DIY 6S to 12S BMS with CAN - DieBieMS

Thank you! The cad files are already in your github folder. I modded the lid to make the top flat to make it easier to print :slight_smile:

I’m planning a setup where i mainly need the regen braking. How is this units overcharge protection? Would it be possible to redirect the surplus power to another load?

Well this is an interesting question, currently, no there is no alternate path for power than the battery.

In the future I would like to add regen power dissipation in a resistor. This will become an add on. I am also curios on who will need it :sweat_smile:.

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Would this feature require much work? :roll_eyes:

I would like to test the use of regen braking to add variable resistance and braking to rollerskis. Currently you order wheels with set resistance and you to skid to brake resulting in heavy tire wear.

I f-cking PROMISED myself I wouldn’t do this, but (-sigh-) can someone help me understand the balance wiring for two 6s lipos with 6 black and 1 red balance wires per pack? I’m looking at the github now, Ive read the diagrams thread, my instinct and research leads me to think it is column “c” below:20180720_060328

I’m a complete idiot, and I’d rather not eat-it here. Input is respected and appreciated, thanks you-people Edit: @JTAG @deucesdown @Namasaki

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Haha I can imagine the frustration :hugs:.

Balance wire mounting is always the biggest frustration.

Could you please draw the main current wires as well?

For the lowest pack you do need to connect the gnd wire of the balance Leeds. For the top pack you can indeed leave the gnd(with respect to the top pack) wire open.

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I’m also quite confused about setting up the balance wire connector…

There is 2 grounds GND, and I don’t know what the T1, and T2 are

At the top end (close to c12) of the balance connector there are GND T1 and T2, there are optional battery temperature sensors. You don’t need to connect them.

You start numbering/connecting from the lower end ( the GND close C1.

So in every battery all cells will have both sides connected to the BMS trough the balance Leeds. Also there are two main big wires that carry main current connected between the main terminals of the battery and the pack- and pack+ of the BMS.

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The MAN himself!! Thanks for taking the time to reply. So in this “c” column, wire 1 of 14 is gnd 1 on pcb, wire 2 is c1… wire 7 is c6, wire 8 flops around unprotected lol, wire 9 is c7… w14=c12? Edit: better lighting 20180720_082453

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No problem! Column B and C are both ok, but C has my preferende.

Column A will result in smoke :sunglasses::sunglasses:.

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This looks good to me (column C).

I usually build harnesses and adapters so I can split the pack and use hobby chargers to check capacity/health and rebalance. But it takes more space and is more delicate.

rofl is that a penis?

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Shown actual size too

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Before connecting the balance connector to the BMS please please check with a multi meter with the black lead on the GND and the red stepping from C1 to C2 to C3 to C… whether you get incrementing voltages.

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Haha if it’s to scale you don’t need a multimeter to check voltage

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Better penetration and resolution (sensitivity lol)

@JTAG @deucesdown and a phone call from @Namasaki , your input has been enlightening. Collectively you have bridged the gap between what I was pretty sure of and what I’m pretty confident of. Hopefully my understanding will help somebody else in the future! Thanks guys

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@JTAG I have a question about the precharge circuit on this bms. I am using a huge capacitor pack, which is 23Farads. Is that going to be problematic for the circuit? Just wondering if there’s a limit to what the e-switch can handle

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23Farads? On the load side? Or as a battery?

23Farads it not an intended load for this bms XD you might have to upgrade to a higher values pre charge resistor and change the pre-charge timeout value in the source.

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Lol, yeah they are rather ridiculous. I had a feeling that might be a problem. I’ll probably use something smaller with the bms. What size resistor would work for this cap pack? Or maybe about a 7F pack?

What are you doing with Farads as caps on the load side of the BMS (picture! :stuck_out_tongue: )? why are they there?

I do not have the bms installed yet. The capacitor pack is inline between my batteries and esc’s (as close to the esc’s as possible). LOL, you’re right to question that though, definitely not the right place to put them.