Battery Charger circuit for LiFePo4 12v 20AH battery ?

[bob4bvm]

Anyone have a circuit for this ?
I understand a lead-acid or SLA charger can be used, but i am unclear how the battery's built-in BMS comes into play here

Battery in question is a LiFePo4 12v 20AH . Used to power remote devices, so normal charge/discharge cycles.

Can i just use my bench P/S set to 14.5V with a current limit of 0.2C (4A) ?

Thanks,
Bob

 

[bob4bvm]

Stil looking for this one, anyone have a ckt ?

Am i posting this request in the wrong place here ?
Thx
Bob

 

[Tony Stewart]

Do you have a link to the datasheets? battery, BMS

It's hard to find the charger specs especially for undercharge>recovery method.
Normally Lithium needs CC then CV then cutoff when current drops below 2 to 10% of the CC rate to reduce wearout. I see 14.4V is used for the CV level. It is most important to minimize the time spent during CV mode at 14.4V for longevity because the normal resting voltage is more like 13.7 and this overcharge stresses the battery. Lower voltage limits are more forgiving like 14.0V. which may reduce capacity a bit but extend the total cycle life number greatly. (Ref Battery University)

https://www.amazon.ca/Lead-Acid-Maintainer-Automotive-Motorcycle-Cart-Repair/dp/B08P5YNP3M/ref=pd_bxgy_d_sccl_1/141-3405835-6554568?pd_rd_w=4EEBJ&content-id=amzn1.sym.93ae3f3f-3555-4971-a952-df8053b1d375&pf_rd_p=93ae3f3f-3555-4971-a952-df8053b1d375&pf_rd_r=K94E8SFWTQQTCT7VJ7Y2&pd_rd_wg=iNdQ6&pd_rd_r=daf9dda9-de9e-4160-badb-eb1348b90e9f&pd_rd_i=B08P5YNP3M&th=1

 

[bob4bvm]

Hello Tony,
Sorry i have not checked in here for a while
I have been using a simple 12V lead acid charger for a while now, seems to work ok. Output is a CV 14.5V, and my meter on battery shows an increasing voltage and decreasing current as the battery charges up . I charge at 4.0A max current.
Apparently the onboard BMS takes care of most of the charge issues that may occur.
Not a real spec sheet, but this is the best i have for the battery in question:

Thank you,
Bob

 

[bob4bvm]

Any LiFePo4 experts care to comment on what i am doing for charging ?
Thx
Bob

 

[Lightium]

It says right in the specs, "Charging Voltage 14.6V", "Maximum Continuous Charging Current 20A".

 

[bob4bvm]

Yes that's right, but i was wondering about the charge curve. Seems most chargers for this battery type use a varying pattern of CC/CV to fully charge the battery.
My simple charger is just a basic DC supply, no current control. As it works out, when i apply around 14.5V the charge current runs 4 amps. Battery seems OK with that , at least have not had the BMS kick out or do anything weird.

 

[crutschow]

The main difference between charging SLA's and LiFePo4 batteries is that the LiFePo4 should not be left on a float voltage/charge, so the charger should be disconnected when full charge is reached.
This paper should help.

 

[bob4bvm]

Thanks very much Crutschow !
After reading many similar but incomplete references on the subject, the paper you linked is a breath of fresh air
Finally a clear, concise explanation on the subject.
All the others invariably left some mystery hanging over the charging procedure.

It seems that no matter what i ask here, you are the one who comes up with the perfect answer for me !
Happy New Year,
Bob