BMS disconnecting LiFePO4 charger at 14.0 volts

C

crashmaster

Advanced Member
Joined
Oct 1, 2018
Messages
66
Location
Girdwood, Alaska
Against my better judgement I bought a CCC (Cheep Chinese Chit) 100ah LiFePO4 battery. The BMS likes to disconnect the charger at 14.0V. I've tried it with 2 different 120V charge converters as well as a Victron 100/30 MPPT solar charger and all 3 get disconnected at 14.0V. Is this likely caused by a cell imbalance that can be corrected or just a permanently bad out of balance cell?

I figured I would try one of these Li Time cheap Chinese batteries somehow thinking that it would work ok. I used to spend quite a bit of time shopping at one of the big electronics markets in Shenzhen, so I should have known better.:unsure: Buy cheap, buy twice!

Thanks.
 
Last edited:
Sounds like a reasonable assessment. It went from 100% to 80% SOC in about 2 hours with the 85L isotherm fridge pulling 3.7 amps then stabilized a bit. My AGMs just died yesterday and I needed a battery today, so I took a gamble with a $250 Li Time. It might be ok for the price but I’ll try to return it when I get back home in a week. Might just go back to two 6V AGM golf cart batteries.
 
Last edited:
Does it have bluetooth? SOC according to what? A properly setup shunt or BT SOC at the BMS.

If so post a picture of it when you get the disconnect at 14v. I don’t have a LiTime, though my son does. I have SOK. But I think you are jumping to conclusions, as his battery does great. My SOK did the same at about 13.8vdc, it would go into charge protection, and then balance would come on. I left it on charge at 14.4, and it took 2 days, but got there, and balanced. Since then they charge to 14.4 (what I have my chargers set to) and go into absorbtion. You probably just need to top balance the battery.
 
Thank you for the reply, that is very helpful.

Yes its a bluetooth. SOC is according to the Victron shunt. The balancing has been on continuously on since I got the battery about 2 days ago. The bluetooth shows charge protection starting at 13.8V and the Victron shows it at 14.0V. Charge will resume when it shows 13.3V on the victron shunt, 13.5 volts on the bluetooth. However, today it did not go to charge protection until 14.2V, so its headed in the right direction. I have absorption set at 14.4 as well.

I think I will see how it does in another day or so. One of my guesses is that the cells are unbalanced and are slowly coming into balance.

I'm new to the LiFePO4 stuff, thanks again for your help.
 
That sounds good to me based on my experiences. Sounds like it is balancing out and things will be fine.

Best of luck.
 
As others stated, you can probably use one of the available apps to adjust the values on the BMS. Prepare for a ton of things you can adjust with those apps. I'm not sure I've ever really figured out what they all do but I did adjust the top end values, etc. that I understood. Remember too, not fully charging the battery will, over time, extend the life of the battery. You can go to Will Prouse's site and see what he says too. Great info over there. Good luck.
 
Continues to disconnect from charger at 14.2V which is ok I reckon. BMS continuously balances the cells and never stops according to the LiTime BMS app.

One thing I did notice is that running the 85L isotherm fridge overnight the battery will drop to 75% SoC using 25 amp hrs. The previous AGM dropped to 90% SOC using 10 amp hrs. This is around sunset until sunrise time frames and similar outside air temps. That was pretty interesting. I also notice the LiFePO4 takes longer to charge up to 100% SOC than the AGM did. Not quite what I expected to see.
 
My Isotherm fridge draws 3 amps and runs 1/4 to 1/3 of the time in warm weather. In a 12 hour period that would use 9-12 amp-hours. That is consistent with your experience with your prior battery.

Is your battery monitor set properly for the capacity of your new battery?
 
Last edited:
Also check the SYNCHRONIZE setting in the Victron Shunt. Maybe it isn't calibrated at the moment, and resetting shunt will get a different result?
 
Do you have a reference for setting up your shunt? I used the setup shown at
www.currentconnected.com

SOK 12V 100Ah LiFePO4 Solar Battery | Current Connected

The SOK 12V 100Ah LiFePO4 Battery provides ample power capacity with its 100Ah rating, ensuring a reliable energy source for your applications!
www.currentconnected.com www.currentconnected.com

My dometic 65L and 1 fan on low consistently would use 20% of my 100ah battery over night from loss of sun until morning. This is summertime. Winter it’s much lower. I now have 200ah, so 10%.

My agms couldn’t make it to morning.
 
Thanks for the feedback. Thats nice your battery webpage has the Victron settings. The LiTime website does not I suppose I could use those settings as there couldnt be much difference between the brands.

The BMV is set for the new LiFePO4 and calibrated the shunt at the last full charge before using the fridge but I will re-calibrate just make sure.

Also, the resting voltage after a full charge is 13.29V according to the Victron monitor and the LiTime BMS App. Thought that might be a little on the low side.

I'll keep testing it out some more.

Thanks for the help.
 
Last edited:
Oh, and I was suggesting you use those settings for the LiTime for charge and shunt. They should work fine. I don’t charge all the way to 14.6, but 14.2.
 
As an option: Current connected has SOK batts non-BT for $195 right now. Really don’t need BT, TBH, if you have a shunt. Their support is great, they are a small US based reseller of SOK, which adds peace of mind vice dealing with SOK over email/FB from China. They also have BT and heated, but don’t think those are on sale.

Can you send the LiTime back???
 
LiTime won’t take the battery back yet. I am communicating about the issues I have but they insist that it’s normal. Their manual says resting voltage should be >13.33, mine is 13.29. BMS won’t let the battery charge over 14.2, they tell me that’s ok. The manual says 14.4 +/-0.2

Using 25 amp/hr for one night of the fridge is not normal as my AGM used roughly 10 amp/hr.

I’ll keep working on them and see how it goes but I am skeptical of their customer support. They take 24 hrs to respond to each email. They don’t allow messaging, and the phone number to dial is in Shenzhen.

If I’m stuck with it I’ll deal with it since I bought it against my better judgment so it’s my fault. Given their responses so far and the amount of time it takes for each communication I probably wouldn’t buy again from this company.
 
Last edited:
I'll just add that 10AH is very low draw for my fridge. I'd say typical usage on a 80* day and 45* night is about 40ah. That's 130L Indel based fridge, LED lights, charging phones and running a small USB fan.
 
Thanks Vic thats good to know.

Has anyone had a issue with the BMS blocking the current of one battery when 2 LiFePO4's are wired in parallel?

I have 2 of these wired in parallel and only one is supplying current to the load when looking at both BMS's.
 
You must log in or register to reply here.

Similar threads - WTW

bajaphile
SOK LiFePO4 100amp-hr Battery @ 0%
rubberlegs
rubberlegs
K7MDL
Installed Renogy One Core monitor and Battery Shunt 300
K7MDL
K7MDL
K
Finished LifePO4 build (observations, cost, BMS, DC to DC charger
kmcintyre
K
J
New Lithium Battery – Some Assembly Required
Jack
J
P
FWC Electrical basics and upgrading to lithium!
7 8 9
ckent323
C

New posts - WTW

Back
Top Bottom