10s BMS help - 11 balance leads?

Are you sure you don’t have those swapped?

This is a “discharge” style high-amperage BMS best suited for discharging through. There are pros and cons to both ways. Neither is “better”.

It’s the over current protection, the BMS in this thread has 120A (data sheet of manufacture). So 60A cont. is no problem, the BMS would cut off at 120A +/-10A. If the total battery max of both Vescs is set to 100A together the BMS will never cut off. But of course it would get hot when pulling e.g. 90A continious. So for your 4WD it’s maybe too small.

On a cheap/bad BMS the continious discharge rate is the same as over current protection (that’s why I don’t like Supower BMS). They claim 60A continious but in real life it’s more 30-40A because the BMS cut off at 60A which is a joke IMO.

My 50A Bestech BMS is 10 times bigger than my 40A BMS which I used for charge only. Because the 50A is real and the 40A fake.

When I ordered the Bestech BMS they only had the 50A in stock so they set 110A over current protection. I had a chat with a Bestech engineer where he confirmed that like 80A for 5-10 seconds and 100A for 1-2 seconds is no problem at all, just not continious. On every ride I reach between 60-100A but only a short period of time, never had problems with heat or anything.

As you can see on the diagram on the BMS, it’s charge and discharge on the same port (C-) so it’s 60A charge and discharge. I was confused in the beginning, too but had chats with manufacture who confirmed that only C- gets connected for both charge and discharge. And I have the same BMS in use connected to C- only so I’m sure.


Really appreciate the helpful people that chimed in on this thread. I’m gonna have to get @Namasaki in here to help when I go to wire this BMS with lipos like the one in his famous 10s high power lipo thread.

1 Like

You first need to decide whether you will discharge through the BMS or bypass it and run it charge-only. You cannot know how to wire it until you decide that. There are pros and cons both ways.

The BMS in this photo is best suited to discharge through.

1 Like

I will probably run it for both charge and discharge then


Do you plan to use 5x2s Lipos?

Most likely yes. Need to take some measurements. Either that or 2x 5s

1 Like

Modified the diagram above to your needs for 5x2s.


2x5s would be easier but more bulky.


We need to add fuses on the charge port negative on these diagrams

I just haven’t fired up GIMP yet today

Shouldn’t the charge port be protected against short circuit anyway? I mean in both configurations, charge only and discharge/charge? Or is my brain not working? It’s 3:10am here :laughing:

After this and this I cannot ever recommend not using a $0.67 fuse there

Damn, had to re-read the topics. @Andy87 didn’t use a BMS but @amazingdave did, that’s scary. But I also read about successful shut downs of BMS after shorting the charge port. That’s what I normally would assume.


But a fuse on charge port can’t be wrong.

I actually shorted on of my charge ports once too by accident. It’s an unfused older one. It has a BMS. Melted the end of the pin right off. It’s still jacked-up to plug in to this day. I was drunk at the time, too.

Damn! A charge port should be drunk-proof.

With how many amps do you charge when using 5A fuse? I guess it’s not the best when charging with e.g. 4A because the fuse could get hot (just my theory).

The build I’m working on currently might not have the surface area on the deck for the 5x 2s but I can always add risers to make room for 2x 5s so that’s why I may end up choosing that option. We will see

1 Like

I usually don’t charge at 4A unless I’m out and about and need to charge. At home it’s usually 2A. If there’s 3 other boards charged and ready, no reason to stress the cells. 4A charging is why I would use the 7.5A fuses though

1 Like