Confirming information for new battery

[Hosinfefer]

Yes, so now you know the voltage. However we know nothing about the BMS and what other electronics are there to safely charge the cells. Do you have a multimeter?

indeed I do.

[Ampster]

indeed I do.

The max voltage you ever want to see LFP cells is 3.65 and for longevity I never took mine higher than 3.45 -3.50. An hour or two after charging they should settle at a voltage of 3.35 more or less. Charge your pack and see where the BMS cuts off the charging. That will give you a clue if the manufacturer hasn't put it in writing. Assuming you have 4 cells the max charging voltage would be 14.6 (3.65 per cell) volts for a test.

[Hosinfefer]

ok so assuming it is a 4 cell the max charging voltage should be 13.8 and then the BMS should cut if off. Would it be smart to set my charge controller a bit higher and see if the BMS cuts out the charge to protect the cells? Based on the above then the healthy resting voltage with no load should be 13.4 correct?

[Ampster]

ok so assuming it is a 4 cell the max charging voltage should be 13.8 and then the BMS should cut if off. Would it be smart to set my charge controller a bit higher and see if the BMS cuts out the charge to protect the cells? Based on the above then the healthy resting voltage with no load should be 13.4 correct?

You may need to try a little higher voltage once to see where the cutoff is. Later if you have an Absorb setting (constant voltage) then you could try that lower setting. . Yes the pack should rest at around 13.4.

[Hosinfefer]

i do believe also they send along a ac to dc charger for it. It will be interesting to see what their charge take the battery up too. Might give me a good idea for where they consider a "full charge". I think if its higher Ill stick to the safe side. I dont need the battery to be max as my load is smaller and not constant. Would rather keep the battery at 90% and save some of its life.

[Ampster]

i do believe also they send along a ac to dc charger for it. It will be interesting to see what their charge take the battery up too. Might give me a good idea for where they consider a "full charge". I think if its higher Ill stick to the safe side. I dont need the battery to be max as my load is smaller and not constant. Would rather keep the battery at 90% and save some of its life.

Yes that will be a lot easier than trying to coordinate with a solar charge controller which may have variable Amps. With that charger you may be able to tell when it goes from the constant current to constant voltage phase. Just track the voltage until it levels out and that is when the charger has transitioned from constant current to constant voltage. For your purposes in setting your controller, constant current is like Bulk in Lead Acid terminology and constant voltage is like absorb in Lead Acid terminology. If you can see the Amps from that charger they should taper off and hopefully cutoff as some low Amp rate.

[Mike90250]

When you are doing your testing to find the BMS setpoints, limit final charge current to less than an AMP, maybe just .5A You know you will be triggering the bleeder resistors, and in a "drop-in" box, no space for large resistors to dissipate the heat

[Hosinfefer]

So I got the battery in. Its 13.3V on arrival from what looks to be 8 cells. For individual cell voltage I can just probe black and red of 1 cell with my dc multi-meter 9AB9B4A8-7D38-4742-B703-436BAE239BB9.jpeg . I have highlighted the first cell to test with red arrows. I assume I don't need to disconnect everything correct?

[Ampster]

It looks like 2P4S. Dont take it apart. You might lose the warranty. Each of the small wires is a BMS wire. Lithium batteries usually dont ship fully charged. Note its resting voltage and charge it up until the charger turns off. Does it have any instructions or specs?

[Hosinfefer]

No for instructions or specs. I have emailed the manufacturer for that information. On a side note which I assume good is all 8 cells measure the exact same 3.331V. So i guess I dont have any really bad\used cells. Like you said Ampster, time to charge it up with the charger they sent at see what they are once charged. The charger says its 13.5v at 25.9A

Side note, do these battery off gas while charging. Based off what I was reading they say yes if caught fire, but under normal charging conditions am I safe to do this in a closet in my house?

[Ampster]

Side note, do these battery off gas while charging. Based off what I was reading they say yes if caught fire, but under normal charging conditions am I safe to do this in a closet in my house?

I would not charge a new and unknown Lithium battery in my closet. I do mine in the garage.
Normally they don't offgas like lead acid but if they are over charged you will smell an ether like smell. The vents are the white dots in the middle of each cell.

[Hosinfefer]

OK the first charge I will do tomorrow while I am awake and can monitor.

The reason I was asking was I want to move all my equipment (controller,inverter,transfer swtich and battery) upstairs from my crawl space to the main floor. In the winter the entrance to my crawl space gets snowed in and its a pain to have to go down and reset the inverter. Once the battery gets a few cycles I can maybe move it up into the house. Or maybe leave just the battery down in the crawl space but move everything else upstairs.

[Ampster]

Once you have verified that they are LFP then you can decide if you want them inside for convenience and warmth. LFP is the only chemistry I would have in my home except of course my mobile, my laptop, my Dyson vacuum, my Milwaukee power tools and who knows what else. All of the above are probably a lot more volatile than LFP..LOL

[Hosinfefer]

So i was finally able to track down their version of a "data sheet". Seems not as detailed as others I have seen. I guess they say CC\CV for charge type. CC I think is similar to bulk charge setting in my charge controller, but the CV setting....? Also the voltage stays at 13.3V even after charging it with their charger or 17hours.

Not sure why the data sheet spec's keep getting cut off.

[Hosinfefer]

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