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Add second motor to scooter?

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rollout

New Member
Howdy,

I have an electric scooter (48v with a 500w hub motor) that can't handle hills. I am considering adding a second motor with a chain or belt drive that can be used to augment the power going up hill. Mechanically speaking, it seems feasible (plenty of space and mounting spots). I am, however, illiterate in terms of the electronics.

What will happen if I tie in a second motor to the existing 4 batteries? Should they be able to handle a second motor for short durations? Other than using the charge more quickly? Or would the second motor rob power from the primary motor? I was thinking of a simple on/off button to engage the second motor as needed (like a turbo button).

If piggy-backing on the existing batteries is a poor choice? then what are the basics required to run a secondary system? Seperate battery, controller(?), motor, and more?

Thanks in advance for your answers and follow-up questions. I read thru a lot of posts on this forum and it looks like y'all will have some great ideas and advice.
 

smanches

New Member
Need more info. Battery specs, motor specs, speed control specs, etc.

Can't just make a wild guess.
 

rollout

New Member
The only specs I have on the existing motor are: v/350 I-48 (500w)/ 520z/f.

Gibberish to me, other than I knew it was a 500w hub motor.

I have not even begun to spec out the secondary motor. Before going too deep I hoped to find a direction first. So generically speaking, what might happen if you add a second motor to an existing system? I would imagine adding a second motor that is rated for a 48v power source and probably in the 250w to 500w power range.
 

smanches

New Member
You will most likely need a complete separate set of batteries, motor and speed control. If you had all that, you could use the second speed control kind of like a turbo boost.

I all of sudden have image of Kitt jumping over walls...
 

Hero999

Banned
It's the speed controller that's most likely to be overloaded, the battery will probably be fine, it'll just drain more quickly.
 

rollout

New Member
It's the speed controller that's most likely to be overloaded, the battery will probably be fine, it'll just drain more quickly.
If I could avoid having to install addtional batteries, that would be a big plus. I wouldn't mind adding a second controller for second motor.
 

marcbarker

New Member
Not enough oomph up hills sounds like not enough torque. Maybe the battery or controller is naff, can't deliver enough current ? 500 W is nearly a horsepower. The kind of power a motor-assisted bicycle has. Fit pedals?

Just adding another motor I think would work. Don't bother with a PWM control, just make it a boost switch. It would use up the battery more than twice as quick of course, maybe the battery would go flat before reaching top, and you have to push the rest of the way.
 
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smanches

New Member
The big problem with not using additional batteries is not just the excess drain, but their life will be decreased as well. The less you drain them, the longer life they will have. Not just less cycles, but also just general discharge. Keep them as charged as possible all the time.

If you have to replace them less than half as often as you do now, just a second motor would be fine. But if you have to replace them more than twice as often, it's not worth it.

Do you wear your batteries completely down often? That's the real killer. A second motor will make it that much easier.

If you only use the second motor as a boost motor, then two motors would work fine. If you want to run it all the time, then upgrade the existing motor as blueroom mentioned.
 
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tcmtech

Banned
Most Helpful Member
have you considered trying to just add a heavy duty switch that jumps the the input power going to the controller right to the output line to the motor?

I would be temped to try that and see if the controller is current limiting the power and not giving you full torque.
If you add the bypass (turbo boost button) and suddenly you have loads of power your controller is at fault.

As pointed out earlier 500 watts is a fair amount of power. Compared to human power that about 6 -7 time the continuous output a healthy person can produce.
If that motor doesn't feel like you have a few line backers giving you a push up the hill its either over rated and not actually capable of an honest 500 watts or your controller is limiting it too much or the battery is not capable of sustaining the needed current to drive it.

For short bursts an electric motor can produce far more than its rated power. The main concern with over loading your motor (if possible) is to keep it from getting to hot and your wiring getting to hot.

Your battery should handle it with little problem unless its already got one foot in the grave.
If It does its a good excuse to modify the system to take a bigger capacity battery and related wiring.
 

Hero999

Banned
THe controller might be limiting the current to protect the motor, disabling this feature might cause the motor to overheat if it's done for too long.
 

marcbarker

New Member
A Turbo Boost button sounds like fun! Just think of the wheel spins, wheelies and dirt power-slides you can do!, without a nanny PWM controller getting in the way...

Safest way I think (without having to hack the existing circuit) is to add a DPCO change-over relay and wiring, that basically switches over the existing "500W" motor directly to the battery.

Watch out for smoke, carry a bottle of water to put out a fire with (or drink it if there ain't). If the motor burns out (it probably won't because I think the battery is knackered), then at least that gives you an excuse to upgrade to a more powerful scooter.
 
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RODALCO

Well-Known Member
Some great clips on Youtube with battery powered bikes and the like.

Search under starter motor powered bicycles.

Amazing good torque although big 12 volt accu's are used.
 

marcbarker

New Member
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RODALCO

Well-Known Member
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