Hi
I’ve been toying with the idea of converting an Aprilia RS50 for years and have finally sourced the donor bike. It’s in really good condition but I’m happy to have a go at converting to electric and then putting it back to gas later if it doesn’t turn out as expected. I know I need to cut the rear of the swing arm to get the QSMotor hub in and make up some adapter plates to secure it down, but I’ll use a spare swing arm/frame for this and keep the original so I can revert back.
Having looked around at other conversions, and done a couple of Stealth bike type eBike builds, I’ve ended up basing the build on the QSMotor 17” hub motor rated at 4,000w - I need to limit this to 4,000w so it can still be classified a 50cc moped in the UK. The bike is still registered with the DVLA as a 50cc and even has MOT for another 10 months so it should be relatively easy to change to electric on the V5 once it’s built and I’ve even got QSMotors to supply me with a certificate confirming the maximum continuous output rating of the motor is 4,000w
So the question and request for help from all you more experienced builders out there is my maximum speed design goals for this project. I want it to achieve 50 mph max which the donor bike can actually achieve as a 50cc petrol engined back as it’s been derestricted. I’ve spoken at length to QSMotors and studied the motor spec sheet for what would be the V3 motor, and understand I can easily get 50 mph out of it on something like an Aprilia RS50 (it’s a light aluminium frame) but I have to be running at 72v with a max output of 100A to achieve this speed.
I don’t have access unfortunately to anything like Leaf cells as I’ve struggle to source anything at decent cost, and so have gone to a couple of eBike battery pack manufacturers who can all produce me a 72v 30Ah - 40Ah pack using something like HG cells, but all of them are telling me if I push the pack/cells to anything above 60A max for any length of time I’ll end up with voltage sag and likely I will wreck the cells/pack quickly.
Any advice here on what I should be looking at for a battery pack? I’m not looking for massive range; 25 - 30 mile range is acceptable and average speed for this would be 25-30mph - the 50 mph design target is most likely only going to be used for 10 - 20% of the range tops. I’ve also got plenty of space in the frame for the pack itself particularly in the area where the 50cc engine is currently as this is covered by the fairings so I can get a decent sized rectangular pack sitting almost vertically low down in the bike which will help with keeping centre of gravity low, and the controller can be mounted in the area where the petrol tank is currently.
I’d also like to source a battery pack with BMS/Charger for max £900 - £1,000 - I can get the motor / controller for £600 so am looking at a total cost of parts for the conversion around the £1,500 mark.
Just to complete the picture QSMotors would supply a Kelly KEB 72601 controller with the motor. I know there are better controllers out there but looking at what I’d be running the motor at it seems acceptable. Again, any opinions/advice would be appreciated on this as well.
I’ve used a whole host of rpm/speed/tyre calculators to look at what the speed is I’m going to get at different A outputs at 72V. For reference the wheel/tyre combo is approx 18.8 inches in diameter.
Anything you guys can help with here would be most appreciated.
I’ve been toying with the idea of converting an Aprilia RS50 for years and have finally sourced the donor bike. It’s in really good condition but I’m happy to have a go at converting to electric and then putting it back to gas later if it doesn’t turn out as expected. I know I need to cut the rear of the swing arm to get the QSMotor hub in and make up some adapter plates to secure it down, but I’ll use a spare swing arm/frame for this and keep the original so I can revert back.
Having looked around at other conversions, and done a couple of Stealth bike type eBike builds, I’ve ended up basing the build on the QSMotor 17” hub motor rated at 4,000w - I need to limit this to 4,000w so it can still be classified a 50cc moped in the UK. The bike is still registered with the DVLA as a 50cc and even has MOT for another 10 months so it should be relatively easy to change to electric on the V5 once it’s built and I’ve even got QSMotors to supply me with a certificate confirming the maximum continuous output rating of the motor is 4,000w
So the question and request for help from all you more experienced builders out there is my maximum speed design goals for this project. I want it to achieve 50 mph max which the donor bike can actually achieve as a 50cc petrol engined back as it’s been derestricted. I’ve spoken at length to QSMotors and studied the motor spec sheet for what would be the V3 motor, and understand I can easily get 50 mph out of it on something like an Aprilia RS50 (it’s a light aluminium frame) but I have to be running at 72v with a max output of 100A to achieve this speed.
I don’t have access unfortunately to anything like Leaf cells as I’ve struggle to source anything at decent cost, and so have gone to a couple of eBike battery pack manufacturers who can all produce me a 72v 30Ah - 40Ah pack using something like HG cells, but all of them are telling me if I push the pack/cells to anything above 60A max for any length of time I’ll end up with voltage sag and likely I will wreck the cells/pack quickly.
Any advice here on what I should be looking at for a battery pack? I’m not looking for massive range; 25 - 30 mile range is acceptable and average speed for this would be 25-30mph - the 50 mph design target is most likely only going to be used for 10 - 20% of the range tops. I’ve also got plenty of space in the frame for the pack itself particularly in the area where the 50cc engine is currently as this is covered by the fairings so I can get a decent sized rectangular pack sitting almost vertically low down in the bike which will help with keeping centre of gravity low, and the controller can be mounted in the area where the petrol tank is currently.
I’d also like to source a battery pack with BMS/Charger for max £900 - £1,000 - I can get the motor / controller for £600 so am looking at a total cost of parts for the conversion around the £1,500 mark.
Just to complete the picture QSMotors would supply a Kelly KEB 72601 controller with the motor. I know there are better controllers out there but looking at what I’d be running the motor at it seems acceptable. Again, any opinions/advice would be appreciated on this as well.
I’ve used a whole host of rpm/speed/tyre calculators to look at what the speed is I’m going to get at different A outputs at 72V. For reference the wheel/tyre combo is approx 18.8 inches in diameter.
Anything you guys can help with here would be most appreciated.