Wednesday, March 8, 2017

Batteries for e bikes


samsung 29E




Large lithium-ion cells hold too much heat. You really need smaller capacity 18650 cells like Panasonic NCR18650PF 2900mAh or Samsung INR18650-29E 2900mAh.

C rate is the one hour discharge current. If your cells are 3000mAh, then 1C would be 3000mA (=3A). If you have cells in parallel, multiply the rate by the number of parallel cells.

So for example if the pack is made from cells with 3000mAh cells (sorry I don't know what Samsung INR18650-29E are rated at), and the pack is made with 5 parallel, then 1C would be 15A and 3C would be 45A.

Samsung rates the 29E cells at 2.75A continuous and 8.25A burst. That equates to 0.95C continuous and 2.85C burst using the rated capacity of 2.9ah. Don't run them over 1C for any length of time if you want them to last. The pack should be sized so that the cells don't give high currents all the time. If you want to play it safe and run at 1C, this means you should run at 1x your pack's ah rating of 14.5 ah, or about 15 amps continuous. 2C would be 2 X 14.5 = 29A.

And my cycletruck [with about 400-500lbs total combined weight] uses up to 54watt hours per-mile. Mostly less, but you need to calculate for maximum if you can't pedal a heavy load. Then you should add another 30% [or more] for degradation over the years you want it to be used. They don't hold the same capacity until they die; it is a gradual capacity loss.

If you are gentle with the lower capacity cells they will last much longer than high capacity cells.


Watt Hours: Calculating E-bike Range









http://vruzend.in/product2.htm












LiCoO2 lithium cobalt oxide are the best. That is what Tesla motors is using now. Lithium titinate will be even better.


How to make your batteys last longer
Never charge lithium ion cells to more than 4 volts each. Anything more than 4.2 volts will cause a condition where fire and explosion can occur. And 4 volts will make the cells last much longer. If your charger goes to 4.2 volts take the cells out before they have a chance to go any higher.
How to safely charge your batteries

How does Cobalt Work in Li-ion?


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