200A discharge 3.7V 8AH flat pouch lithium ion cells

#41

so what chemistry are they? high discharge, 4.2 top voltage, low energy density, 2000 cycles.

#42

You can tune NMC chemistry to deliver about anything you want, with the usual tradeoffs. You can favor capacity, or cycle life, or discharge, orā€¦

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#43

I wonder if we can get a 350 cycle high density high discharge NMC! =D (approx a full charge every day for a year)

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#44

That would be Molicel P42A for example. 4200mah, up to 45A and according to datasheet still 85% after 500 cycles. According to specs and everything I read about it, this is one of the best cells available (although it would be more realistic to assume 4000mah and 30A).

Also as a general note: cycle life according to datasheet is almost always measured by discharging from 4.20v to 2.5v, so it is the worst case in that sense (although not worst case in terms of discharge). So cycle life will be a bit better in reality if you donā€™t discharge that deeply.
This doesnā€™t help the 30Q thought, as it is rated for only 250 cycles (to 70%). So the 500 I mentioned earlier are almost too optimistic.

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#45

Ahh, thatā€™d explain the high density and high discharge capabilities of that cell

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#46

slot-cars-1
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:flushed:

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#47

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Here we go Mario!

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#48

Did cross a milestone with the spim08hp on my electric gokart yesterday
Looking forward to test Molicel p42a though

Screenshot_20200227-185148
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#49

Got a pelican case on OfferUp for $20! Any larger and it wouldnā€™t be mountable.

20200227_103546
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Look at that fit though

Should fit a 12S2P12S4P ish

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#50

20200227_124151
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too large for this kids deck, (built in heel straps?)

Might fit on a larger MTB. Iā€™m hoping the battery could be swapped between go karts and drift trikes and whatever. Iā€™m also considering having it be 4 individual 12S1P packs so they can be further split. It can actually easily fit 12 cells stacked.

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#51

I also plan on doing single parallel groups for these cells when I get some, I feel its the best way to stack them without having this big massive pack that is impossible to work with. How do you plan on connecting everything? Anyone else that has used these cells Iā€™d love to see your solutions too

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#52

the tabs have two slots in them for two bolts. I also like the nickel plated copper foil spot welded @Arzamenable? I think did

#53

Screws have no issue with the high amperage that these put out? Iā€™ve just never seen any numbers for screws so not sure if I need to get something specific

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#54

The screws are just to hold the copper or aluminum bus bars/wire you are using tight to the aluminum tab. Hopefully they donā€™t actually pass current I think

#55

Definitely was curious about wiring as well as I have zero experience building batteries, especially something larger like this so want to make sure I donā€™t make stuff melt or explode

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#56

haha someone help us :pleading_face:

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#57

I didnā€™t spot weld. I used foil clamps.
https://www.te.com/usa-en/product-329656.html

Did you get them to weld?

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#58

Oooh never seen these dealies before. I was imagining a binder clip lol

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#59

Haha, negatron. I hammered on 2 double wide foil connectors per series connection. Thatā€™s shits going nowhere.
image

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#60

Idk if itā€™s the material on the tabs or the sheer dissipative power of the form factor, but Iā€™ve found it impossible to solder or spot weld the tabs.

These cells are great for high power racing go karts and the like, but are too big for ESK8 and are cutting it close on EMTB.

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