Lithium ion battery - should i send one of them back

[mr-k]

hi all, i bought 4 lithium batteries, they are 12.8v 100ah, i was going to wire them in 2s2p, so have all 4 batteries in a 24v system. I havent done this yet, I bought them 1 week ago and have kept them indoors charging them with a solar panel and a victron mppt, configured for lithium and 12 volts. This is my issue, 3 of the batteries are holding 13.3 volts when left standing for 24 hrs, one battery drops to 12.8v, then if i connect it to a small 12volt fan, within 15 mins its dropped down to 12.6v, i assume that this isnt good and that if i was to connect this battery to the other 3 then they all would suffer. Can anyone give me their thoughts, should i send this one back or hang onto it - one last thing, were building an off grid system, that will run some of my home office stuff, looking at getting a motorhome next year, thats why i went for lithium thinking i could move them to the motorhome and probably get agm for the solar, were in derbyshire in the uk your thoughts on sendingthis one back

 

[RV10flyer]

yes, i would ask for an exchange.

 

[Texas-Mark]

Before returning it, I would make sure it is actually fully charged. You did not say what size solar panel you were using, And since you said you had 4 of them, not sure how long you had that one charging.

 

[mr-k]

Before returning it, I would make sure it is actually fully charged. You did not say what size solar panel you were using, And since you said you had 4 of them, not sure how long you had that one charging.

Hi, ive been using a 250w solar panel and victron mppt, i leave it charging all day until the victron stops charging , i am doing this one battery at a time changing the battery each day,

 

[mr-k]

Hi, ive been using a 250w solar panel and victron mppt, i leave it charging all day until the victron stops charging , i am doing this one battery at a time changing the battery each day, its been charging since 9.30, its a dull day andthe batterys gone from 12.6 to 13.1v the panel isnt in the sun yet, the victron was showing as it being in absorption mode, going to disconnect it now, if it goes down overnight then its going back

 

[Texas-Mark]

13.1v is as high as you have been charging it? Seems pretty low.

 

[TomC4306]

13.1v is as high as you have been charging it? Seems pretty low.

Especially for my lithium ion.

 

[timselectric]

"Lithium"
Lithium ion?
Lithium polymer?
Lithium iron phosphate?

Nvm..... just exchange it.

 

[mr-k]

13.1v is as high as you have been charging it? Seems pretty low.

Lithium iron phosphate type battery, 13.1 is the voltage accross the terminals using a volt meter when not connected to a charge controller for what i describe as the good batteries, the one i have an issue with is only reading 12.7v when not connected to anything, when connected to solar panel via the mppt, the absorption voltage is set at 14.2v, the float is 13.5, those are the default settings for a battery of this type in the victron charge controller,

 

[Texas-Mark]

13.1v is low for a resting voltage of a fully charged Lifepo4. This is why I question whether that "bad" one (or even any of them) are actually fully charged.

 

[Steve_S]

Just to clarify, How Many Solar Panels are you using ? One will NOT charge all of that ! You'll need at least 1000W of solar and that depends on your location & amount of Sunhours you get where you are.
The 2-Series & 2 parallel for 24V/200AH will require some respectable amperage to charge. A minimum of 50A from the SCC.

Set Absorb to 13.7V (3.425V per cell)
Set Float to 13.6V (3.400V per cell)

LFP Working Range is 3.000-3.400 volts per cell
@ 13.1V you are getting 3.275V per cell (about 60% SOC)

 

[mikefitz]

Hi, you are in the UK, who supplied the batteries?

It's possible the problem battery has shut off due to BMS protection. Charging from a solar controller may not 'wake up' the BMS. Connect an AC, mains, 12v battery charger and see if it accepts a charge.

Mike