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Power powerwheels

Gluktar

Jul 10, 2018
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I managed to pick up a free power wheels car for my 5 year old by posting an ad for “broken power wheels wanted for free”. Got it home, cut of the proprietary power wheels batter plug and hooked it up and it wasn’t broken, works fine. Now with a little sawzall work and a mini car battery I have a discount power wheels.

However, the drive motors, one for each wheel, are about the size of a D cell battery. This think is way to weak. So I want to keep it slow and somewhat safe. If I just put bigger motors on the existing gear boxes I expect that they will just explode. I am also trying to do this as cheap as possable. I am salvaging dc motors and it is hard to find 2 matching ones. I have got one out of a treadmill that is likely a tad too big. The other issue is it is 90vdc, and I have 12vdc and don’t want to get a fancy lithium battery pack. I was thinking I could use a boost converter like this:

https://www.amazon.ca/dp/B07568P3QL/ref=cm_sw_r_cp_api_FhdrBb64CBP3Q

If the booster is rated 900 watts but my motor is labeled 18amps, 100volts, is the motor really 1800watts or is that peak only? Can you think of a better way to get some more power on a budget. Oh, i was thinking of using mountain bike sprockets and chain as a gear box. That’s step 2...
 

kellys_eye

Jun 25, 2010
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If it is 18A at 'full load' then the motor is an 1800W motor.

The booster you link to is rated at 15A max so unsuited to drive your motor.

However, the drive motors, one for each wheel, are about the size of a D cell battery.
If you're planning to replace a 'D-cell sized motor' with an 1800W motor you need to seriously consider your mechanics!
 

Externet

Aug 24, 2009
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Seriously consider your mechanics after more seriously considering the safety of your 5 year old...
 

Gluktar

Jul 10, 2018
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Indeed safety is a concern. The max speed of a factory power wheels is 2.5mph. I plan on keeping it the same. Also, can I simply underpowered the motor. If the label says 18amps and 100volts and around 5000rpm. Since I will be gearing it down anyways, is there a way to know the max power draw at a lower voltage? And actually, I am just thinking, I did hook it up to the 12v battery and it spun away nicely but it felt pretty easy to stop. Is the torque greatly reduced with lower voltage, and is it liner? (10% of potential torque for 1/10 the voltage?) Or to put it another way, is there any point in under powering an electric motor or should I just find one in the 250-500watt realm?
 

kellys_eye

Jun 25, 2010
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If you're keeping the speed the same, all you will achieve is more torque. Is this actually required? The increase in supply voltage/current would make any battery powered solution very brief indeed.
 

Externet

Aug 24, 2009
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What gearing down does is increase torque, and powering that two+ horsepower 100V motor with 6-12V, the power draw will be around a tenth.

Perhaps you have overseen that keeping the original motors and replace/using a battery of the same voltage with larger capability (motorcycle type) would solve your wishes.
 
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Gluktar

Jul 10, 2018
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Perhaps. Will have to keep thinking this one through.

Thanks.
 

Tha fios agaibh

Aug 11, 2014
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A few years back my boy asked me if I could make his powerweels faster. Of course I couldn't say no to him.
So I put in a second battery in the front storage compartment and wired in an automotive relay that switches it from factory 12v to a turbodrive 24v. The relay is energized by a pushbutton that is pressed once the car is already moving, not just to look cool, but to limit the torque a 24v start-up would put on the gearbox.
 
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