Confirming information for new battery

[Hosinfefer]

Hey Guys,

Sorry for the long post but wanted to be clear in what I was trying to do.

I built a small 2 panel (2x265w) system going to an mppt tracer 40amp controller then to a 12V AGm 235amh battery which then connects to a 12 V 3000w inverter. I had no idea what I was doing with the battery but I guess im one of those dummies who likes to learn by trial and error. I ran the battery down a number of times to 10.5v as that is what the inverter shut off was and I thought it was safe to do so....yes I know now

So I have recently bought an lithium battery 12v and 400amp\h. As this chemistry is new to me I wanted to ensure I was charging this saftly and not kill it like my last AGM. I am looking for max lifespan so I understand I should charge to 13.8-14.0V and only discharge to 12.7. Is that correct? I am not really worreid about running out of load as I do have an automatic transfer switch which will flip my load to street power if my battery gets low. So would it be fine to just bounce the battery from say 13.-13.8? If it falls to 12.9 it will flip to street power and not bring the load back to solar until say the battery hits 13.8? Hope I got that right.

One other thing in my charge controller there are settings for charging. I cant find any good info from the controller to explain what these are other then it says to contact the battery manfuc. The new battery is from amazon and the Chinese company has not been very helpful in recommending what I should be using.

Below are the current parameters in question and what I am guessing I should be using with my new battery.

Over Volt Disc--14.8 New should be 14.0?
Charge Limit---14.4 New should be 13.8?
Over Volt Rec--14.4 new should be 13.9?
Equal charge--14.3 New should be ??
boost charge 14.2 New should be 13.7?
Float charge 13.6 New should be 13.6
Boost Rec 13.0 New should be 12.8?
Low Volt rec 12.6 New should be 12.7?
undervolt rec 12.2 New should be 12.7?
undervolt warn New should be 12.6
Low Volt disc 11.1 newshould be 12.5
discharge limit 10.6 new should be 12.5
Equalize time 120 Dont think I need this do I ?
boost time 120 Dont think I need this do i


Sorry if that is too long winded and thanks for any feedback.

[2BZ2Ranch]

Long time lurker first time poster, or poser.
Lots of info on Ron Collins' website https://marinehowto.com/lifepo4-batteries-on-boats/
Dave

[Mike90250]

What sort of BMS are you using with the Li battery ?

[Hosinfefer]

https://www.amazon.ca/Lifepo4-Lithium-Battery-System-battery/dp/B07SXK92SS/ref=pd_aw_sbs_263_1/139-4470968-5331508?_encoding=UTF8&pd_rd_i=B07SXK92SS&pd_rd_r=8b74e826-a4b0-4e8c-9109-98c9cd0af0dc&pd_rd_w=QSltg&pd_rd_wg=tRfFg&pf_rd_p=f18a7e04-315f-46de-b9ff-a824378e24c0&pf_rd_r=4C9JH405NCG82CMQD6DH&psc=1&refRID=4C9JH405NCG82CMQD6DH

it has a built in bms from the manufac.

[Mike90250]

ya know, if the seller cannot advise you as to the proper charging regime, I'd be inclined to look at another battery from a reputable seller.

[Hosinfefer]

https://www.amazon.ca/Lifepo4-Lithium-Battery-System-battery/dp/B07SXK92SS/ref=pd_aw_sbs_263_1/139-4470968-5331508?_encoding=UTF8&pd_rd_i=B07SXK92SS&pd_rd_r=8b74e826-a4b0-4e8c-9109-98c9cd0af0dc&pd_rd_w=QSltg&pd_rd_wg=tRfFg&pf_rd_p=f18a7e04-315f-46de-b9ff-a824378e24c0&pf_rd_r=4C9JH405NCG82CMQD6DH&psc=1&refRID=4C9JH405NCG82CMQD6DH

it has a built in bms from the manufac.

[Hosinfefer]

Sorry for double post. Yea they don't seem to be that helpful for the cost of the 400amp hour was a good deal compared to everything else I have been able to find

[Ampster]

[.]

it has a built in bms from the manufac.

I would follow the directions from the manufacturer. Any voltage decisions should be based on the chemistry of the battery. I would focus on bulk (constant current) Amps and absorb (constant voltage). Disable equalization and there is probably no need for float either.

[Mike90250]

The other thing that could be a red flag, is the battery is made up of used or counterfeit cells. Anyone in the biz for more than a week, has seen ads for "impossible" batteries with 10x the rated capacity of the best name brands, or seen the video of the "breakers" tearing the battery packs apart and applying fresh heat shrink to the working cells.

Have fun

[Hosinfefer]

I will pop the cover on my battery when I get it Mike and have a look at the BMS. Is there anything specific I should be looking for? I can measure the cells as well to see if this battery is made from junk.

[Mike90250]

I will pop the cover on my battery when I get it Mike and have a look at the BMS. Is there anything specific I should be looking for? I can measure the cells as well to see if this battery is made from junk.

Looking at it, is not going to tell a thing, unless they installed scratched up and rusty cells. It takes measurements to tell if it's a trojan horse.

[Ampster]

.... I can measure the cells as well to see if this battery is made from junk.

The resting voltage of a cell might give you a clue to what the chemistry is. 3.35v fully charged would probably be LFP as one of the links suggests. Closer to 4v most likely more volatile chemistry like found in most EVs.

[Hosinfefer]

Looking at it, is not going to tell a thing, unless they installed scratched up and rusty cells. It takes measurements to tell if it's a trojan horse.

yes Mike, I was going to take measurements. I know you cant tell by just looking at them. Figure of speech.

[Hosinfefer]

The resting voltage of a cell might give you a clue to what the chemistry is. 3.35v fully charged would probably be LFP as one of the links suggests. Closer to 4v most likely more volatile chemistry like found in most EVs.

Well the add says lifepo4, so isn't that lithium iron phosphate?

[Ampster]

Well the add says lifepo4, so isn't that lithium iron phosphate?

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?