13s4p/48V/21700 DIY Questions - Samsung 50E okay for 750W BBS02? [Edit: Why is nothing in stock?]

[anku94]

I'm rebuilding a battery pack for my ebike. It's a 750W hub motor, and typically cruise at 300-400W, occasionally using 700-800W to overtake/accelerate.

My current battery is from Luna - it's a 13s4p 18650 48V battery with Panasonic GA cells (10A).

I'm DIYing a replacement and looks like 21700 is the way to go now. Availability-wise, I can't find much except Samsung 50E and Molicel 42A (in the US). Is 50E a reasonable cell for my usecase? My math suggests that I'm mostly drawing 1-2A (200-400W), occasionally hitting 5A and never really beyond. The 5000 mAh is also nice to have over the 42A. Thoughts?

Thanks!

EDIT: It seems that that isn't in stock either. The only 21700 cell around $5 that seems to be in stock is the 42A - anyone knows what's going on?

 

[TDA78]

The 50E is perfect for this use case. I pull peaks of 7.5A from the 50E in an e-bike (30A @ 4P) and they don't even get warm. The cells go in and out of stock all the time. At least you know you are getting fresh ones!

 

[anku94]

The 50E is perfect for this use case. I pull peaks of 7.5A from the 50E in an e-bike (30A @ 4P) and they don't even get warm. The cells go in and out of stock all the time. At least you know you are getting fresh ones!

Thanks! I ended up getting a UnitPackPower pack instead. Really wanted an excuse to get my own spot welding gear and everything but there's a sale on AliExpress and I got a 20Ah 48V LG 21700 battery for $290 and it was too good a deal to pass.

 

[Dak77]

Thanks! I ended up getting a UnitPackPower pack instead. Really wanted an excuse to get my own spot welding gear and everything but there's a sale on AliExpress and I got a 20Ah 48V LG 21700 battery for $290 and it was too good a deal to pass.

That's a suspiciously good price. Are those verified to be authentic cells?

 

[amberwolf]

That's a suspiciously good price. Are those verified to be authentic cells?

It's UPP.... :/

 

[anku94]

That's a suspiciously good price. Are those verified to be authentic cells?

I got it during some AliExpress sale days with a coupon code that gave me $40 or so off the list price.

Tried taking the case off to take a look at the cells, but it seems to be fairly well packed with everything glued together and kapton tape and barley paper everywhere including cell terminals, and decided it'd be too much work to get through.

I tried doing my homework and tbh I didn't find any credible complaints against UPP, so went for it.

 

[anku94]

That's a suspiciously good price. Are those verified to be authentic cells?

Finally got around to taking it apart, and seems to have LG M48 cells. The only datasheet I could find suggests that they can't do a lot of current, but should be fine in the ~2A regime I run them in. Build quality and all seems to be good too from what I can see. Great value for $$.