Recent content by dukestar

john61ct, based on your quote the 50E may be a good option for you but note the datasheet has a recommended charge current of 2.45A for pack longevity, max 4.9A (not for cycle life). If you need a fast charge it may not be the cell for you. HTH

Pajda, thanks for your input much appreciated. Your comments about pack temps is reassuring. Do you think if I max the pack temp at around 40°C - 45°C that I will be ok with regards to preventing pack cycle life degradation due to excessive heat? I think I can manage that without active cooling...

Ok, so after going back and forth between 40T and 50E I built my battery with the 50E because of the cycle life rating of >80% after 500 cycles. The 40T had same rating as 30Q which is what my current pack used. Here's the build details. 20s7p - due to space constraints I hot glued 16s7p on...

Hello, got a question on nickel strips...based on the ampacity chart a .15mm 8mm wide strip can handle ~5A...if I use a single wide strip of .15mm nickel along the entire length of p cells instead of 8mm strip to connect in series how do I calculate the max A the series connection can handle...

Thanks @pajda...any input on the Lishen cell I mentioned?

Came across this cell: Lishen LR2170SF 13.5A 4500mAh 21700. Does anyone have any comments on them? Looks like a possible compromise between the 40T and 50E. Haven't seen much on Lishen cells so not sure if they are legit or not.

@pajda On a typical ride I use say 15A in 60min so I average is 15Ah or around .25C if using 50E in a 7p config. However I'll have hill climbs where I pull 50A for say 1 minute or around 1.5C. Do you think the 50E could handle this?

I hooked up with Pat at Sportsman Flyer (https://sportsmanflyer.com/) and worked with him to put together an electric version of the gas repros he makes. The ebikes aren't on his website but are available if you reach out to him. He has tons of pics on his Flickr here...

No wheelies...but lots of fun... https://imgur.com/a/tgNsEv0 https://imgur.com/a/YrS2aCj <-- MPH!

@icherouveim and @matador thanks for the replies...looks like I'll build a 20s7p 40T pack...50E off the table. I'm starting to gather the parts to build it. I got a JP spot welder, BMS, nickel strip, shrink wrap, glue gun etc, just need the cells now. Will post my results when done. Probably...

@icherouveim, do you know how likely the 40T cycle life will be similar to the 30Q's? I'm not happy with how my 30Q pack lasted. I definitely don't want to build a new pack with cells that have a cycle life profile similar to the 30Q.

Thanks Matador. This was my concern with the 50E, that the max of 9.8A is too low for my application. The 40T looks like the 21700 version that is closest to the 30Q. The issue I have with the 30Q is that I didn't get the cycles I was expecting even though I charged it to 90% most of the time...

Thanks Pajda...I'd say on a typical ride I average ~20A so the 50E may actually be a good choice after all.

Same as current pack 20s7p so 7. So max A would be 68.6. So my max of 65 is imo stressing these cells and hence my concern. Thanks for the link I'll check it out.

I have a 20s7p 30Q pack. Am at 250 cycles since 06/2017. I typically charge to 80.1V (95%). I'd say 90% of the 250 cycles were to 80.1V. I'd typically use around 12Ah per ride. I'd guess I could not get more than 15Ah out of this pack now. I also notice the voltage drop seems to be more severe...