12S-3P Battery module

How-Tos & Esk8 mechanics Esk8 Mechanics
#21

me: Thats a cute little PCB…
OMG THATS MASSIVE!

Great work Ernesto! Looks really professionally made and designed

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#22

@Kaly do you sell the aluminium trays too? What are the dimensions of those?

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#23

Thank you for making such an awesome modular design and for the write-up!

Apart from this concern:

I have a wish that would make this far more valuable for the DIY crowd:
If you designed your current carriers (and maybe the BMS) for 20-30A per cell, it would make it possible to use a 12s3p or 12s6p with sufficient power. I think there is a good reason that Samsung 40T is currently the most favored cell - people like to have power but don’t need or have the funds for a 12p pack.

If you just upgraded the nickel plates to solid ones (as suggested) use 10AWG wire, and bypass the BMS for discharge, this wish would already be addressed.

Great work, keep it up!

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#24

What’s wrong with a 12S6P pack of Sanyo NCR20700B? That’s 120A DC output right there.

I love the idea of cell level fusing. @Kaly probably wants battery pack kits as safe as possible.

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#25

20700b is only 15a continuous

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#26

Not according to BatteryBro! :rofl: 90A DC is still plenty Amp for most.

Hey @Kaly, do the 20700 kits have wiggle room for 21700 cells or no?

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#27

Assuming the cells are true 20A cells, using his kit, you could still only get 10A per cell out of it, for a total of 60A.
That is because his current carriers and BMS are designed for 30A total per 12s3p module.

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#28

So you can’t bypass BMS discharge because the Nickel is too thin?

#29

You can’t bypass it safely.
To me, the nickel looks like it will support 10A per bridge at most.

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#30

that shyyt is Pluto man…bruh you way out there.

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#31

So if I want to bypass the BMS, just upgrade the Nickel?

#32

That’s the main thing, yes, though you should also consider:

  • Use a copper braid or two for the series connection from one side to the other (instead of nickel)
  • potentially: Avoid directing any discharge paths through the PCB (on the positive terminal you should also upgrade the fuse if you use it)
  • use AWG 10 wire to connect the different pack, or use an individual cable for each pack instead of making a bus.
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#33

Kinda feels like these suggestions are going against @Kaly’s design ethos in this instance.

Obviously these were developed to be used in 6P, 9P or 12P config and within safe limits.

I agree with your points if all you want is to push more Amps out of less P groups.

#34

Exactly, that is why I voiced the wish to change the design to accommodate for double the current.

I love the simplicity and modularity of the design, but I don’t see myself and many others using it due to the stringent current limits.

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#35

The 20700b can fit in a different configuration but not with the current pcb design.

The bms can be bypass but why use a safety device and then bypass it :thinking:.

@PrivacyDoctor
The max wire thickness is 12AWG due to space constraints for 10AWG need to use flat braided equivalent here

The nickel tabs can handle safely more current but at a minimum of 90 Amp for total pack output is good for more than 90A output it makes more sense to use Lipo.

To monitor battery output is good to have a watt meter connected to the battery before going into the ESC this will gauge the real power requirements for the battery :slight_smile:

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#36

Because a discharge BMS is a safety device for the battery, not the rider.

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#37

Which 20700 cells do you use then?

#38

Sanyo 20700b

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#39

For this setup i use the Sanyo 18650GA
for the 12S-4P I go with the 20700B

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#40

That’s the page for your 12S3P kit though?

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