Upgrading a Powabyke.

[dermot]

Just after the turn of the century, I bough a Powakyke: http://www.powabyke.com/ which I then sold on second hand.

The SLAs in it have died again, so I'm in the process of replacing the three 12V 14AH SLA batteries with a 13AH NiMH pack.

I rather think it'll improve the range *and* the weight/handling quite a bit.

Just in the process of cracking the old pack open now - I'll document the process in pictures, if anyone is interested.

Powabykes have sold reasonably well in the UK market, so I suspect there may be a few bikes than could benefit from this sort of upgrade.

Since the Powabyke is only (I think) a 180W motor, it'll only be pulling 5A or so - not too difficult to manage.

The removable battery box is huge - I may even be able to fit a charger inside it with a waterproof mains connecter.

 

[NickF23]

Cool project,

There loads of them around so I imagine it might be helpful to some people. I've got a couple of powabykes that I restored. One of friends to ride around on and another as a backup bike for myself. with 36 volt nimh it should run forever!

I wondered if it would be possible to fit 48 volts of nimh in the pack. The controller seems to handle 48 volts fine but adding more lead to the monster heavy pack is not such a clever idea

 

[dermot]

Cool project,

I wondered if it would be possible to fit 48 volts of nimh in the pack. The controller seems to handle 48 volts fine but adding more lead to the monster heavy pack is not such a clever idea

Ah, now that I didn't know! I'm pretty sure there is space, but are you reasonably sure it won't blow up the controller or motor?

If it is reliable, it would probably make the performance quite acceptable.

 

[NickF23]

I'm not sure about the controller. The capacitors are rated at 50 volts, so a freshly charged 48 volt battery will exceed the rating at least until the voltage sags when under load. Basically it seemed to work fine. At 48 volts the current limit on the controller keeps the amps/torque unchanged so the only difference is a 5mph increase in speed. This shouldn't damage the motor as no increase in current means no increase in heat.

I also increased the current limit on my controller and this does increase torque and heat, so I improved the cooling by drilling lots of holes in the motor, not the most elegant solution but it seems to work ok.

There a vid here

http://endless-sphere.com/forums/viewtopic.php?t=856

 

[thethinwhiteduke88]

Hi Everyone
new to the forum. I've just bought a 5-speed Powabyke to commute to my place of work. The overall journey is 22 miles (round trip). I'm using a 36v lead acid battery. The bike manages the journey which includes several steep inclines with pedal assist quite easily. What I'd like to know is, is it possible to increase the top speed of 15mph to say between 20 -25 mph? I've done some web research and have seen info suggesting that Powabykes cannot be modified. What do you Guys think? Thanks in advance for any info or help.
Cheers!
Gary.

 

[fechter]

Anything can be modified

I'm not sure which model you have, but on their website it looks like it's probably a 200w brushed hub motor. If it goes 15mph on 36v, it should go around 20mph at 48v. Beyond this you might be overstraining the motor, but perhaps not. Hub motors are pretty resistant to overheating.

It may be possible to modify the existing controller to do 48v, but if that is difficult, a new brushed controller for 48v is fairly inexpensive from someplace like TNC Scooters. Even higher voltages are a possibility.

Either way, I think to go faster, you need a higher voltage, which means adding at least one battery. At a higher speed, the power consumption will be greater, so the range could possibly drop, although at 20mph you're not really into high wind resistance. With one more battery, you have more energy on board, so if you keep the speed down, the range will be increased compared to stock.

With some controllers, you can feed the logic portion from the 36v tap between batteries and put the full 48v to the main power input. This 'fools' the controller into thinking it's still running 36v (and keeps vital components from frying). I'm not sure if this trick will work on yours.

 

[NickF23]

Hi Gary.



I have a powabyke that runs at 48 volts and go's 20 mph. There's quite a few mods you can do with these bikes. Adding another battery in series is quite a safe mod to do. You will get no increase in torque due to the way the controller regulates current but you will get an extra 5mph. It might also be worth thinking about providing some extra cooling for the controller as it does get a little hotter, drilling a couple of holes through the plastic housing from the underside should do the trick.

See these threads for a bit more info


http://endless-sphere.com/forums/viewtopic.php?t=856&highlight=powabyke

http://endless-sphere.com/forums/viewtopic.php?t=401&start=15

 

[Altvamp]

I have never read so much twaddle as the posts here regarding increasing the battery voltage from 36V to 48V. It seems you think you are able to break the laws of physics!
Power has a direct relationship between votage and current (VxA=W), and to get more speed you need more power, to get ore power you need to increase the voltage, you can't change one without changing the other. With no current control an increased voltage will result in increased current flow through the motor, if you limit the current then you wil get no power increase and therefore no speed increase. Or to put it another way, if you are getting increased speed then that is an increase in power from the motor, which means an increase in power to the motor which means higher current flow.
Next thing, someone mentioned the capacitors rated at 50V, perhaps you should look more into how the controller works, usually the circuit is actually powered from a 12V regulator on the PCB, the only part of the circuit at full battery voltage is the battery input, the output MOSFETs and the motor, it's unlikely that any electrolytic capacitors will be present in this stage of the circuit, so increasing the voltage to the controller is unlikely to be an issue for the capacitors in the controlling circuit unless some are on the 36/48V rail in which case 50V is not a safe tolerance, they would need to be 100V rated to avoid risk of failure.
The only component in the contrller that is going to be affected by the voltage increase is the output MOSFETs as they wil be having more power through them, however these are usually very heavily rated so may be able to cope with it, though producing more heat. The most likely part to fail from the increased power is the motor, particularly at pull off or low gear ratios resulting in high required torque as this is when the motor is using most power as it's running slower.
It wil also be increasing the power dissipation of the onboard 12V regulator which is also at risk of overheating and failure.

 

[alsmith]

Decide what you want the bike to do before changing things, that way you can get what you need to meet your needs.

As said you can modify and change things to get to what you want.

My bike was originally a powabyke (from the first delivery of Mk 1 x-byke step-throughs). It now has a Lyen controller (up to 100V), a crystalyte 5300 that can handle many KW of power (originally 200W rated, around 450W peak), and two batteries that an be configured as 36V 30Ah or 72V 15Ah (originally 36V 5Ah).

 

[alsmith]

-- misunderstanding of reality cut --

Some bits are right in isolation but there is a chunk of misunderstanding in that. Ignore it.