Charge-Only BMS Using 2 Power Supplies in Series, double check my plan?

Build, Repair & Mod
#1

I purchased two of these power supplies and plan to wire them in series according to the diagram below in a charge only configuration for my 14s battery build.

bmswiring

14sbms
14sbms480×640 153 KB

psus
psus480×640 156 KB

I realize that the lack of ground on the second PSU will require strong isolation between PSUs. (I’ve seen this done before)

The BMS has a spec sheet that makes it seem like it will deliver a constant charge current of 15 amps. The power supplies are rated for 16amps.

image

I just want to double check that this means the BMS will maintain a constant current, because the PSUs are not constant current supplies. (As opposed to a BMS that will shutdown when the charge current exceeds 15A).

#2

Make sure earth and gnd are separated on the “upper” PSU to aboid shorting the + of the “lower” one to gnd.

#3

Yes. Agreed. I certainly will take precaution to avoid that shorting risk. Thanks!.

#4

bms will “only” charge to 15 even if the psu is rated higher (normally)

one question : never did that but you really need to wire the earth to the - on the bottom psu ? always though that 1 earth connecting was enough…

#5

I am told that it prevents the person from feeling a shock (AC leak) if they touch the negative lead of the battery (which might be chassis ground for the ESC box).

See here for further explanation: This is why I was shocked by my 3D Printer IMPORTANT FOLLOWUP - YouTube