Need 12s charge/discharge BMS for dual mountainboard project *EU*

I am looking for BMS that will protect my lipo packs when riding.

in theory one motor can take up to 65 Amps…but this is maximum :slight_smile:

Pretty sure the BMS is for the battery only, not motors. When the ESC asks 10 amp from the battery, it’s not directly 10 amp going to the motor. Amps get “processed” by the ESC :wink: I’m only a user of VESCs but i guess it’s the same for MTB ESCs.

So to scale your BMS, you need to check the discharge values of your battery, it’s in its specs. What kind of lipos do you have in your build ? Any link maybe ?

3x Multistar High Capacity 10000mAh 4S 10C

Not a big enough c rating for mountain board unless your not going up any hills

Not really enough C rating for a street board either if you want my opinion.

1 Like

10Ah x 10C (100A constant) is not enough? o0

It’s not really 100a, it is overrated.

All Lipos are overrated except these:

well…good to know :slight_smile:

I was also thinking about using Li-Ion cells from electric Volkswagen E-Up! cells are 25Ah 3,7V each :wink:

That is an option however, you’ll probably need something like a 12s6p for a EMTB. You need headroom for amp draw. If you draw 100a from a 100a battery, you are likely to see some heavy voltage sag.

I think that Li-ions are more suited for long range batteries and Lipos are more suited for short range compact high output batteries.

10000mah 10a x 10c should give you 100a charge rating but I bet that pack can’t be charged at 100amps either the charge rating gives you more accurate view of its discharge ability

Click the spec tab in that battery from Hobbyking 2a charge and 10a discharge rated

Trusted and nice warranty

ok guys, but explain me one thing:

below, you can see my configuration of Focbox, you can see, that max Amp usage from battery is 30A (I am going to lower it anyway, too much power in my opinion :wink: )

that means, that this setup is taking 60A tops

…so how is it in real life according to this battery setup?


Guys? @Namasaki @Geoalex @Slak

You will draw that max amp only when u accelerate hard or drive uphill. While coasting you dont Need much power and while braking you gain a bit.

i am looking for a 12S charging only BMS… so if someone…

As others mentioned before, the “10C” feature from your lipo are overrated. So let’s be nice and say the real discharge rating is 5C, then we have 5C * 10000Ah = 50A. It’s, in theory, the maximum amount of Amps you can draw from your battery (and when you do, voltage drops so much, you and your board won’t like that).

In your settings, if you set 30A as Batt max on each ESC, it will be 60A total, which is above the 50A we calculated (base on my “5C” assumption, but for “7C”, it’s 70A which is still not really good). Those lipo batteries you linked before are not good for esk8 or MTB (as Geoalex and Namasaki told you already). You need to look for lipo adapted for our machine’s need (25C to 35C for Lipo is good IMO, but it’s still overrated :wink: ). Problem is not that the MTB won’t work at all, it’s just that it will be in bad situation on hills, maybe on violent starts, etc…and on the long run, safety of the hardware or yourself can’t be guaranteed (if you push your hardware too much, it will rebelled against you one day. Be cool with it.)

like 5ah… its nothing

All lipos are overrated except the pricey ones

Yep I know but I assumed that if OP bought from HobbyKing, he either doesn’t have the budget or is not interested in pricey solutions. So I didn’t mention it as Namasaki did before already.

ok guys, I get that, but, at least for now, I ended with 7 Multistar 10Ah 4s batteries. In that case I want to make them useful somehow

So I thought, that it will be good to protect them from overdischarging by using BMS. With a batteries like this it is almost 100% sure that some of cells will sag during riding. I was going to order 12s 80A Bestech BMS what do you think?