3.2V charger recommendations

[wlfpck1]

How do I charge a 3.2V Lifepo4 battery? I need to get it to 3.65v to be full charge. I need to top balance 4 of them to make a 12V battery.

 

[snoobler]

Resources tab is a good place to look for stuff:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

 

[wlfpck1]

Resources tab is a good place to look for stuff:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

Thanks, super helpful! If I use a benchtop power supply to do this, how will the power supply cut off and not overcharge the battery?

 

[snoobler]

The document you download from that page addresses the process start to finish in detail.

 

[lew]

Resources tab is a good place to look for stuff:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

I hope to receive 32 280AH lifepo4.Waiting. Top balancing will be a challange. I have 10a supply perfect for a few cells. 32p seems impossible. Suggestions?

 

[Dzl]

I hope to receive 32 280AH lifepo4.Waiting. Top balancing will be a challange. I have 10a supply perfect for a few cells. 32p seems impossible. Suggestions?

If you have a BMS you can charge in series until the cells are mostly charged or the BMS cuts off, then rearrange in parallel and finish top balancing in parallel.

 

[John Frum]

If you have a BMS you can charge in series until the cells are mostly charged or the BMS cuts off, then rearrange in parallel and finish top balancing in parallel.

Or don't break the pack but just charge the individual cells.
I just did it and it worked fine.

 

[lew]

Or don't break the pack but just charge the individual cells.
I just did it and it worked fine.

How many cells? Lew

 

[John Frum]

How many cells? Lew

8 cells.
1 cell took an ~1 hour, 6 cells took ~.5 hours each and 1 cell took ~15 minutes.

 

[Substrate]

I've used 3.2v single-cell chargers in various capacities from batteryspace.com before for LFP.

Just be careful you don't accidentally choose the nominal 3.6v for non-lifepo4, as those made for different li-ion chemistries will take things to 4.2v, and ruin your Lifepo4 !

 

[Substrate]

One thing to know is that a single-cell charger is convenient, but of course not as accurate as a programmable bench supply.

Ie, if you are relying solely on a typical 3.2v single cell charger for initial balance, you'll get in the ballpark to the point where your BMS balancers can quickly get things even better. Basically a 3% to 5% tolerance.

GWL even recently posted a blog about this on March 21st:

To be or not to be? - Balancing cells with a single cell charger​

So just in case anyone was wondering.

(update: removed other reference to a very OLD paper from GWL that is no longer relevant today.)