Is my BMS defect?


today i build my secound e-skate board with bms (hcx-d345) and 10S3P li-ion the bms output was 36V so it sounds good but after i conected the vesc to it the voltage was 2,4V?(the vesc did not turn on) I removed the Vesc and the voltage was again 36V :sweat:

sry for my english im german^^

Now i soldered the vesc to my power bench and it worked but why drops the voltage to 2.4V?

Be careful with these open solder joints, i don’t know how your BMS performs, but you risk a short of your battery.

Second thing i noticed is that you don’t have capacitors.

the caps are coming but i dont think that they solve the prob

If anything (like the balance leads) isn’t hooked up properly, it should cut off the output. Did you find a data sheet?


No, when i disconnect the vescs the voltage of the BMS is 36.11V but after i conect the vesc it drops to 2.4V

Hm…can you check the individual cell voltages? If the voltage drops as soon as any load is connected it kind of sounds like an unbalanced cell.

no the cells are all 3.6 V with or without connected to the BMS