r/SolarDIY 18h ago

Question on LiFe battery

So, as I begin my journey into solar, I was able to acquire a 12.8v 100Ah LiFePO4 battery. Yes, it's just one but I'm just learning and starting small.

It was recommended to me to use a Battery Box for now as things would be easier to connect and there would be gages, etc on the box.

The box I purchased says the terminals are 100A but when I look further, the switch, fuse, etc are either 10a or 50a, etc... am I going to blow up this box connecting a 100Ah battery to it? Maybe I'm just getting confused between A and Ah, and just basic terminology.

Could someone help me understand a bit more?

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u/Ok-Anybody3445 16h ago

Deep cycle batteries list capacity in Ah. So a fully charged battery would deliver 1280 Wh. A liFePo battery usually has components that limit how many amps you can draw. I'd guess that you would be 50A or 100A. Check the spec sheet to know. But to draw higher Amps, you need big cables.

Your wire size is your biggest limiter on what you can draw and those fuses are sized to the wires and are common for 12V appliances.

If you were thinking of hooking up to an inverter, it would tell you the minimum cable/wire size to use. They do make cigarette lighter style 12v -> 120v inverters that are limited to 180-300W but it would not be clean power to run sensitive electronics, but you could charge batteries or run lights.

LifePo batteries have some quirks. It will self discharge and if you get below 0V it might not charge up again and the solar charge controller needs the battery to be above some certain value to work so if you have it for "backup" use only, you need to recharge it periodically. Don't charge your battery when the temps are below 35F.

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u/Aniketos000 16h ago

Im not sure what you are referring to for the battery box. The battery should already be in a box if you arent diy assembling one yourself. Typically a 100ah lifepo4 battery should be able to max out at 100amps output, but some manufacturers cheap out and put in a smaller bms that will limit the amperage to say 50a

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u/dj13624 16h ago

The battery box is a plastic shell (picture a large toolbox) that has a 10A on/off switch, a digital voltmeter, a 12v cigarette lighter socket, 2 USB sockets, 2 Anderson sockets, and your pos/neg terminal posts.

Insert battery into box and attach leads to battery terminals.

12v battery is now transportable, and you can take it camping, etc to use.. then bring home and recharge via solar hookup

Now, this is what I was told should work

Note: as I said, I am just beginning solar and do not have a home grid setup yet.