Still confused with bms:(

ESK8 Electronics
1

Hi this is my second post about bms and i am still as confused as i was…I am planing to build my board in the future but i am stuck with choosing my bms.I will be running my board on 2 6s lipo 20000mah 12c 24cmax batteries in series.2 6384 170 kv 80a motors and for the vesc the focbox unity.What i don’t understand is how many amps my bms must be…I am happy to read all your answers:)

2

I’m assuming you’re using Li-Po’s but could you post a link to the specific batteries you’ll be getting?

3

Yes sure

https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html?wrh_pdp=7

4

If you discharging through the bms its best to have something that can handle the current youll be sending through it so something like 80 amps or higher should be fine

5

I was planning on getting this but seems like i need a bigger one:( https://miamielectricboards.com/shop-1/12s-bms

6

Well, ur battery’s max amp discharging is Ah x c (20 x 12) = 240 But this is max discharge, usually it’s better to use half what you have to make it last longer. So basically u have 120 “safe” amps. What I would do is buy 200 amp bms, because you have 2 x 80 amp motors, which is total is 160amp.

7

Also I think it would be safe to use 160 amp from battery, because you only will be using it in very peak situations, which will happen very rarely. But see what other people say, bc I’m not a big geek in it.:+1:

8

Sounds good.can u suggest me a good bms?

9

I agree with @Aleks1

10

the problem is that 200amp bms is gonna be big, if it’s not a mountain board

11

It is a mountain board;)

12

people say Bestech BMS are good, and also I use Bestech but mine is 12s 80amp

13

https://buildkitboards.com/products/bestech-bms https://buildkitboards.com/products/bestech-d140-charge-only-bms

14

he needs 200amp

15

Thats what i was gona say:D I cant find any bms with more than 100amps:(((

16

You can’t run 100-200 amps through 12awg wire constantly. Your likely barely ever to pull 80A on an eSk8. Constant will be much less, less than 20a.

You can bypass with the D140 I linked, or get the 80A with eSwitch

17

but the idea of 2 80amp motors was strange in the beginning)

18

They dont draw 80A constantly, thats just their peak power.

Same with the batteries… if you discharged them at their max rate you would barely be able to ride. You can limit the battery amps in the VESC tool, just do that and get an 80A BMS or D140 and dont worry about the discharging.

1 Like
19

Ok lets say i go with the 80a bms with the switch how do i conect it if there is no dischsrge?

20

his bat max is 240 amp, pretty sure he can use 160amp sometimes with no harm for bat