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Power wheels - dual 12v motor upgrade

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centexk5

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Last year I bought my daughter a power wheels Silverado because she wanted a truck like daddy's. After driving it for a while she got out and looked at it and said daddy I need more power so I can rock crawl with you. Currently it's a single wheel 6v. So after some online searching I found the drive motor and gear assembly with 12v motors for $15/ea on Amazon and got two of those ordered up. The body is already cut for dual motors and the tires are already setup for both to be drive tires.
IMG_20200404_113844.jpg IMG_20200404_113850.jpg

Was getting ready to wire it and did a little research on the relay board and turns out the relays are only setup for 6v DC. So now I've gotta source some small 12v DC spdt PCB mount relays or find a 2ch 12v relay board that doesn't come from disease central. Doesn't make it easy that hobby stores are closed and radio shack no longer exists.

So just like daddy's blazer, this is going to be put on hold while waiting for parts.
 
Got a good ohmmeter? Measure the resistance of the coil of one of the relays, and get two heavy resistors about the same resistance and put one in series with each coil.
Or, depending on the circuit, if both wheels turn on and off at the same time, wire the coils in series. Each one will get 6 volts.
 
Do you just need to replace the relay on the PCB or a whole new relay board? If just the relay then there are several component outlets you can order from Mouser, Arrow, Jameco to name a few.
And then when you find that those brushed motors don’t have enough power you can upgrade to BLDC. :D

Helpful to have a pic of the board/relay. :thumb:
 
rampage said:
Do you just need to replace the relay on the PCB or a whole new relay board? If just the relay then there are several component outlets you can order from Mouser, Arrow, Jameco to name a few.
And then when you find that those brushed motors don’t have enough power you can upgrade to BLDC. :D

Helpful to have a pic of the board/relay. :thumb:
Click to expand...

I can find the relays but everything is on a multi week backorder because Corona. Here's a photo of the board.
IMG_20200404_174814.jpg

tRustyK5 said:
I converted my daughter's Power Wheels Jeep to 24 volt way back in the day.

Click to expand...

Holy crap that's hilarious hahaha
 
You misunderstood. Hook the coils in series. Leave the contacts hooked in parallel to the 12 volts.
The coils are what is setup for 6 volts. The contacts don't care as long as its not too much current or the voltage is so high it arcs.
From looking at the top of that board, looks like the two diodes are to prevent back EMF from putting a voltage spike on the control line when the relays drop out. And the whole thing looks like it might be very easy to rewire it so it will work on 12.
If its not potted with an opaque coating, take a picture of the other side. We might not even have to modify the board. If its wired the way it might be, we can just modify the control wires.
 
That girl is going to be so disappointed when she gets a real Jeep and it won't burn out like that......
A little rubber on those tires, and she would be flying.
 
Fordum said:
You misunderstood. Hook the coils in series. Leave the contacts hooked in parallel to the 12 volts.
The coils are what is setup for 6 volts. The contacts don't care as long as its not too much current or the voltage is so high it arcs.
From looking at the top of that board, looks like the two diodes are to prevent back EMF from putting a voltage spike on the control line when the relays drop out. And the whole thing looks like it might be very easy to rewire it so it will work on 12.
If its not potted with an opaque coating, take a picture of the other side. We might not even have to modify the board. If its wired the way it might be, we can just modify the control wires.
Click to expand...
IMG_20200404_200215.jpg
 
Thats perfect. All I have to do now is stay awake long enough to study it.....
I'm sorry, but this turkey hunting is beating me down. I'm going to crash right now, get up at 4 in the morning and stagger through the woods with a shotgun for a couple of hours.
When I get back tomorrow after that, I'll study it and see what we need to do. I downloaded it, and can zoom in as much as I need to.
There are some other electronics techs on here in better shape than I am. You guys feel free to jump in.
If each relay is for one motor and the reversing is done elsewhere, then it should be easy. If one relay is forward and the other reverse, then we will need a resistor. We should be able to get the coil resistance off the model number.
Everybody discuss, I'm gone.......
 
tRustyK5 said:
I converted my daughter's Power Wheels Jeep to 24 volt way back in the day.

Click to expand...
How long did the plastic wheels last?
I put a 12 v battery in my boys car and in a few weeks there's not much left, I am trying to figure out a replacement.
For the record I just replaced the 6v battery with a 12v nothing else.
 
They'd last a while, and I'd just replace em when they wore through. It was easier on everything to just let em spin, and it taught my daughter how to counter-steer and stuff. At the time I saw some guys putting inner tube rubber around the tires, but that was enough traction it just broke stuff.
 
tRustyK5 said:
They'd last a while, and I'd just replace em when they wore through. It was easier on everything to just let em spin, and it taught my daughter how to counter-steer and stuff. At the time I saw some guys putting inner tube rubber around the tires, but that was enough traction it just broke stuff.
Click to expand...
I contemplated the rubber coating, it might be good I am in only at 12v not 24v, they only spin for a couple of seconds then they launch
 
Might work...but the "gas pedal" is really just an on-off switch. 100% WOT, or brakes locked. How the motors mount get tore the hell up when there is any sort of traction. At 12 volts it should be less bad, hell most of the power wheels came as "2 speed" units anyways. The speed selector just switched from 6 to 12 volts. That's how my daughters was before we messed with it.
 
tRustyK5 said:
Might work...but the "gas pedal" is really just an on-off switch. 100% WOT, or brakes locked. How the motors mount get tore the hell up when there is any sort of traction. At 12 volts it should be less bad, hell most of the power wheels came as "2 speed" units anyways. The speed selector just switched from 6 to 12 volts. That's how my daughters was before we messed with it.
Click to expand...
I did notice the motor mount is moving, looking at ways to reinforce
 
Fordum said:
Thats perfect. All I have to do now is stay awake long enough to study it.....
I'm sorry, but this turkey hunting is beating me down. I'm going to crash right now, get up at 4 in the morning and stagger through the woods with a shotgun for a couple of hours.
When I get back tomorrow after that, I'll study it and see what we need to do. I downloaded it, and can zoom in as much as I need to.
There are some other electronics techs on here in better shape than I am. You guys feel free to jump in.
If each relay is for one motor and the reversing is done elsewhere, then it should be easy. If one relay is forward and the other reverse, then we will need a resistor. We should be able to get the coil resistance off the model number.
Everybody discuss, I'm gone.......
Click to expand...

The two relays are for forward and reverse. They flip flop the power and ground to the motor.
Using a resistor on each line going to the coils would be a sneaky way of doing it. The coil resistance is 100 ohms and rated at 360 mW so you’ll need to get two 100 ohm resistors rated at 1/2 watt (minimum). When looking at the top side of the board where the components are, locate the 4 prong connector. The two wires we are interested in are the two on the left. Cut each of those wires and insert a resistor in each one.

Now let’s hope that with the increased voltage the current the motor draws isn’t more than 10A. :whistle:

Here’s the data sheet for easy reference:

https://www.westfloridacomponents.com/mm5/graphics/K06/HF3FF-012-1ZST-257.pdf
 
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From the digging around I've done this morning, the motor will pull more than 25 amps in the grass with one person claiming 35 amps. That's a ton.

Also just realized I bought 30,000rpm motors instead of 10,000rpm like is stock. Oops.
 
I was hoping Rampage would jump in.
I worked out how the relays worked last night, but was too tired to try to post anything. Plus I didn't really trust myself to post something coherent.
He also found a better version of the spec sheet than I found yesterday.
BTW, as the relays are configured, you get dynamic braking.
His idea of putting 100 ohm resistors in the two control lines was my first thought, however, check out the image I posted. Zoom in if its too small. I had to download the original images so I could zoom them.
I'm pretty sure that the pin on the other end of the connector is the power source for the relays. One resistor in that line would do the same job as two in the others.

I have been trying to figure out where he could find a resistor. I briefly considered a light bulb, but the resistance change due to voltage is too great. And none of the bulb specs show current draw at different voltages.
Don't know what kind of stuff he has laying around in his "parts room", polite name for junk room, but he might find something that has one in it.
Color code is Brown Black Brown.
But, I am beginning to think that we need to back up and punt. 25-35 amps are going to seriously shorten the life of those relay contacts.
Diesel4me's link sounds like the best way to go at this point.
Simply hook the red lead from the board to the top center stud, the black lead to the side stud, the two control leads to the two spade terminals, and the white and blue wires to the two outside top studs.
If the car runs backwards, swap the two spade wires.

Note: the spec sheet for the new contactor does not tell if you get dynamic braking.
What will happen when going from 10K to 30k RPM, should be exciting. I would not let anyone in the car when its first powered up. The sudden acceleration from 0 to 30K instead of to 10K might snap the mounts and launch the motors.


boardmod.jpg
 
The revelation on the rpm has me rethinking my plan. I think I may reduce this back to 1 motor but figure out a way to lock the other tire in. Part of this upgrade was of course more power but also have 2 wheel drive.

Hardware stores and home Depot are open as is Walmart (gag). I bet I can find a resistor.
 
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