BMS Lowers voltage once plugged into VESC

When the vesc is not connected everything is just fine 42V, but when ever its connected it drops instant down to 3.7V.

And everything else seems fine, kinda seems like a dodgy BMS but it charged it up just fine so almost cant be or can it?

As long as the VESC does not have a low resistance on the input wires it is ok to plug in directly to battery.

The BMS may have other problems so if it works without the bms then I would suggest changing it or possibly using for charging only. But be sure to monitor its behavior since at this point it is questionable to rely on ti keeping your batteries safe. Better safe than sorry

Yeah, was also really just the plan.

The battery is only meant for testing anyways so not going to be used on a board but more to tweak my vesc settings since i have no variable bench power supply anymore or one that can do a high enough amount of amps (20+)

But thanks, ill just bypass the black side as well.

It should just charge via the balance leads and the red charge lead connected to the battery just fine right?

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Ah, okay then.

I have the same kind of BMS it seems like (10S 60A from and the charging is done using the red wire from battery directly and the P- port

Mine has a CH- port for charging, should be fine then.

Thanks ill give it a try tomorrow and see how it goes.

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You must leave the b- wire connected to the battery and then run a second wire to the load, if you don’t the bms won’t function

Like this? Thats how i planned to do it, wire a new black wire on the battery that goes directly to the vesc and leave the one connected to the BMS

Dont mind the white stuff and black wire, only the battery to bms part is what im doing.

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Like this

Edit; yep yours is right


That looks correct. The path for black should be from battery to BMS whichever port it uses (refer to diagram of your BMS) and out of the BMS charging port to your charging plug. Red goes straight from battery. Of course balance leads have to be connected too. For discharge, just both red and black directly from battery


Perfect, going to sleep now ill hook it up tomorrow and see how it goes.

Anyone know the amp limit of an Evolve Bamboo GT battery? I read somewhere its max 45Amps only gonna do 20 on it though but just to be safe so i aint blowing stuff up.

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You could try increasing amps until the battery sags a lot then you’ll know your close to the max amps limit

I unfortunately dont, maybe try asking someone who is rebuilding the batteries. Someone is providing it as a service here on the forum, maybe they will be able to tell you more.

So just read voltage on +/- op the amp a little and see if i get huge dips?

Found this on the Evolve Forum:

“Our motors are rated at 3000w, and batteries at 36v. 3000 / 36 = 83 amps”

83amps cant be true can it?

Yeah, do you have a Bluetooth module for the vescs? Otherwise @darkkevind might know

Those amps would be peak not constant

Yep, got a Metr module.

So sounds like it safe to assume the battery can supply around 40amps and 80peak.

Same i read else where

Yeah I would says that’s a pretty safe assumption. I wouldn’t go much more than 20-25a per Vesc

Yep, only using single drive myself so way under the maximum but better safe then sorry.

20amps is what i plan on using the board at for the rest of its life and just using the battery pack i made now to get it up and running so when ever i get the money for a real pack i no longer would have to worry about vesc settings and i can just enjoy it or if im super lucky and get a good offer on the complete without battery the buyer wont have to do anything else either :slight_smile:

Yes. The Evolve BGT, CGT and GTX will pull a max of around 80A peak for a few seconds… It can’t sustain it for any longer. It pulls around 40A continuous though. Even then it will overheat and restrict current if you do that for too long…

Cheap Chinese parts unfortunately. Not even good Chinese parts! :confused:

Sooo it works now flawless and hooolyyy fuuuc my board has a lot of power now.