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Would a 700 watt electric motor be sufficient for my needs? Answered

I'm have started building a small electric cart, I plan on using 2 350watt motors to power it.

I estimate the final weight of the cart (with me on it) to be around 250 pounds, would these motors be able to effectively propel the cart? 



8 years ago

Define "effectively".

They'd move it, but how fast depends on the rest of your design and the terrain you'll be crossing.


Answer 8 years ago

I don't need it to go all that fast, maybe a top speed of 30-40km an hour.

This project is more a "proof of concept" kind of thing.


8 years ago

700w will deffinately be enough, but 700W/12V=58A, which is a very large amount of current, similar to what a car uses to start the engine. It will definitely be enough power, but the main problem will be powering it. Most car batteries are about 30-50Ah (ampre-hour), so you could only run it for about half an hour-1 hour on one battery, so I would recommend getting several and making sure they are definitely rechargeable. Also, 250lb does sound like a lot of weight, it should be possible to get it down to about 100 or so, then you could use less powerful motors and go faster/longer. Gearing is also important. I don't know much about gearing, but you definitely need to get it right, because the torque-speed ratio is inversely proportional, so it needs to be balanced. If the wheels spin too fast, it won't have enough torque to move it anywhere, and if it can move a heavy weight, it won't go very fast, but as I said, I only really know about electronics, but hopefully you can find an equation to calculate the gearing to use.


8 years ago

yes - A lot depends on how you approach gearing and what you expect in acceleration and top speed.

Dependingon the motor voltage and your power supply you may be able to squeeze 150 miles out of 4 car batteries.


There will be a huge improvement if you can get weight below 100 lbs. Not impossible - Aluminium, chassis/body. use of plastics.

The biggest weight adder are the battery(s) and the driver.


8 years ago

700 watt is about 1 horsepower. There bubble cars which use engines of 1hp. You won't be going specially fast but you would be moving at a decent enough rate.