powabike overvolting!!

[jimmyhackers]

ive been tasked with making a new battery for my friends fathers powabike.

weirdly the original battery was a 10s (42v battery) with no balance leads or balance boards.....probably why it failed.

i plan on making a 48v battery for it....however upon dissection of said ebike i noticed the controller itself said (36v) on it..... meaning it was overvolted to begin with.

so my question is......being as its brushlesss n all.....will i get away with pumping 48v through it?

thanks in advance

jim

 

[MadRhino]

The controller was right. Battery voltage is calculated nominal, not at full charge. 10s is 37v nominal. Overvolting with the same controller can reach the limit of capacitor rated voltage, that would be 60v full charged battery so 14s is safe without needing any mod to the controller, other than changing the low voltage cutoff setting.

 

[billvon]

The controller was right. Battery voltage is calculated nominal, not at full charge. 10s is 37v nominal. Overvolting with the same controller can reach the limit of capacitor rated voltage, that would be 60v full charged battery so 14s is safe without needing any mod to the controller, other than changing the low voltage cutoff setting.

. . . and the rating of FETs, diodes and IC's.

Also, keep in mind that a motor drive FET that is rated to 50 volts cannot be used at 50 volts, since during regen (and even normal PWM operation) it will see voltages in excess of 50 volts. You need some margin (which varies with design.)

 

[MadRhino]

The controller was right. Battery voltage is calculated nominal, not at full charge. 10s is 37v nominal. Overvolting with the same controller can reach the limit of capacitor rated voltage, that would be 60v full charged battery so 14s is safe without needing any mod to the controller, other than changing the low voltage cutoff setting.

. . . and the rating of FETs, diodes and IC's.

Also, keep in mind that a motor drive FET that is rated to 50 volts cannot be used at 50 volts, since during regen (and even normal PWM operation) it will see voltages in excess of 50 volts. You need some margin (which varies with design.)

That could happen. Yet I am using 100v rated mosfets and been charging 105v for years, abusing power everyday.

 

[d8veh]

There's very little chance your Powabyke controller will work with 48v. You need a 48 controller for that. Most 36v controllers can manage 12S, so that would be an option for 20% more speed and torque. Much of what's on Powabykes is bespoke stuff, which makes swapping things around tricky. That's even worse if you have one of the old brushed motors.

It worries me a lot that you're going to build a battery and you didn't know that a 10s battery is 36v and it charges to 42v. Everybody has to start somewhere. If you're not sure of what your doing, always ask here first. Everything is easy when you know the answers. Lithium batteries of all types can be very dangerous if you get something wrong.

 

[MadRhino]

True, but worth a try. Those small controllers are very cheap anyway. If it was brushed, then no chance it would work at 14s, but no damage could occur other than frying the 15$ controller. If it is brushless I give it 50% chances and if it doesn't live, the option to buy a 48v controller still rides.

Battery building is another story, especially with cells that are charging 4.2v. :wink:
You need to know what you are doing, and the charger that you will supply with it must be within cell spec. and reliable.

 

[dogman dan]

I'm sure the motor can handle 13s, or even 14s. But the controller is the unknown. If you can open it and see 60 or 63v capacitors inside, then there is a possibility it can stand 14s.

Or,, it might have a high voltage cutoff protection, that limits it to 10s or so. Might sneak under that at 12s,,,

 

[d8veh]

You're all wasting your time until OP shows us what bike it is. Most of the Powabykes used a brushed motor, and whichever bike it is, brushed or brushless, the control systems are quirky, so you can't just exchange the controller. You'd have to chuck everything apart from the motor. Brushed controllers with PAS function are like rocking horse shit.

 

[jimmyhackers]

muchos replies...many thanks guys.

i knew i should of done this before asking but i was lazy. Anyways so i had a little look inside the controller and a 12s (48v) battery works fine. the caps were the lowest rated item at 60v.

im not sure if this bikes limited to 15mph or not, as said the controller is rather weird and all in chinese. plus the tyres were flat and it was raining so i didnt ride it.

the controller and hub is brushless. which is why i was happier to overvolt it (no silly brushes to burn out) however the controller is a rather tiny one which is why i asked on here if anyone knows a bit more. and now after ive investigated maybe you guys know some more

i never knew the rating on on controller was nominal voltage. is it like that on every controller? seems weird to me but oh well.

i suppose it explains why my 48v controller took upto 60v without needing modification.

thanks for the help guys

 

[d8veh]

Can you show us a picture of the bike?

 

[jimmyhackers]

i can but its at my mates house (as its his dads bike)

when i go round next ill snap a pic for you guys.

i warn you now its not very exciting as far as ebikes go ;P

 

[d8veh]

I'm not looking to be impressed. I just want to know which model it is. All the common ones used brushed motors. Only the later X bikes had brushless motors. The X6 had both types. They changed it halfway through the production run.