How many people use 26650's?

[amberwolf]

I can't imagine wanting to use a cell that gets hot under the load I'd be putting on it every day in a battery pack.

If a cell generates that kind of heat on it's own, standalone, how hot would it get inside a pack?

I know some cells are probably spec'd to operate at higher environmental temperatures, but if they're actually generating those temperatures themselves, and they are in the middle of a pack, the heat of that pack inside is going to increase significantly beyond what one cell's heat is, because all those watts of waste heat are being confined inside the core of the pack--only the outer layer of cells have much surface area to dissipate the heat they themselves generate, and in addition to try to get rid of the heat they're absorbing from the pack's core. Only the ends of the cells in anything but the outer layer can radiate heat out of the pack directly.


How much of a problem any of this is, I don't know.

But heat is in general bad for batteries, accelerating aging and such, aside from the possibility of thermal runaway if core cells cant' shed enough heat and loading keeps making more.

 

[flat tire]

When will people learn...name brand cells aren't even that much compared to the rest of a decent ebike build.

"The Bitterness of Poor Quality Remains Long After the Sweetness of Low Price is Forgotten"

 

[Hillhater]

There are several 26650 cells available that have been tested .
For example..
http://lygte-info.dk/review/batteries2012/AWT%20IMR26650%205200mAh%20(Red)%202015%20UK.html
And
http://lygte-info.dk/review/batteries2012/Ebat%2026650%205000mAh%20E7-26P50%20(Black)%20UK.html
And the Efest 5ah
http://lygte-info.dk/review/batteries2012/Efest%20IMR26650%205000mAh%20(Purple)%202017%20UK.html

 

[Hillhater]

When will people learn...name brand cells aren't even that much compared to the rest of a decent ebike build.

"The Bitterness of Poor Quality Remains Long After the Sweetness of Low Price is Forgotten"

You have to be careful relying on brand names alone to ensure quality.
There are a lot of Mercedes buyers around that will verify that !
..(and VW )

 

[spinningmagnets]

"The Bitterness of Poor Quality Remains Long After the Sweetness of Low Price is Forgotten"

Ha ha! Yeah...I have heard that quote from other ES members before (you know who you are!). I agree. Consumer psychology is a fascinating subject. Buying something at 0.99 cents is "a thing", instead of paying a dollar...my kit "X" is cheaper by $10, but..after you have entered all your information into the purchase page, only to find out at then end that the shipping is $10 more?...we keep seeing this because...it keeps working.

"I have seen the enemy, at it is us" -Pogo

 

[Garen]

I noticed a couple guys on youtube are gearing up to use LiitoKala 26650-50 batteries:

https://www.youtube.com/watch?v=21HCajp1ecM
https://www.youtube.com/watch?v=EEHPeidNqws

AliExpress listing here:
https://www.aliexpress.com/item/10PCS-LiitoKala-26650-50A-5000mah-26650-Li-ion-3-7v-Rechargeable-Battery-for-Flashlight-20A/32791838898.html

Only test results I could find were here:
https://lygte-info.dk/review/batteries2012/LiitoKala%20INR26650-50A%205000mAh%20(Black)%20UK.html

Most reviews I could find seem to be for flashlights, e-cigarettes, and vaping. Couldn't find anyone that had built a large pack for a much larger application like an e-bike, so curious to see how things turn out.

 

[markz]

There is a good reason why Elon Musk went with 18650, perhaps its energy density.

 

[Hillhater]

There are many reasons why Tesla went with 18650's,..
(And those decisions pre-dates Musks involvement in Tesla)
One of the primary reasons was safety of small metal cased cells, and another was the ready surplus of 18650 availability due to the winding down of laptop demand which had created huge manufacturing capacity of 18650s.

 

[Punx0r]

Skinnier cells shed heat better. Note Tesla went to a larger cell than 18650 but smaller than 26650.