I'm working on a project involving some custom LiFePO4 battery modules. They can take a very high current charge, and I'd like to take advantage of that. I have battery management and charge termination equipment that I've built or hacked together, and now all I need is a power supply to drive it all. I need 28.8v (±0.1v) with at least 30A. Since this seems to be rather difficult to come by (and fantastically expensive when you can find them), I figured I could build my own. But designing such a thing is beyond the scope of my knowledge. Can one of you guys help me, or at least point me in the right direction? Any help or advice would be greatly appreciated.

  • \$\begingroup\$ A123 pouch? What kind of cells? (just curious) \$\endgroup\$ Commented Jun 23, 2013 at 23:46
  • \$\begingroup\$ They are prototype modules from A123. They have 8 cells in parallel with built in BMS. I have some pictures here, if you're interested. \$\endgroup\$ Commented Jun 24, 2013 at 1:02

1 Answer 1


Building a 28.8 Volt @ 30A power supply (> 860 Watts) is not a trivial exercise even for an experienced power supply design engineer. Getting it to be accurate to 0.1V (+/- 0.35 %) probably doubles the challenge!!

This would not something that you could successfully "hack together".

I would encourage you to look around at some electronics equipment surplus yards to see if you can find a ready built 28V supply (28V DC was common in military, aerospace and some communications applications). Look for a high power linear power supply. These are usually adjustable (or can be modified to be adjustable). Linear power supplies can be adjusted up and down by a volt or so to get to your unusual voltage requirement.

One name to look for is Lambda. If you find the type of thing I have in mind it would likely look like this:

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  • \$\begingroup\$ I'll look around. It's interesting that 28V is a standard. The more I research, the more it seems like buying will be cheaper than building. Thanks for the tip! \$\endgroup\$ Commented Jun 24, 2013 at 1:03

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