Making an adapter to make 5 x 2s into 10s

As the title implies, i’m trying to make a harness or adapter, whatever you call it, to wire all 5 of my 2s lipo’s into series. Does this look right?

I just want to make sure this is correct before I end up killing my batteries and causing a fire lol.



Thanks for the vid, but in this case your only using two cells in series, when i’m trying to use 5. Hence the reason why i’m asking if the harness I poorly drew above is correct. Is it?

The number of series is irrelevant. 1st negative is main negative. Positive to negative till the end and last positive is main positive. The concept is the same no matter the numbers. Your drawing is correct. Just catch the essentials of the harness. With the method described at the vid you can switch series to parallel in a second. That’s the point.

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looks fine for discharge, but you’ll need to break it all up to charge, unless each pack has it’s own BMS :beer:

Or you can just wiree a 10s BMS to the whole array. You basically drop one of the balance wires between each pack - e.g. use wires from cells 1 and 2, drop the third on the first pack, then use the wires from cells 3 and 4, drop the third wire from the second pack… and keep going like that until you get to 10 and you do end up using the last wire.


@deckoz Dropping and sharing wires have the same effect - the cells are already connected together by the main discharge wires, so you don’t have to pair the balance wires too - you can just drop one half or the other.

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Hold on, let me draw you a picture.

Whether any of you is right, a wire is made available for safety. Use it. Worst comes it adds redundancy. Makes me think of some of my clients who remove the ground pin on electronics…“why did the surge kill it?”


@Flasher Yes, to a point - but these wires are redundant because we’re using the packs in a manner inconsistent with their intended use case.

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This is correct. When I wire BMS balance wires, I always leave off the black ground wire because like you are explaining, it is irrelevant. The pack, once connected, shares a common positive and negative, with each of the other cell balance wires finding its port in the balance connector. Essentially you are just dropping enough wires out of the pack to have a connection point between each and every “S” or series connection.

True. I usually pull the extra metal plug out of the connector so that it can’t possibly touch anything. I use lipo packs with BMS units and I don’t like actually cutting the real balance connectors off, so I solder a male side on the other end, thus I can pull the pin out of the male side to forego that connection :slight_smile:

I get what you are saying though

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