BMS Wiring & Loop Key Polarity

Hi just want to upgrade my board with a BMS and a XT90 Anti Spark as a Loop Key my questions are:

#1 for this BMS

How do I properly wire this thing up - bought it in China with no manual etc. Am I right with my guessing - but guessing is not the best :wink: B+ Battery positive B- Battery negative P+ ESC positive P- ESC negative ok thats pretty straight forward, but like to add a Charge Plug - but as there is no “CH” as on many others. So should it be: B+ Charge positive P- Charge negative And what is the one pin labeled with “D-” Balance Leads are pretty clear to me

#2 Loop Key with a XT90 Anti Spark I read a bit in here about that but still dont have a clear solution. Should it be in the positive (common ground would stay untouched) or in the negative (as the BMS works via the negative) ? Well “normally” it shouldnt matter where a switch is placed :wink:

Thanks and Cheers Marty

XT90 antispark is just a switch with resistor and resistor has no polarity, neither switch does. It doesn’t matter really matter where you put it. I personally prefer to cut common ground so I know for sure nothing is powered.

E: of course you want to put in between BMS and load, as @PXSS pointed.

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Loop switch needs to go between BMS and ESC on either lead. I personally put it on + You do not want it between BMS and battery as you would not be able to charge without the board being powered. (Could be dangerous)


yeah where it belongs is clear - between ESC and BMS, but as you see in the first two answeres - 2 answeres - 2 opinions whether in + or in - I know as in a house installation you put the switch in the “live” wire - whereas it phsyically wouldn matter :wink:

thanks anyway - any suggestions about the BMS wiriging and the confusing “D-” pin ?

Take a look at it’s datasheet ( if Or try to find something using google images… You can search using an image :slight_smile: In the worst case, you can always ask seller for help :smiley:

Hope that helps.

yeah thanks - I searched google & pictures in advance a lot, but just also came acrros these simmilar ones. Datasheet - yes nice - but only values and specs ask seller - yeah if someone of you understands chinese ;-)) anyway - thanks for all your help - Ill figure it out - hopefully