A solution: Discharging using e-switch with always-on charging

There has been discussion on the ideal setup where a BMS with an e-switch is used for discharging (turning on the board), BUT also where that same BMS supports charging the battery without turning on the board/switch.

It seems obvious, yet according to SuPower, such a configuration is not possible:

That sucks, because who wants to have to turn on their ESC just to charge?!

Well, I believe I have figured out a solution using TWO BMS’s:

Please observe the diagram below. Would this work?


Enertion’s space cell bms does exactly this somehow, not really sure how it works.

I personally bypass bms discharging to avoid this issue.

In this case, the discharging BMS essentially functions as a big anti-spark switch (edit: with OC protection h/t @SilentException). So @Jinra, if you’re bypassing the BMS discharging, I’m guessing you’re using a vedder or anti-spark switch?

why use a BMS for discharge at all then? Use a Vedder Switch to turn on your board if you want an “e-switch”.

Yep I use an anti spark switch

why use a BMS for discharge at all then? Use a Vedder Switch to turn on your board if you want an “e-switch”.

@Maxid Cost. Vedder switches cost upwards of $40-60 plus shipping, and you need buy a BMS. With the two-BMS setup, the cost for both together is under <$55.

Example: 60A Discharging BMS ($39 shipped) and charging BMS ($15 shipped)

Output BMS also serves as LV and OC cut-off, not just glorified anti-spark switch :wink:

I’m talking about configuration from OP, and that should work just fine for the purpose. Would be a bit careful using cheap BMS even if just for charging. Balancing cells is an art :slight_smile:

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Where are you buying your Vedder switches? Esk8 sells them for like 25€. Also the Vedder needs less space than two huge BMS

I’m been charging with dual Vescs on for months on 2 builds and it has caused no issues at all. I feel its well worth it to have all the protection a BMS affords in discharge mode along with a dependable and convenient anti-spark solution. I tried stand alone e-switches and they failed. The e-switches in my Bestech bms’s have been rock solid.

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@Namasaki Ah, can you clarify your setup? Dual Bestech BMSs like the setup described in the original post? Or are you using Bestech BMS + vedder/anti-spark switch?


Just Bestech Bms with dual Vescs on 2 separate builds. That is, I have 2 builds that have same setup.