SOLVED- Wiring BMS, bypass discharge 10S, anti spark- help please


I have read 10’s of posts about wiring BMS to bypass discharge and I’m still confused. I’m sorry to bother but conflicting posts have confused me ( red wire in balancing cable being last cell or that it doesn’t matter … etc).

I would be grateful for help with finishing of below drawing.

I have 2x3S Zippy 8000mah and 2x2S Zippy 8000mah to make 10S ( same C rating, capacity and make) , I also have colour coded cables from each battery as they are on my Zippy’s. Am I right that black wires have to be cut out apart of the one in first battery? or is it the reds? ehhh

My BMS is a cheap one from eBay - below is wiring diagram from the manufacturer.

As I’m adding Vedder anti spark switch it all got too much for me in terms of wiring.

Below is my drawing so far, please feel free to change it.

Thank you in advance!

I’ve got this so far but not sure at all it this is going to work.

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At a glance, looks right to me. Just make sure your cells are the same (like same capacity and C rating at least) so they don’t get too unbalanced since you’re using a cheap BMS. Using 5 2s batteries would have been easier to make sure of that but if you already have them and they have the same specs go for it.

Best thing to do is wire your battery up like you don’t have a BMS. Then wire up the BMS’s balance leads to the relevant cells. In this diagram, there’s no need to connect the B- to the BMS with the same wire you’re using as output. It need only be a thin balance wire like the others.

@darkkevind - just like that? Can I use the thin balance wire from last battery?It is connected with negative wire right?


@cricrithezar They all are same C rating, capacity, make and same supplier. I even checked voltage with multimeter and all looks good - same values, almost.

Yes, that’s fine. You can do the same with the plus as well on the other end. No need to connect to the output plus wire. Use separate lower gauge wires for the charge port.

True, it will be only small current, 2A max - my charge won’t give more. But the two main wires going to anti spark from switch and battery I’ll leave at 12AWG.

Thank you for your help @darkkevind ! I can finally go to bed after working this out for HOURS :slight_smile:

Yes, definitely leave them at 12awg :slight_smile:

If I have battery system with 2 10S sets of batteries in parallel for higher Ah, can I plug them to a 20S BMS even though they are not in series?

No. If you have a series of 10s you wire a 10s bms. What you want is that all connections are parallel between both sets @Moav

Be careful. Some bms require you to wire both the first balance cable to the balance connector AND the thick black cable to B-. I would wire both to be sure although they do carry the same connection to the battery

Otherwise you’ll fry it like I did :wink: make sure you connect balancing cables at the end !!! First all other connections

Omg. Did you actually fry if for that? I didn’t notice the dates. Sorry for piling up on your accident :joy:

I’m sorry I don’t understand which connection should be parallel, 2 BMS’s for both battery sets, then the batteries in parallel, and one power supply. Correct?

You can wire 2 packs of 10s lipo together in parallel to a single bms. Ill try and make a diagram later. Did you search the forum to see if there already is a diagram?

Yes, a dozen times, but I as well can’t believe I’m the only one trying that. This is as far as I know. I don’t know how to pass the BMS for discharge though I think I can get one that discharge at 100A or more.

You got the balancing part right there. Not quite sure about that power switch you have. Do you have a link for your bms so I can correct and add the output to vesc. Also what are you planning on using to turn on the board? Xt90s Loopkey? Antispark switch? If that is a normal switch in the diagram it is wrongly wired, and not the best option You are not the only one. I have nearly the same setup. The problem is my diagrams usually stay in my head. And you don’t want to go there and check. Trust me

LOL! that’s fine I love twisted minds…

So my power switch is an vedder anti spark with a power switch, and I’ve seen one of those BMS’s here somewhere but if you can suggest one with how to wire them to the batts that would be great!

Thanks dude

There you go. Choose either bypassing discharge or not. Only use discharge protection if your bms can handle the amps. I moved your vmeter after the switch. You can wire it where you had it but it would be on 24/7. I wouldn’t

Btw. If your bms is not marked b- p- and c- post a picture or a link and I’ll clear up


Oh. And your balance connector in the bms should have 11 wires. Tell me if it has less