the way to go. I'll check them periodically.