[speedyxjs]

So i have bought a 2004 g-wiz (very cheap) for my Rover 45 conversion but i am now worrying about the performance.

I am connecting the motor to the 45's gearbox which i thought would give me acceptable performance but im now worried that the wiz's 48v system wont be very good at all.

Would a more powerful controller and a few more batteries solve this or am i better off looking for a better donor?

 

[brian_]

I had to look up the Rover 45... few outside of the U.K. will have seen or even heard of it. It's a variant of a Honda Civic, so that's over a ton of compact sedan... more than double the weight of a REVA /REVAi / G-Wiz.

Using the multi-speed transmission will allow the motor to work at peak power over a broader range of speeds, improving low-speed acceleration compared to a single-speed setup, but if attempting highway speed then performance will still be severely power-limited.

Is this the original 6.4 kW DC motor and lead-acid REVA, the 13 kW AC motor and lead-acid REVAi, or (unlikely because it was cheap) the REVA L-ion?

 

[speedyxjs]

Unfortunately it is the early DC motor.

I was thinking of possibly changing the controller for a more powerful one to get a power boost

 

[Duncan]

Hi Speedy

Can you tell us about the motor?
Rough size - weight and number of brushes

I'm thinking it's maybe a re-purposed forklift motor - and you CAN change the controller to get a LOT more power out of one of those

 

[brian_]

Unfortunately it is the early DC motor.

I was thinking of possibly changing the controller for a more powerful one to get a power boost

The most that a DC motor controller can do is nothing at all other than act as a closed switch. If the controller is limiting performance, it is doing that by limiting current. It could be limiting to protect the motor, to protect the battery, or to protect itself. Whatever the reason for a current limit, raising the limit will likely only help at low motor speed, since the performance at higher motor speed should be limited by available voltage.

If you increase battery voltage, then you might need a new controller which can handle the higher voltage (as well as more current).

 

[brian_]

Having just looked at the results of a Google image search for "REVA motor", and noting the 6 x 8V battery configuration, the REVA powertrain appears to to basically come from a golf car. Anything done to improve golf car performance will likely apply here... but it seems likely that by the time it puts out enough power to get a Rover 45 up to highway speed, or to accelerate the Rover at a rate acceptable to most people, there couldn't be any of the REVA components left other than the motor itself (because the system voltage will need to be much higher), and you could have started with any available DC motor of a suitable size.

I suppose it depends on your expectations for performance, but consider this: the least powerful engine for that Rover can put out 76 kW (102 hp), and even if it average only half that while accelerating (because it isn't at optimal speed), a 6.4 kW motor will fall very far short. Even assuming the electric motor is always at peak power (which is very far from true), and you double the output by pushing the motor harder, it will still be relatively slow.

Of course you could treat it like a drag racing car, feed the motor three times the stock voltage, and run it at current levels which take it to the edge of meltdown.

 

[speedyxjs]

Thanks for the replys. After some thinking, i might resort to my plan A which is to convert my K11 Micra i use for running round town. The idea of the rover is i want the engine for my MG midget conversion and would end up with a car with no engine which would have been a good conversion but i don't think i will be able to afford the same performance in the rover.

the Micra weighed 740kg with me in it last MOT so is much closer to the wiz's weight.

 

[brian_]

You might want others to validate my observations about potential performance before abandoning the original plan, but I think you're now headed in a better direction. For assessment of the potential of the REVA parts, it would help to know the size of the motor - common brushed DC motors are often just described by their diameter.

Just curious: why not just convert the Midget with the REVA parts? My guess is that you want an EV for low-cost (and low-performance) transportation, and the Midget as a more powerful sport car, which would make sense.

 

[speedyxjs]

Im planning on getting the wiz on a ramp tomorrow to check out the size of the motor.

The midget is intended to become a track car so will need to stay ICE for now but maybe when EV parts and batteries become cheaper and more efficient

 

[speedyxjs]

Finally managed to measure the motor yesterday and it is about 6 1/2 inches diameter. Not sure how many brushes and it is still in the car so not sure on weight. Couldn't see a plate on it with any info

 

[Duncan]

6 1/2 inches is too small to be any use for a car - be OK for a motorbike or a go kart

 

[MattsAwesomeStuff]

Finally managed to measure the motor yesterday and it is about 6 1/2 inches diameter.

That's very, very small. Motorbike small. It's small for a golfcart small. Probably 40lbs?

I have an 8" motor in my motorbike, which is probably a bit oversized, but, you'd never use one even this small for even a light car.

To move the Rover you want minimum a 9" motor.


The G-Wiz's motor is basically the smallest motor you'd even consider using on something the size and weight of the G-wiz itself, which only went 50mph (hence probably why they doubled the size of it in later models, since it wasn't even powerful enough for that, and *still* got a rep for being a an ugly turtle). It doesn't bode well for something 2-3x that weight like the Rover.


You could maybe run that 48v motor at 150v, with tons of forced air cooling, but, that's really, really pushing it's abilities. You'd absolutely be threatening it's duty cycle just to maintain highway speed, wheras most underbuilt EVs you're only threatening it during hard acceleration.

But, you gotta piss with the cock ya got, so, you could probably make it work if you had to.

 

[speedyxjs]

Yeah, i was surprised about how small it was lol

 

[bigpie]

But, you gotta piss with the cock ya got, so

Off topic but best quote ever. I can't wait to be able to use that one.