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

Top Balancing LiFePo4 Cells using a low cost benchtop power supply. 2023-09-03

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.

Reviews for accuracy, completeness and clarity are requested.

* I understand that this is a highly debated topic. I am just trying to share what works for me.

* This procedure is in line with the @Will Prowse Top Balancing video:

Video included for reference. Overview only. See PDF for important details and step-by-step instructions.

The following are edits I have made since I published the original document.
  • Appendix F: Edits from original version.(Most recent change listed first)
    • Throughout: Minor formatting and typo updates.
    • Section 4: Added Link to @Will Prowse’s top balance Video
    • Section 3: Added and then updated note about starting with cells that have significantly different SOC.
    • Section 5: Added the “Other Opinions” section.
    • Section 4: Added note about voltage drift after top balancing.
    • Section 1: Added link to @Will Prowse’s tools page for his power supply recommendation.
    • Section 5: Added reviewers concern about letting the current go to zero at the end of top balancing.
    • Added appendix that notes some people top balance by charging individual cells.
    • Section 2: Added comment that if you assemble new cells and a capacity test indicates full capacity, the cells came balanced and further balancing may not be necessary.
    • Section 3: Added note about getting cells close in voltage before putting them in parallel.
    • Appendix D: Added appendix about DIY power supply leads.
    • Section 4: Added image and text about hooking up the power supply to diagonal posts on the cells.
    • Introduction: Added warning to be careful of cell terminal threads.
    • 5/29/21 - Appendix D: Added comments about wire size and type.
    • 5/29/21 - Section 4: Added note about target top-balance voltages.
    • 5/29/21 - Section 1: Added note about Power Supply Amps
    • 5/29/21 - Section 1: Added note that a higher voltage supply would be needed for pre-charging cells for 48V systems.
    • 5/30/21 - Section 4: Added note about being patient with the process and about leaving the cells unattended.
    • 5/30/21 – Section 3: Added note about power supplies for pre-charging.
    • 12/29/21 - Section 3: Added note about checking cell voltages at the end of the pre-charge to determine if top balancing is necessary.
    • 12/29/21 - Section 4: Added note about not letting the cells sit at the balance voltage longer than necessary.
    • 12/29/21 – Corrected grammar and spelling throughout.
    • 9/3/23 – Added appendix on using an active balancer.
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Well done, very thorough, this has helped me tremendously, many thanks
Thanks for the tips ;)
Wow thanks for all the information in one place !
i found these errors in page 2:
"then you are more likely to get BMS High Voltage cut-offs with a 150V delta. However, if the charge voltage is going to run at a conservitve~3.5V/cell"
must be 150mV not 150V
and conservative not conservitve
Please place greater emphasis on the actual need for fabricating improved leads, how crappy the factory ones are, and that they may cause an already long process to be 2-3X as long. Include wording to indicate the following: 1) "Cells may ship as low as 30% charged. If you have 4X 280Ah cells, that's 0.7 * 4 * 280Ah / 10A = 78.4 hours of charging at 10A."; 2) at these low charge currents, cell voltages may barely budge for days at a time. Don't be surprised if you don't see voltage increase for very long periods of time. If you're still showing current on the power supply, and there is no heat or swelling, it's still charging."
Nice, good job
Thank you for compiling sir!
Great tutorial, thank you. This is exactly the way I do it and advise people to do. I wrote a similar tutorial in french and was asked to translate it in English - no need anymore, I just point to yours.
Excellent, this is very -very helpful! I love Will's videos, they're what got me here. In addition, I need this kind of methodical step by step tutorial to really help it sink in. Also, this gives me something that I can easily follow when I get my cells and assemble my battery. Many thanks.
Excellent how to for beginners. You can't go wrong if you follow the directions to the letter.