Chins Replace or Discount?

[brclark82]

This is my first LFP battery, it’s for my RV, and I chose the Chins 250Ah Smart Heated battery.

I hooked it up today and the app states that it has a max capacity of 220Ah. I started charging it and when the app hits 220Ah it shows 100% and stops increasing total stated Ah but it is still charging and receiving amps into the battery for a couple hours so I assume it actually has close to the stated 250Ah advertised.

I contacted Chins and they said it was a known issue on some models and couldn’t be fixed. They offered me a replacement or a $200 credit (I paid $800 originally).

Last thing, throughout charging today all the cells were within about 0.01-0.02V until it started to reach maximum capacity and then cell 1 starting rising much quicker than the other 3 and hit the over voltage protection at 3.65 while the others are closer to 3.45.

Any recommendations on what I should do?

 

[BentleyJ]

The cells need to be top balanced over a period of time. Try float charging for several hours at a voltage just below where the OVP kicks in for that one cell and disconnects. Observe the cell voltages and verify the BMS is balancing the cells.
As far as the Ah rating 250 vs. 220, it shouldn't be a problem if the Constant Voltage portion of the charge is cycle is selected properly. I would recommend 3.5V per cell. When the battery is charged the current will fall off rapidly and charging should stop at about 2% tail current. Under normal conditions float charging is not recommended unless there is a load on the batteries then its OK as long as float voltage is low enough, 3.35V per cell, just enough to carry the loads and not continue to drive current into the battery.

 

[brclark82]

Ok, right now my only chargers are my MPPT and the RV converter. I plan to upgrade to a Multiplus sometime this year but for now that isn’t an option.

The converter sends it into OVP much quicker than the MPPT so maybe I will play with the settings on it to try and get them balanced.

 

[Supervstech]

So, 600 for 250Ah lithium! Wow.

 

[brclark82]

So, 600 for 250Ah lithium! Wow.

No joke, and it’s heated…I’m going to try and get the cells balanced and use my smart shunt to run a capacity test before I make my decision but that’s hard to beat

 

[brclark82]

Well I did a capacity test and got 247Ah before my inverter shut down for low voltage but the LVP never shut off the battery.

I fully charged overnight and then left my MPPT to absorb at 13.8V and the cells were much more balanced. Going to try and uo it to 14.2 today.

Oddly enough with one charge the app that they said couldn’t be fixed updated itself to show 240Ah instead of the 220 it was showing at first.

I went ahead and just kept the battery and the $200 refund.

 

[WorldwideDave]

Hello @brclark82 - is it still working good for you (the chins)?