Question about batteries

[103Alex1]

In use, you rarely see that sort of current. You have to be going fairly slowly at maximum throttle.

It's pretty standard during acceleration from standstill on full throttle on mine. Also on steep climbs >15% 'flat-out' on full throttle it'll put that out continuous round the 13-17mph range for a considerable time. I don't run it continuously like that on throttle-only (in fact hardly ever ride the bike throttle-only).

It does make me think, however, that a 48V 25A system wouldn't that give much discernable improvement than is already being achieved, apart from maybe a bit more help on a throttle-only climb or to compensate additional weight ? The new variant BMS controllers with displays like the S12S look to be running considerably lower amps at 36V (22A) so presumably the power differential will be much more noticeable with these ?

Customer comments left on BMS website along with CA and other measured figures also seem to bear out that the controller will pull up to 30 amps given enough battery : http://www.bmsbattery.com/controller/364-universal-brushless-hub-motor-controller.html

 

[iain85]

Does anyone know if you can safely wire the Bms battery lifepo battery blocks in Series (or is it parallel ?!) to get twice the voltage? Ie I've got a 36v 20ah battery can I get another to make it 72v 20ah? Will my ku123 and bafang 500w handle it? Expected speed increase? Ta

 

[Deleted member 4366]

In a word, no.

the KU123 has 63V capacitors. 16S is as high as you dare go at about 67.2v max.

The motor will handle it as long as you keep the speed up.

 

[Alan Quay]

You should be ok to use them in series, but I've never tried it.

Be aware that 72v DC is getting into the danger zone as far as shocks go.

A DC shock is more dangerous than an AC shock, because of the chance of muscle contraction.

Just be careful is all I'm saying. It only take 20mA to stop the heart.

 

[iain85]

Thanks, didn't even consider the shock implications! All though I suppose that's true of all high voltage ebikes. The thought of getting electricuted doesn't appeal at all!

Any idea of what controller could handle the batteries wired for 72v and what speed one could expect with the bafang motor?

 

[Elecman]

Interesting thread. I think some of this info is starting to sink in for me as well ! It's like being back as school ! Great info chaps.