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Balancing cells by dumping excess charge into resistors is energy inefficient. Here I present an alternative approach using oscillators, transformers and bridge rectifiers.

By Julian

Youtuber, shed dweller, solar charge controller aficionado

14 thoughts on “Battery cell balancing using inverters – energy saving”
  1. Avataaar/Circle Created with python_avatars Dan McKeown says:

    i mother

  2. Avataaar/Circle Created with python_avatars Michael Gronlund says:

    How much power is actually wasted in heat vs what makes it make into the pack?

  3. Avataaar/Circle Created with python_avatars YodaWhat says:

    IF you are trying to balance something with really poorly matched components, like random trashpicked lithium cells, this strange inverter approach might make some sense. But really, you'd be better off testing each of the cells, then grouping them into bunches with equal capacity, even if that means a varying number of cells per group. As is, the approach shown is like a old Roadrunner cartoon, where the Coyote if trying to propel himself in a bathtub held aloft by helium balloons, using a sail and a fan both mounted to the bathtub. If it worked, it would be perpetual motion. Of course, it WON'T WORK that way.

  4. Avataaar/Circle Created with python_avatars HMPirates says:

    You could strip down an active cell balancers that you get from AliExpress. They are about 12-50$ depending on the voltages. Search term is "active balancer"

  5. Avataaar/Circle Created with python_avatars nickt says:

    there are low voltage dc-dc isolation chips, eg 5v-5v. no point using the inverter that is "optimized" for 200+V

  6. Avataaar/Circle Created with python_avatars Tested to Destruction says:

    Think those things are aimed at being able to use simple 230v smps from your car… As you know a lot of smps (chargers and the like) will run from ac or straight dc so….. its my guess?

  7. Avataaar/Circle Created with python_avatars richardnanis says:

    Hmmm – i dont see much sense in this setup unless you want to balance the caps by hand? If you put 3 of the inverters – one on each of the caps – they might draw current simulanously from the caps and charge 50 or 60% back to the whole pack – wasting 40% of the energy in heat. I think there must be smarter alternatives for balancing…

  8. Avataaar/Circle Created with python_avatars Richard KB Formally FireballXL5 says:

    It probably has higher losses than the resistor across the capacitor so would not be green.

  9. Avataaar/Circle Created with python_avatars AdamSmith says:

    Interesting "food for thought" anyway.

  10. Avataaar/Circle Created with python_avatars Rob says:

    Instead of balancing by removing energy which sounds wasteful, how about individual charging each cell with a separate charger each. Perhaps some kind of arduino that pulses each cap charging and monitoring each cell one by one.

  11. Avataaar/Circle Created with python_avatars John Nicholson says:

    Hmmm, would it work with 18650 Li-ion batteries? Add a switch controlling computer as to do it automaticity. It looks like you can do this as it is charging also.

  12. Avataaar/Circle Created with python_avatars Sudipta Mandal says:

    pretty boring

  13. Avataaar/Circle Created with python_avatars Tony Wright says:

    Why not just solder it across the led so when the protection circuit comes on it turns your balancer on.

  14. Avataaar/Circle Created with python_avatars apb1111 says:

    If you want to preserve power to that level why not have your balancing buttons feed another super cap or li ion cell and have it run a light or something?

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