This is way more complex than I expected… I’m gonna use your guys design for the circuit. I’ll send a picture of the final board.
Thank you so much for these designs. This is what I am going to use, assuming all is good and nothing blows up…
Brown represents enclosure, note it is not the correct shape, but what is sticking out will be sticking out. For the exposed wires, I will have rubber covers on them while the port isn’t in use.
you can’t make a parallel balancer cable when the batteries are getting used in a series configuration later. Also there is no need for the switch since you have a loop key.
If he removed the switch, wouldn’t the batteries effectively be connected in series via the VESC?
he should get rid of the switch and put the VESC behind the loop key. I was anyway urging him to change his layout since the balancer cables will not work like this. But it seems to me that the fundamental understanding of how electricity works is lacking in this thread. I will probably stop commenting since it seems to be an endless back and forth with the same mistakes over and over again.
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Agreed. Further, this most recent configuration is dangerous because if he forgot to turn off the switch before charging, the batteries would still be connected in series (as I said, via the VESC).
I think @Kaly did what @Esrapp21 is trying to do. The magic is in the DPDT witch. He documented it nicely here.
thanks for the link - that looks really clean. I would just be worried about the currents going through the small DPDT switch. they are usually only rated at like 2-6A - not the 20-50A we typically use. But maybe @Kaly can comment on his experience and prove me wrong.
Hello guys The switch works really well. It is rated for 20A @ 125V or 10A @ 250V this translate to 2500W and that is more than enough for our application.
The switch need to be use with extreme care when choosing a setting because if the balance leads are connected in PARALLEL while the switch is set to SERIES you are going to BURN 
the balances leads.
To avoid this You’ll need to first choose the parallel position, then connect the charger and then connect the balance lead in parallel.
As a precaution all the positions of the switch have to be label and a warning label need to be paste to the charging port and balance leads, to remind you to check the correct settings.
If you are not sure you can follow the procedure do not do this, it’s easy to make a mistake with the balance leads.
Good luck.
Yeah, while I admire the convenience in use and slickness of your setup, @Kaly, that my setup is idiot-proof good for my peace of mind.
It is exactly what I want to do. I’m going to use that for the project. Thank you for helping, as I am not the smartest with Circuits, as you can tell… @Kaly I get that is is good from a watt perspective, but are there any switches that can take like 50A?
What really matters is the watts, the switch can take 2500W this is really a lot of power for eSk8 application and besides the thing just cost $4.00 plus have a small foot print. 
Ok, thanks!
@Kaly one more thing. It’s probably a stupid question, but I noticed on your project you had two balance ports for 2 batteries that were wired together. When charging the board, how does that work? What do you plug into the charger? Just one of the balance cables or is there an adapter to connect to both?
You need to make a parallel adapter for the balance leads, you do this by soldering tougher balance lead extension. I’ll post a pic in a couple of min.
i am also planning on using this system on my build, @Kaly Your DPDT switch is the missing part for me but now i guess its all clear , i learned alot from this discussion , i also made a diagram of how the set up will be with the DPDT switch maybe it will make things clear for others as well , because your instructable tutorial uses motors instead of batteries i got a bit confused so can you please confirm if this is correct ,
This diagram is correct
Just to clarify the balance leads only will be connected in parallel when charging. In any other state or configuration have to be disconnected.
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Bottom line, The only way to run multiple Lipos in series and charge them conveniently is to use an onboard BMS and a laptop charger. Then you will not have to disconnect and reconnect anything. You won’t even have to open the enclosure. You just plug in the charger and wait. The bms will monitor each cell individually and stop when each cell is fully charged. and you won’t have to charge in parallel, which btw is not really recommended for Lipos. Check out my Lipo with bms build.
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For sure this the most safe way to charge.
I have the same layout as you, @AbdeTy here it is:
I was wondering if this was a good setup and if the battery voltage checkers were setup correctly. (They are the black boxes with the red volt inside)
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