07-22-2025, 06:49 AM
21700's right now are cheaper, with a higher CDR and higher capacity..
I am not sure how Ebikes work with regards to battery swapping, or range extender packs.
Honestly, the prebuilt packs are hard to beat, price wise. The main reason to build your own is when you want to use known high quality cells and built them to a higher standards.
With DIY esk8, the The BMS is only wired up for charging. The esc itself handles the low voltage cutoff. This is done as the BMS cutting power, can be bugely dangerous, not only with the loss of brakes, but when one is braced for accelleration, and the voltage hits the threshold, and the BMS cuts power, then it is difficult to not streetface. It will almost always cut power when one is leaning on their front foot accellerating, and aoss of power causes one to fall. The more powerful belt and gear driven boards do not have great free roll, let off the throttle and it is almost like bitting the brakes.
On a bike, one is not.going to go flying over the handlebars if the BMS cuts power, and there are atill friction brakes to stop safely.
My weak hub motors have great freeroll, nearly as good as an analog push skateboard with good wheels and bearings.
With DIY esk8, one only needs a BMS to handle charging current, they can be a lot physically smaller, and fit into an already tight enclosure easier.
I am using Daly BMS's, dumb ones, as the smart BMS is always sending a bluetooth signal, and that paraSitic draw has killed many unattended packs. My BMS are rated at 10 amp charge, 20 amp discharge, but my latest model of same dimensions says 15 amps for both.
I have a smart JBD bms for 10-17s, and 15 amps charge, 30 amps discharge iirc but it is pretty big, and they have a smaller model i should have ordered instead.
Ebikes generally use energy cells, not power cells. The energy cells.in a 4p configuration can handle the draw without too much voltage sag.
I am using a 2p configuration in my esk8, so each cell needs to output more, so a power csll which will not.overheat, and not sag a lot.of.voltage is much more desirable.
Riding more sedately in cooler weather I'd get some morre range with some energy cells vs the power cells, but riding harder the power cells will actually provide more energy to the motors.
So cell choice should have a lot of factors considered. Price is a huge one of.course, but there are many asterix's involved in what is actually best for any given application.
Excellent data for informed cell choice would be max amp draw, average amp draw, and how the exiating battery performs with its cells. Often huge unknowns.
A lot.of.prebuilt battery packs won't say which cells they actually use, and.might not actually use the cells they claim that they do.
I am actually scared of my 2 7S prebuilt packs with their noname brand cells, and unknown build quality, hidden under the shrink wrap.
I am not sure how Ebikes work with regards to battery swapping, or range extender packs.
Honestly, the prebuilt packs are hard to beat, price wise. The main reason to build your own is when you want to use known high quality cells and built them to a higher standards.
With DIY esk8, the The BMS is only wired up for charging. The esc itself handles the low voltage cutoff. This is done as the BMS cutting power, can be bugely dangerous, not only with the loss of brakes, but when one is braced for accelleration, and the voltage hits the threshold, and the BMS cuts power, then it is difficult to not streetface. It will almost always cut power when one is leaning on their front foot accellerating, and aoss of power causes one to fall. The more powerful belt and gear driven boards do not have great free roll, let off the throttle and it is almost like bitting the brakes.
On a bike, one is not.going to go flying over the handlebars if the BMS cuts power, and there are atill friction brakes to stop safely.
My weak hub motors have great freeroll, nearly as good as an analog push skateboard with good wheels and bearings.
With DIY esk8, one only needs a BMS to handle charging current, they can be a lot physically smaller, and fit into an already tight enclosure easier.
I am using Daly BMS's, dumb ones, as the smart BMS is always sending a bluetooth signal, and that paraSitic draw has killed many unattended packs. My BMS are rated at 10 amp charge, 20 amp discharge, but my latest model of same dimensions says 15 amps for both.
I have a smart JBD bms for 10-17s, and 15 amps charge, 30 amps discharge iirc but it is pretty big, and they have a smaller model i should have ordered instead.
Ebikes generally use energy cells, not power cells. The energy cells.in a 4p configuration can handle the draw without too much voltage sag.
I am using a 2p configuration in my esk8, so each cell needs to output more, so a power csll which will not.overheat, and not sag a lot.of.voltage is much more desirable.
Riding more sedately in cooler weather I'd get some morre range with some energy cells vs the power cells, but riding harder the power cells will actually provide more energy to the motors.
So cell choice should have a lot of factors considered. Price is a huge one of.course, but there are many asterix's involved in what is actually best for any given application.
Excellent data for informed cell choice would be max amp draw, average amp draw, and how the exiating battery performs with its cells. Often huge unknowns.
A lot.of.prebuilt battery packs won't say which cells they actually use, and.might not actually use the cells they claim that they do.
I am actually scared of my 2 7S prebuilt packs with their noname brand cells, and unknown build quality, hidden under the shrink wrap.
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