Help choosing the best 21700 cells for my build

[Boanz]

Hello all new member and new to ebikes.i just started getting into ebike building about 3 months ago.ive done quite a bit of research and learning in past 3 months I feel like my head is going to pop lol.only item i have left for my build is choosing the cells for my battery so amorge can build it.i originally was going to go with the molicel p50b but after looking into them it seems they arent much better then the 45s and they run hotter.this is based on vids and other sources on the net.like I said im new and still learning.can you more experienced builders recommend a good cell for my builds needs plz.for my build im using a qs205 50h 4t v3 paired with a 96680 fardriver i plan on cruising at 35-50mph depending where im riding and hitting 70mph peak here and there when needed.ty in advance for any help these are my choices for 72v and 96v battery

 

[docw009]

Choice is between 20S-12P or 26S9P? My opinion is that if you want the cells to run cooler, you pick 12P, but if you need to run over 50 mph then it's 26S. Got room for a 26S-12P?

 

[Boanz]

Choice is between 20S-12P or 26S9P? My opinion is that if you want the cells to run cooler, you pick 12P, but if you need to run over 50 mph then it's 26S. Got room for a 26S-12P?

Im guessing there isn't room for that.i gave amorge all the measurements and those are the 2 options i was given.i was going to go with the moli p50b but saw a few comparisons with the eve and p45 along with a few other cells and they seem to run a bit hotter then other cells.like I said Im new and looking for some opinions on what cells may be best for my intended use.now im thinking maybe the eve or p45 any suggestions would be great help ty

 

[mrmojorising]

Rs50, tenpower 50xg and Eve50pl are all newer, better cells with tab-less tech, meaning they have lower resistance and thus produce less heat.

The molicels that Amorge have are possibly old stock as molicel had some production issues within the past two years, and they are also older cell models

A good overview/place to start is Mooch's cell test data: https://www.patreon.com/posts/18650-21700-e-138053835

 

[sternwake]

TenPower 50XG are the coolest running 5.0ah 21700 cell available at this date, as far as I know.

I see no reason to step sideways or down to any cell of less than 5.0ah nominal capacity, unless price is the prime consideration.

A key word is 'Nominal' capacity. It is measured at 0.2C, or just 1 amp for a 5.0Ah cell, whether that is a power cell like the Reliance RS50 or an energy cell like the Samsung 50G.

Actual delivered capacity at the given load is often far far different, and where testers like Mooch and Pajda do us all a huge favor.

Trying to make a cell choice based on Nominal ratings is unwise

On your list of options the only ones I would consider are the RS50 or 50XG, and if you can wait a few more months then the RS60 and the 60XG could be available by then. Perhaps even the fabled Molicel P60C.

Mooch has recently posted some very interesting results from the RS60 samples Reliance sent him.

 

[docw009]

Cell datasheets will show capacity at higher drain currents. Here's the P50B. In real world use, the BMS will cut off at 3V/cell.

re's the P50B.

 

[Boanz]

TenPower 50XG are the coolest running 5.0ah 21700 cell available at this date, as far as I know.

I see no reason to step sideways or down to any cell of less than 5.0ah nominal capacity, unless price is the prime consideration.

A key word is 'Nominal' capacity. It is measured at 0.2C, or just 1 amp for a 5.0Ah cell, whether that is a power cell like the Reliance RS50 or an energy cell like the Samsung 50G.

Actual delivered capacity at the given load is often far far different, and where testers like Mooch and Pajda do us all a huge favor.

Trying to make a cell choice based on Nominal ratings is unwise

On your list of options the only ones I would consider are the RS50 or 50XG, and if you can wait a few more months then the RS60 and the 60XG could be available by then. Perhaps even the fabled Molicel P60C.

Mooch has recently posted some very interesting results from the RS60 samples Reliance sent hi

 

[Boanz]

Ty sternwake for the suggestion and Ty all for the help much appreciated

 

[BlueSwordM]

RS50, not even close these days.

The RS50 is the only cell with any sense of price stability regarding supply

It's also the toughest cell out of all the ones we currently have.

 

[CRF265]

Choice is between 20S-12P or 26S9P? My opinion is that if you want the cells to run cooler, you pick 12P, but if you need to run over 50 mph then it's 26S. Got room for a 26S-12P?

Provided the total number of cells is the same, for the same power the individual cells will draw the same current regardless of the pack configuration. The configs above have almost the same cells so there is minor difference. 240vs234 cells

Ie For a 20kw load, the 20s12p will require 278 line amps, which is 23.2 amps per cells
For 26s9, it only requires 214 line amps which is 23.7 amps as the load is shared over 6 less cells in total.

Advantage of higher voltage is the battery wires see less current and the motors rated speed increases. For same price and same packaging running 96v over 72v is a no brainer

 

[Boanz]

Ty all for the advice sry ive been busy and was waiting on some answers from amorge i believe im going with the 96v with eve 50pl or rs50 im leaning towards the eve 50pl for the amps and price if someone has any other advice plz help ty all again for the help so far is still have alot im learning and alot more to learn

 

[Boanz]

BTW I did ask about the tenpower 50xg but they are not available at this time kinda bummed