E-switch on BMS

ESK8 Electronics
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Hi guys, as many of you may know, there’s a group buy going on right now for some batteries in Europe, which is quite a rare thing. Since the manufacturer lets us take a design, and I noticed that many people are asking for a good battery with a bms in a compact form factory, I was wondering if any of you has a diagram (or can make a quick one) for one like this from @denton I would do this by myself but I know nothing about batteries :smile: Thank you very much :slight_smile:

THIS IS NOW A DISCUSSION ABOUT PUTTING A MOSFET E-SWITCH ON THE BMS

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Here is the website I picked up my BMS from http://www.batterysupports.com/lion-lipo-nbsp-36v-nbsp-10s-c-32_41.html They have this wiring Diagram that I followed for this battery. I would recommend one of the BMS that have a built in power switch.

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Just FYI batterysupports can actually add an e-switch for you on their BMS’s

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Are you sure? @fedestanco has a group buy with e-switchs on the bms

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Yes, but you have to reach out to Lilian directly to have her add the e-switch to the BMS.

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I don’t think the bms in the group buy is from batterysupports, so at the moment that’s not a priority, I think. E-switches are cool though, hope it will be possible to have one :wink:

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DANGIT! If I would have known that I would have had it done… Well… You live and learn I guess. That would have saved me a lot of trouble.

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The bms itself is an e-switch: it can turn off the battery for several reasons: voltage errors/ amp errors/ temperature threshold… When it comes to add a physical button the options are 2:

  1. there is a spot on the bms board designated to add one on-off switch (like the bms on my thread)

2)You make the bms think something is going wrong: for example you can short the temperature switch/ fake a failure in one of the balancing wires/…

All the options mentioned work in the same way since the reaction in the board is simply the activation of the mosfets.

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So you’re the one who adds the switch in your GB?

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Yes, I asked the manufacturer to leave the soldering spots (for the switch) free, so that I can solder an on off switch with a better design (the original was red and rectangular).

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Is there a place where I can actually do that on the board I already have?

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woah, really? I traied earlier this year and she just kept sending me to a different product.

Can i get my usual 12S 60Amp favorite with an integrated eswitch?

oh Lillian…

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the 2 spots in the circle should be designated for e-switch/temperature switch. If you could provide me with hi-res pictures I could confirm what I am saying.

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I will later, thank you!

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WHAT IS THIS UNDOCUMENTED MADNESS.

So If I short that the BMS will power down?

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So Lilian told me you connect the switch like this,

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However, she said the BMS would have to be modified first before you can do this.

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Here’s some of the email thread

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I will try to explain: When it comes to print a circut, although the bms company has several models of the same bms (the standard, the fancy one with an e-switch…), they manufacture just 1 type of printed board; all the fancy add ons will be added later.

These 2 spots (see pic) could have served 2 functions: 1)temperature switch 2) e switch ACCORDING TO THE ONE (function) THEY PICKED, YOU HAVE TO OPERATE IN 2 DIFFERENT WAYS TO ADD YOUR E SWITCH

1)spots designated for temperature switch: IN THE NORMAL CONDITION, current DOES flow through the temperature switch. TO GET THE BMS IN “ALARM MODE” (to turn off the battery) you will need to OPEN THE CIRCUIT: remove the resistance next to the spots (see pic).

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2)If the spots are meant to be for an e-switch, it couldn’t be easier: just short them to turn off the battery.

I hope this will help you build better packs.

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Could this be tested with a BMS that is not 100% functional. Because someone should with extra BMS’s from prior builds or with a burnt out component should give this a try and let us know because this is a game changer.

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When this change is made, does the BMS switch have to be on to charge the battery?