Gruber
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M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By PandaBlue
#148022
Hi i’m not sure if this forum is the best place to post as im not modifying a Power Wheels toy but something similar.

Basically I took my kid’s 6V 17000rpm motor scooter and started mucking around with it because... well you know why lol.

So the whole thing used to have a 6v 4.5ah battery with a 380 motor with 17000 rpm and a regular gearbox. Wires seem thick enough.

I bought 2 RS550 12v motors at 30000rpm with gearboxes already. I installed 1 but it was swerving to the left (3 wheel scooter) so I installed the second one. I installed a 12v 9ah UPS battery and upgraded the charger to a 12v 1a device. I also installed pneumatic tires same diameter as the original. The whole scooter probably weighs 25lbs. My kid weighs maybe 35lbs. So total weight 60lbs. I have no idea what the specs of the motor are other than seeing max 270 watts which is probably before stall.

So I guess the general question is, any idea how much power I would be drawing upon launch and when already moving - based on the experience of folks here. Is the battery enough to last like an hour without killing the SLA? Will I blow anything up? Do I need to install anything else to make it safer? Any advice will be appreciated as its the first time ive done this.
User avatar
By chart2006
#148094
You won't get an hour of drive time out of a 9ah battery that's for sure. As for the other questions there's no way to answer that. For starters we know nothing about the gearbox and the pinion gears you purchased. Did you buy gearboxes that have steel 1st gears? What was the tooth count on the pinion? Pneumatic tires will definitely help with traction but they are hell on the motors and gearboxes especially if the 1st gear is plastic. It's almost guaranteed you'll eventually smoke the gearbox with rubber tires if you haven't replaced the 1st gear. I wouldn't worry too much about the SLA as they're pretty versatile batteries. Just try and adhere to the maintenance requirements like putting them on a charger once a month and don't let them completely drain. If possible get a larger capacity SLA. My go to is 18ah as it fits in all my PWs. Obviously I don't know what would fit in your scooter so 18ah . I'd also suggest adding a fuse. If you have dual motors at 12V and 270 watts you're looking at 22 amps per motor so a 40 amp fuse would be good. At 40 amps it would just be easier to get a breaker used in car audio systems - that's what I did for mine.

What it boils down to is if the gearboxes have steel 1st gears and you add a 40 amp fuse/breaker to it you should be fine though I'm not sure how well the 550's will hold up with rubber tires. Most people move up to 775s.
User avatar
By PandaBlue
#148200
Thanks! Trying to get a hang of this modifying thing. Im now on 12v 18ah batteries - after 30 minutes or so (full throttle going round and round) I notice a drop in speed. 2x 550 motors with a 38lbs child on it (the motorcycle is small and light, maybe 20-25lbs total). I’m using a 500 watt ebike controller and it gets too hot to touch after 30 mins.

Do the rubber tires make a huge difference in both top speed and power draw? Maybe that’s whats causing my high power consumption.

Also I still havent learned the gearing so i havent opened it up. First time we tried it without pwm or a controller the bike did a wheelie. Maybe I have too much torque and need different gearing? Trying to google the gearing but cant fully understand as there are 3 gear pieces plus the one attached to the shaft. Mostly people talk x tooth but not sure which gear I should be looking at.

Motor and gearbox : http://s.aliexpress.com/RRnmqMJN
User avatar
By PandaBlue
#148201
Oh and a followup question maybe someone here can answer... for these types of motors is it better to use a PWM controller or an EBike controller? I noticed a lot slower acceleration with the ebike controller and voltage was pretty much flat 12v althroughout, I think it’s controlling current rather than voltage. I’m trying to figure out if ebike controllers were not meant to be used with these little motors.
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