6kwh of mystery LFP batteries

[schmookeeg]

Hi there.

This weekend I bought a multiplus inverter from someone second hand, and he tossed in 5 of these "victron AGM" batteries -- which are anything but.

I was pleased to get LFP instead of AGM. I was displeased to get "Rando battery" instead of victron, but they were effectively free so I'm now figuring out what to do with them. The specs seem optimistic, to say nothing of the dymo address-sized label being the only identifying mark

But I have no idea what these things actually are. And the LCD screen is a cheezy voltage meter only (found the exact one on amazon in fact). They came with 87% charge, so that's neat. They're light so LFP at least seems plausible.

Short of cutting one of these open, any idea how I can tell how best to identify or incorporate them?

Thanks for any ideas, or if you've seen these before and know what they are.

- Mike

 

[sunshine_eggo]

Parallel them. Charge them up to 14.4V and hold for 5 hours.

Put a 1200W load on the inverter and measure their capacity.

 

[HarryN]

The easiest way is to design them in at 30 - 50% of their max continuous charge / discharge rates.

So for example they list 50 amp charge rates - run them at not more than 20 - 25 amps.

Discharge similarly - it lists 100 amps continuous - so run them at 30 - 50 amps discharge rates.

I actually own a precision balancing charger to make batteries into matched sets.

Once they are fully charged and balanced then it is easy to determine their actual amp-hrs.