Thanks for your thoughts guys. I’m pretty sure i’m looking at a 6p or 8p to the range up where I want it to be. Would the 15A discharge of the 30q and vtc6 be a bottleneck with the rest of my components? Or would the P size that I’m looking at still allow enough pack current to keep up?
figuring in the 6p to 8p range. On initial discussion with this builder I had explained that I was quite interested in the 40t’s as I already use them in another board. The cost difference between them and the hg2’s is not much really, I’d gladly spend the money on them. I’m just wondering if there is some logical reason why the 18650 options would serve me better than the 21700 option.
The VTC6 and 30Q both perform better at 20A discharge (in terms of voltage sag) than the “20A” rated HG2. Take a look - A full 100mv difference across pretty much the whole discharge range.
Thank you for this MD, yeah it seems the hg2 wouldnt be as good as choice than the other two, considering the cost is basically the same for me
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Sorry, to clarify I realized I didn’t mention my intended battery was 12s6p to 12s8p
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Check this out
Vaping and esk8 have similar high-drain demands on cells.
If the prices are similar, I think probably 30Q would be the better.
But if you can go for 21700 form factor, the Molicel P42A is a better cell it seems.
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In my opinion, the only two reasons to pick 18650 over 21700 is size and price. If you need the smaller cells to fit in your enclosure, go 18650. If you cant afford a pack that you will be happy with made of 21700’s, then go 18650.
Otherwise, go 21700. Molicel p42a’s are my current favorite for balancing high current and high capacity.
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Less cells - less headache also
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The P42A is pretty much the best out there on paper. For comparisons sake:
- 12S4P P42A = 725 whr 140 A max rated cont discharge (3.2kg)
- 12S6P 30Q = 777 whr 90 A max rate cont discharge (most run 20A each so 120A) (3.3kg)
So for less weight and higher discharge I’m definitely going with the Molicel (within this comparison), that would be my suggestion. The higher discharge is especially applicable in an AT build since consumption and power draw are generally much higher.
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I agree, If you’re running each cell at 20A then the P42A is a much better choice than the 30Q. The 42A’s lower internal resistance means a higher voltage under load which results in greater run time before hitting your low voltage cutoff.
The nominal Wh spec is okay for very, VERY rough calculations or if running at 1C or 2C or so. But once you start pulling a lot of current then you need the actual Wh delivered spec at the power levels you’ll be running at.
A 30Q at 20A delivers about 5Wh down to 3.2V.
A P42A at 20A delivers about 10.7Wh down to 3.2V
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I forgot to mention that at 20A the P42A will run about 10°C cooler than a 30Q down to 3.2V. This can result in greater cycle life for the P42A or give you more flexibility with the pack cooling.
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The additional points regarding operating temperature and accounting for measured Whr at a given discharge is especially helpful!
@Battery_Mooch once again blessing us with his heavenly knowledge 
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to be able to compare we need to consider P42A is 33% more capacity than a 30Q
30Q at 20A 5Wh
P42 at 30A 8.7Wh
Same apples is a P42A at 30A still 10°C
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I’m just supplying data points. Each pack builder needs to do the power/energy density and weight calculations for their particular setup and weigh the results against their size/weight and $$$ budget.
The 30Q is a miserable performer at 30A. For good efficiency I recommend staying under 15A for that cell. It’s not a power cell. It’s best for low discharge rate energy applications.
I don’t have the actual temperature differences but since the P42A is about 9°C cooler at 30A than the 30Q is at 25A I would expect the direct comparison at 30A to result in an even greater temp difference between them.
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The capacity spec is a lot less useful than we might think.
For a 30Q at 25A the delivered capacity down to 3.2V is about 950mAh.
For a P42A at 25A the delivered delivered capacity down to 3.2V is about 2250mAh.
Using the delivered energy, Wh, spec gives us the info we need without ever needing to consider capacity. We can use that spec to determine whether the cell meets or power/energy, size/weight, and $$$ budgets without regard for capacity ratings at nominal current levels.
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I totally agree with that and much appreciate the time and effort you put in to making a accurate detailed repeatable conclusions.
What I’m saying is in a battery pack we would use 33% more 30Q than P42A this will also mean we run the P42A 33% harder.
That’s why I showed you result of Q30@20A vs P42A@30A as in our packs that’s how thay would be used
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Also needs to be considered that this dude is talking about a 6 or 8p pack.
6p 30q is easily good enough for 90A. Would love to see metr logs of anyone here needing any more than 90A continuous.
30q shines for bigger packs. P42A is more suited to smaller packs in my opinion.
That said…
20s8p P42A in the works 
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Trying to work out on my spud deck I got a 10S VTC5A. With a huge DieBieMS in there. if I change that to a 12S to match my other board and (gets rid of the charger confusion) use a Flexi BMS am I better off with 2P P42A or 3P 30Q/VTC5A
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Ahhh…okay. Thanks!
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