M.L. Toys
M.L. Toys
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I want to go faster.
By jseabolt
I probably should have posted this first but if this device can't be used I have another use for it (cordless drill hooked to a car battery).

I've owned a 1980 Fiat Spider for 25 years and it's always had mediocre wipers. It's about like those vacuum operated wipers. I installed a Bosch wiper motor which works better than the original Marelli but it still was not to my liking. I ended up installing a 12 to 15 volt step up converter between the fusebox and column switch. WOW what a difference. Most likely I am not sending exactly 15 volts directly to the wiper motor but compensating for the voltage drop across the switches and connectors.


Image ... fbuq2i.mp4

So I got to thinking, could I install an 18 volt step up converter between the battery and wiring harness on my daughter's Kid Trax instead of going with the 12 + 6 volt battery method?

Anybody ever done this?

I realize that this is going to pull more current and the battery is going to run down quicker. But if it works then I could possibly find a battery with more than 12 aH. Or maybe add a second 12 volt battery and wire them in parallel. If I can fit one under the seat.

It hasn't arrived yet being shipped here from China.

Image ... EBIDX%3AIT

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My fear is you will blow it up. I've seen one of my err.... my kiddo's rides pull 20-25 amps on startup. I'm sure they clear 30A on a grassy uphill ascent. I run 40A fuses.

Listing says it's a 10A unit. I see smoke in your future. All depends on how you're set up I guess.
By jseabolt
I did not know those motors pulled that many amps.

My daughter's Yamaha Raptor ATV does have a 40 amp fuse. The Kid Trax VW is not fused (or have not seen one) so I probably need to add one to just to sure.

I was going to get one of these 12 to 18 volt converters anyway to power an old cordless drill off my car's battery. So I may just end up using it for that purpose.
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By Hammer-fm
Ok, this thread is a bit old but this was a question I had too when I first started modding, and maybe someone else will have the same question.

I recommend against this. I purchased a 30A DC-DC boost converter on ebay and it worked fine on my son's Hurricane for awhile, but eventually (with a larger driver) it blew up on initial startup. (look up "1500W 30A DC-DC Boost Converter"). This is a pretty beefy converter.

The problem is that standard step-up converters fundamentally can't limit current, and won't allow the output to go below the input voltage. If the output pulls too much, it simply pulls it all through the inductor and the resulting current load can destroy the mosfet switch when it tries to ground the far end of the inductor.

The motors don't pull "30A" at startup. For the most common Power Wheels motors, the stall current is 60A *each* at 12V, so even with wiring losses, it's likely pulling an instantaneous 70A-80A if you are in 2nd gear (motors in parallel) and just hit the gas. It will quickly drop to a more reasonable amount as the motor speed comes up.

Mine lasted as long as it did (1 month)because it had a 150A-rated MOSFET and was generally run on low-traction surfaces -- it died when it had a 60lb load high-traction conditions.

Standard slow-blow fuses and breakers are often specified to allow 200% current for several minutes before blowing, so the fact that the batteries have a 30 or 40A breaker shouldn't be taken as a maximum current value (whereas the drive transistors and other components in a step-up converter could be damaged in a period of 10s of microseconds, depending on the scenario).

Alternative: I did use a step-down converter, combined with 24V battery (pair, in series). With a step-down converter you can limit current and they're pretty much bulletproof. The downside is that you'll need two 12V batteries, and you need to do some wiring. I set mine up with a knob near the steering wheel that would allow the kids to select the output voltage from 6-22V. The ones I got were $4/ea from China -- look for something like:

"Buck Converter Step-down Power Module 7-32V to 0.8-28V 12A"

on ebay. You can parallel them if you connect the vref return pins together of the boards (the Hurricane has 4 boards installed, pushing up to 50A). However, it is likely easier to just purchase a motor controller board instead.

Step-up converter installed (I don't have a picture of the step-down array):
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