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

It wasn’t that they were discharged at the end of the ride, but everytime I accelerated they would sag 5v and put my board into limp mode.

I am surprised it draws that much.
At which SOC does the sag become an issue?
If you limit the draw at lower SOC, does that mitigate the sagging?

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I don’t have any kind of meter on my board as I wasn’t told how to get older firmware until after I had flashed all my VESCs, and the Bluetooth adapter I have is no longer supported.

So I need to reflash them to older firmware or get a supported Bluetooth adapter then I could tell ya.

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Same experience as you. I use them in a 2p setup. Pulling 180amp, give a lot of voltage drop, minimum 10v. That takes down some top speed (I use them on my diy electric gokart)
They hold most of the charge between 3,6v and 3,2v, again this take down topspeed and watt. Thats why i´m building a new battery out of molicel p42a at the moment. Looking forward do to a comparison between these two. At the moment my topspeed is 104km/4… pretty sure I can hit at least 110km/h with Molicels, but time will tell.

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12s4p or bigger? No room in the kart for another P group of pouches?

There internal resistance is to high to be anywhere near what the spec claimed but I was exspecting it to be more of a 50amp discharge think of a 3p pack that’s 9Ah at 60amp discharge and take up less space

12s 8p fits in that hummy deck that’s a 24Ah 180a discharge and still got room for ESC or BMS

There over sized over specked pore performing cells that are cheep only use I see is for huge cheep packs

Nope, no more space

A 20s6p or 22s6p battery with the NESE system

A 20s6p out of Molicels, take less space vs. my current 20s2p pouch battery. And gives me 54% more capacity at the same time :call_me_hand:

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Did you figure out how to flash older FW? I need to do the same as one of my duals boot loaders is corrupted and stuck on older FW while the other is running new FW. So I need to downgrade the good side now :joy:

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Yeah I learned you need old vesc tools. There is a thread on there somewhere where you can find old vesc tools.

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Oh, that explains. I also just read the newest VESC tool now supports older FW. Ackmaniac does not seem to do so though, yet.

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I guess you gotta keep in mind that due to the power density of these cells they aren’t suited to our space constrained vehicles. Where they really shine is in larger stuff such as electric cars and bikes. These cells were pulled from Chinese electric buses so that is obviously a good use case as they can fit so many of the cells and get the power required to move a bus

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True suppose it’s down to picking 2 out of 3

Cheap per AH
Max Discharge Per AH
Power density

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think it can be simplified to pick one of these two
like how 40T has 30a output, but “only” 3000mah capacity for a 21700
but 35E has 15a output, but 3500mah for a 18650 cell

the chemistry itself dictates what type of battery it is

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I think a 12S2P will fit really nicely in an Apache 2800 Case.

the sides have to be bent down and you need some thinner foam.
Upon closer inspection I think 12S3P might work also.

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Is bending those sides an issue at all? They extend out quite a bit and honestly just get in the way

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Jehu bent them in his video :man_shrugging:

I would be more cautious about bending the tabs because the cell casing is conductive.

Definitely wouldn’t bend the top or bottom but knowing that space can be saved is good. I’d love to figure out a way to water cool these cells for far longer life

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most of the conductivity will be between faces, just due to the surface area, but if you bend the sides, it looks like you could sandwich them between two watercooling blocks on top and bottom (and another pair on the faces). I would be careful have the plates on some sort of elastomer so you don’t over constrain them from thermal expansion though.
edit:
While the heat transfer through the cell bulk is better than through the faces, the heat transfer from the cell to the cooling block on its edge will be limited due to the imperfect contact caused by the folded/overlapped/seamed edges, so some study would have to be done to verify efficacy.

would it be easier to flood the seahorse/pelican/apache case with mineral oil, add inlet and outlet ports to the case, then use an external pump to recirculate the oil through a radiator @kalebludlow?

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Added this cell to the master cell comparison sheet

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