I recently bought this 6S BMS from ebay. More specifically, I got th 6S 50A + NTC temp sensor BMS and I’m wanting to double check my wiring before I actually put power to it.
Here is the wiring diagram provided by the eBay listing:
Here is my wiring diagram:
In my testing before getting the BMS, my VESC has never reported a current draw higher than 18-20A. Any feedback would be extremely appreciated!
There should be 4 wires coming off each 3s lipo balance connector. The positive most wire will join with the next battery’s negative most wire to become bms balance wire number 3.
@marsrover you’re a life saver! Thanks for pointing that out. Does the charging barrel jack’s negative wire look good where it’s situated in my drawing or should it go over to the B-?
Its good where it is. (electrically that is) Physically I would run a wire from p- to the charge jack and a separate thicker wire from p- to the antispark. I assume you’ll have an xt60 or xt90 between the battery and bms and the antispark. Makes removing the battery module much easier.
I would also consider doing a charge only BMS setup if you live anywhere with hills as the regen brakes could overcharge the battery and cause the BMS to cut power. Suddenly you have no brakes.
I’ll sacrifice some batteries if it means I can have brakes until the batteries literally combust.
You bring up a really valid point! I was trying to think of the cons of having the current go through the BMS and wasn’t really able to come up with one. Admittedly, I completely overlooked how this could totally screw me over in a downhill scenario where power & brakes get cut by the BMS’s overcharge protection.
I suppose I could always “disable” regenerative braking in the VESC config if it ever becomes a problem. Fingers crossed it doesn’t. Thanks again!
If you disable regen braking in vesc, you disable brakes.
Your forward momentum is potential energy, to stop that forward momentum energy must be converted to another form. In the case of the vesc it puts that energy back into the battery. A little is also spent as heat in the motor and vesc, but for the most part 99% goes back into the battery.
Now other board manufacturers have tried using large resistors and heatsinks to overcome this, spending the energy as heat. But it’s just not as reliable as “don’t go downhill on a freshly charged battery”.
A few years ago I used an RC car ESC made by Castle and it used to make a horrible, loud noise whenever I would brake. I wonder if they were using that concept of spending the energy as heat.
Thanks for taking me to school on this stuff. This is all extremely valuable information that I would have otherwise had to learn the hard way.
You’re right in assuming that I would have an XT60 between the battery and BMS and the anti-spark switch.
@marsrover If I wanted to run my BMS as “charge only” as you called out, does this wiring look correct to you? Note, I left the negative of the barrel jack going to the P- of the BMS and ran a direct wire from B- to the negative input of the anti-spark switch.