Upgrading Aurora

[EddieH]

I have been thinking at some time in the future that I might upgrade my Auroro bike from 36v to 48v. Do I just need to change the motor and battery or is it more complicated than that?

 

[Deleted member 4366]

It depends what you're trying to achieve. The motor can do much more than Alien allowed it to. If it's more climbing power you want, you only need to increase the current to about 22A for which you need a new controller and battery. If you want to sustain a higher cruising speed, a 48v battery and 20A controller will make it fly, but the motor might get a bit hot on long steep hills.

I think the Aurora's BPM is sensorless, which means you can't use those nice downtube batteries with integrated 20A sinewave controllers from BMSBattery, which would otherwise be ideal. It might be worth checking if yours is sensorless. You could use the same batteries without the controller, but then you need to find a way/place to install a controller like the 22A S09P.

 

[EddieH]

Thanks for the help. Basically I was thinking of giving it a it more power as I am quite heavy and thought that might improve the performance. Luckily I live in Suffolk so not many hills to worry about

 

[Deleted member 4366]

Power is the product of speed and torque. Torque feels like power because it's the force that accelerates the bike. On a hub-motored bike like yours, the torque is more or less directly proportional to the amps from the battery. The motor can only spin to a certain speed, which depends on the battery voltage. Your motor is about 20 mph at 36v, so it'll do 26 mph at 48v. When you increase the battery voltage, you also get a proportional increase in torque, but a lower efficiency at low speed, which could be a problem if you had hills to slow you down.

You should therefore adjust the speed of your bike to the speed that you want to ride by choosing the right voltage, and then adjust the current to what you need for your weight and the steepness of hills.

There's no exact answer to what you want. Everything is a compromise, but if you're happy with 20 mph, you only need to increase the amps from the battery to 22A, which is about the maximum that your motor can deal with. If you want more speed, you need to get a higher voltage battery. 12S lipos will get you 20% more speed and torque, and a 48v battery will get you 30% more.

 

[selrahc1992]

Power is the product of speed and torque. Torque feels like power because it's the force that accelerates the bike. On a hub-motored bike like yours, the torque is more or less directly proportional to the amps from the battery. The motor can only spin to a certain speed, which depends on the battery voltage. Your motor is about 20 mph at 36v, so it'll do 26 mph at 48v. When you increase the battery voltage, you also get a proportional increase in torque, but a lower efficiency at low speed, which could be a problem if you had hills to slow you down.

You should therefore adjust the speed of your bike to the speed that you want to ride by choosing the right voltage, and then adjust the current to what you need for your weight and the steepness of hills.

There's no exact answer to what you want. Everything is a compromise, but if you're happy with 20 mph, you only need to increase the amps from the battery to 22A, which is about the maximum that your motor can deal with. If you want more speed, you need to get a higher voltage battery. 12S lipos will get you 20% more speed and torque, and a 48v battery will get you 30% more.

i guess from that that a controller that could modify voltage and amps would be able to provide a setup with a single speed hub gear with lots of grunt low down (say 36V and 22A) and high speed (say 48V) - is this too simplistic, and why hasnt it been done then?

 

[trex]

you need a battery that can deliver - and there is the legal issue of 250W limit.

 

[D8ve]

i guess from that that a controller that could modify voltage and amps would be able to provide a setup with a single speed hub gear with lots of grunt low down (say 36V and 22A) and high speed (say 48V) - is this too simplistic, and why hasnt it been done then?

A realy good question.
A buck/boost converter can provide variable voltage from a fixed supply.
This could give you 10 volts and lots of amps for starting off and then 100 volt low current for high speed cruse...
That is the theory anyway. The problems are efficiency and cost.
The losses vary from 5 to 40% so the battery would have to be 5 to 40% bigger for the same energy available.
The converter also has cost implications. Both weight and money.
Design of a high quality (efficient) converter with long life will cost finance and time. Something normally only the big brands could afford.

The other cost is weight.
When every gram counts is it better to add more battery or controller?

Has it been done?
I don't know. Perhaps Panasonic did this wIt's their drive?
It could improve efficiency bye running at best voltage but could also cost in the converstion losses?
It would add a layer of complexity and reduce reliability.
A good idea for the hypermile section but perhaps not in current use.
(Unless someone knows differently)

D8ve

 

[Deleted member 4366]

i guess from that that a controller that could modify voltage and amps would be able to provide a setup with a single speed hub gear with lots of grunt low down (say 36V and 22A) and high speed (say 48V) - is this too simplistic, and why hasnt it been done then?

It's been done a different way by Xiongda. They use the software in the controller to reverse the direction of the motor. Their motor has a double clutch. When it rotates one way, the internal gears give low speed and high torque, ant the other way it gives higher speed with lower torque - obviously both in the forward direction. It's a very clever idea that's robust and effective. It's what I have in my bike now.