Best 18650 cell for 3p 18A max

izeman

izeman

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I haven't seen any battery recommendation thread for a while, and I now need to build a new battery for a little TSDZ2 mid drive.
This really is a small motor that can do 10A sustained and 18A peak for a short period,
The battery will fit into a saddle bag and will be 14s3p. So every cell will see 3.3/6A.
I have worked with 25R, 30Q, 29E, 35E cells, and know Samsung cell quite well. But the other brands are unknown land. And I sorted those cells Samsungs cells in order of best to worse when it comes to ebike use - of course depending on power demand. And the demand was much higher for my other bikes.
For this small current I guess the 30Q would be fine, but also the LG HG2L sound great with 2800mAh and 20A, or any of the Sony VCT6 with 3000mAh and even 30A maybe?
What cell would you choose in regards of power/life/price ratio and why?
 
Why limit yourself to 3P unless the space available is really tight.
More cells in parallel increases cell life dramatically.
(typo corrected)
 
also, just so you both know, 3s means three cells in series.

pretty sure you both mean 3p, which means three cells in parallel.

recommend editing your title to match what i put in the title of this post.
 
Among the high-capacity cells, I have been hearing good things about the LG-Chem MJ1 cell...but, I don't know what they are selling for these days.
 
spinningmagnets said:
Among the high-capacity cells, I have been hearing good things about the LG-Chem MJ1 cell...but, I don't know what they are selling for these days.
Click to expand...
The MJ1 are 3.500mAh cells and can only do 10A. That's a bit to close to what i ask from them. I don't want them to be 80C hot.
 
izeman said:
This really is a small motor that can do 10A sustained and 18A peak for a short period,
The battery will fit into a saddle bag and will be 14s3p. So every cell will see 3.3/6A.
What cell would you choose in regards of power/life/price ratio and why?
Click to expand...
Samsung 25R ... for power, life, price ... $3.25 x 42 = $137 (IMR). Cycle life has too many variables ... e.g. TLC vs abuse, the quality of your BMS ($30 vs $100), how often you charge to 4.05v vs 4.2v, how much and how often you discharge your pack (e.g. 3.0v vs 3.5v), etc, etc.

As you are well aware the cycle life longevity of the cells in your DIY 14S3P battery pack depends more on U than what new brand name cells best meet your requirements, whether its a $3.25 cell or a $4.99 cell.

Actually, i favor the 30Q (low DCIR for cycle life longevity), but it costs more ... $4.35 x 42 = $183 (IMR). Also, the 30Q is actually good for short bursts up to 20 amps even though it's rated at 15A. 30Qs 3000mAh rating is true; whereas 25R at best is only 2500mAh.
 
30Q has actually bad cycle life.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=103092&p=1517813&sid=2b8a066d606a76c2596e4b922be803c2#p1517372

https://endless-sphere.com/forums/viewtopic.php?f=14&t=97844&p=1435146#p1433642
 
brone said:
If Pajda is right the cheap M29 can do 3C at 100DOD for 1k cycles
Click to expand...
Who/what is Pajda? And with M29 you mean the LG 2850mAh cell? That's a 10A cell as well as I know.
LG seems to have a good life reputation it seems, so I may go with the MJ1 which is 3500mAh and a 10A cell as well. I hope voltage say will not be too massive. I hate it when the "fuel gauge" goes down 30% every time you "hit the throttle" ;)
 
If I were to go for high C-rate cells I would go with the cheapest ones, because most of them are likely to last only 500 cycles.
 
Honk said:
30Q has actually bad cycle life.
Click to expand...
docware is just beginning his cycle tests so have to wait and see how it progresses. FWIW, 30Q has the lowest DCIR of the several cells he is cycle testing ...
https://endless-sphere.com/forums/download/file.php?id=264006

As far as Pajda's post ... https://endless-sphere.com/forums/viewtopic.php?f=14&t=97844&p=1435146#p1433642 ... it's probably based as much on 30Qs use for vaping as for power tools which is not the most reliable indicator when it comes to 30Qs use in a DIY ebike pack. As i said before there are too many factors for Pajda to make such a conclusion (based more on vaping and power tools) without any actual 30Q ebiking experience himself. Doubt that Pajda has any such DIY ebiking proof on the current 30Q 141 cells.
izeman said:
This really is a small motor that can do 10A sustained and 18A peak for a short period,
The battery will fit into a saddle bag and will be 14s3p. So every cell will see 3.3/6A.
I have worked with 25R, 30Q, 29E, 35E cells, and know Samsung cell quite well.
Click to expand...
Of the 25R, 30Q, 29E and 35E which do you favor for your application?
If not 25R for power, life and price ... $3.25 x 42 = $137 (IMR) then which other one do you consider a better buy for price, power and cycle life longevity?
 
Yes, LG HG2 may be the proper cell, but be aware of the many fake HG2 cells. Advantage of such small battery pack is lower weight and size, disadvantage rather shorter lifetime.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=101779&p=1488141#p1488141



LG MJ1 DCIR.jpg
 
Maybe LG HG2L can be alternative .....

https://endless-sphere.com/forums/viewtopic.php?f=14&t=103161&p=1508960#p1508960
 
6A per cell is pretty much in the middle because both, high C or high mAh cells, will give you similar range.
The high mAh cells have more V sag, but make up for it with more mAh, while the high current cells have more V and lower mAh, so usable Wh will be quite similar.

What would speak for high C cells is that you could charge them quicker (those high mAh cells all do not like to be charged with more than 1A), and in cold conditions you will like that they do not sag that much.

Honk said:
30Q has actually bad cycle life.
Click to expand...

Unfortunately i had to find out that batteries where i used 30Q did drift apart after just 100 cylces (with 4.20V cut off, but still quite dissapointing).

I would take HG2 or Sony VTC6.
 
Now that I rethought it, I took a look at my other pack of 30Q cells, which is a 15s10p pack, and this one sees 70A max. So very similar to the per cell current of the planned pack.
As the HG2 cell is not available at the moment I think I'll go for the VTC6 cell 3.000mAh for 3.95€. That way the whole pack will only be 9Ah and 48V, but this still is a much as most regular ebike have (~440Wh).
Only disadvantage I see is, that it seems to have an even lower cycle count than the 30Q, and much worse then the HG2.
 
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