Power Wheels EV

[redpoint5]

EDIT: TLDR build

Parts;

Ryobi Battery Adaptors x2 - $16
https://www.amazon.com/dp/B0C5QQHKG7...t_details&th=1
Power Connector - $9
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
18v Speed Controller - $26
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Throttle Pedal - $14
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Ignition Switch - $10
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

~$70 total to add a variable throttle, speed controller, Ryobi battery adaptors, and key ignition switch. Various tools, connectors, wire, solder, etc not included in the build inventory, as I already had these items.

Here's most of what I used in the build;


Here's the ignition switch, which fit perfectly without modification.


I've got a Jeep Wrangler EV now.

Considering a sealed lead acid battery is a poor choice for a traction battery since discharging them rapidly degrades capacity, I was keen to replace it with a lithium ion battery.

My garage has Ryobi 18v batteries aplenty since I'm a collector of those tools. I bought a cheap battery adaptor that adds leads and a fuse so I could attach it to other devices.

With just this modification, it adds 50% more power/speed. Max speed goes from 5 MPH up to 8 MPH.

The problem is, the plastic wheels have low grip and the throttle is on/off, meaning the thing spins the wheels and then takes off quickly, with no speed control at all.

I bought an 18v speed controller for $25, and a hall effect throttle pedal for $14.



Last night I finally got a round tuit. Decided to leave the original throttle pedal and mount the new one next to it. I used a shorter retention bolt in the stock pedal which keeps it "on" all the time. I swapped the top and bottom wires so that the original pedal is normally "on" and pressing it engages the brake. The floor plate was difficult for me to modify since there was no template that came with the throttle. It requires a hole in the middle because depressing the pedal extends it through the floor.



Wired 2x Ryobi adaptors in parallel using Wago connectors. The stock battery is 144 watt/hours (12v x 12 Ah). My batteries are 18v x 3 Ah each for 108 watt/hours. Not quite as much energy, but 1.5x the power. If I swap out for 4Ah Ryobi batteries, that would equal the energy of the stock battery. Ryobi makes all the way up to 12Ah, meaning I could potentially have up to 432 watt/hours, or 3x the stock range. Of course, you would never want to run a lead acid battery flat to get all of the range, so already it has more practical range.



Not factoring in the batteries, the project cost about $60 $70.



Here's a test of 18v speed prior to adding speed control

https://www.youtube.com/watch?v=TkYM7Et57AA

Maiden voyage this evening.

[freebeard]

Ditch the plastic wheels? With more power you can spin more rubber.

[redpoint5]

Originally Posted by freebeard

Ditch the plastic wheels? With more power you can spin more rubber.

That would be the next mod I'd be interested in. The plastic wheels is probably meant to preserve the gearbox since the stock throttle just punches hard. With a variable throttle, sticky tires can be used as power is eased in. The plastic is also noisy on pavement.

Maybe there's a coating or band or something I could put on the stock wheels? I could rivet an old bicycle tire to the plastic.

I had enough fun that I predict a custom built kart is in my future.

[freebeard]

This isn't much bigger than a kart.




Pictures taken in Glenwood, OR, in 2014. A golf cart axle and lead-acid batteries. Speedway will sell a roller chassis for 3200-5000.

https://www.speedwaymotors.com › shop › t-bucket-complete-kit-cars~65678-1-1877-135-612-30236
T-Bucket Complete Kit Cars | Speedway Motors
Speedway Motors | #7153400 Deluxe 1923 T-Bucket Frame Kit w/ Deluxe Body and Bed, No Floor as low as $3,782.99 /each Add to Cart

Or a body and frame from a swap meet for some fraction of that.

I'd want to section that body and lengthen it with center doors and sedan roof of aluminum.


https://car-from-uk.com/ebay/carphot...ebay724593.jpg

[redpoint5]

Originally Posted by freebeard

This isn't much bigger than a kart.

I've got an aluminum frame just waiting to be powered again.





Variable throttle successful. Grumpy driver. No mods for that.

https://www.youtube.com/watch?v=gBznYaI2OoQ

[Daox]

Looks like a great and fun project.

[Piotrsko]

Notes: Had sucess with pliobond and mostly worn out harley rear tire tread on tires. Son did manage to spin them off all after a while but his jeep was smoking fast.

You can get amazon batteries at 16ah if you don't mind knockoff chinesieum. Also cheap in hub motors from hipower scooters.

[redpoint5]

A few updates;

I blew a controller when I had my daughter go up a very steep grassy hill. Thought it was my fault, and ordered a replacement. Upon inspection, found one of the MOSFETS was not secured against the heatsink, but the replacement was constructed properly.

Found that the controller doesn't brake when letting off the throttle like the stock configuration. Kids went sailing down the hill.

Thought more on the original configuration and realized the single pole double throw (SPDT) pedal switch does 2 things. It normally has an open throttle (no throttle) and a closed brake (brake is on). In a DC motor, the brake is simply shorting the positive and negative terminals. Turning the motor causes a magnetic field that resists turning the motor.

I reversed the leads to the switch so that the motor is normally closed (on), and the brake is normally open (off). The 'on' motor is still regulated by the throttle, so it doesn't go unless the pedal is pushed. The idle consumption is 26 mA, which is why I added an ignition key.



All of this is to say, I turned the original throttle pedal into a brake. The nice thing is that pressing both at the same time still causes braking, because it opens (turns off) the throttle.

The 5 year old figured out the brake instantly, so no more uncontrolled descents down the hill.

Added an ignition key to turn the whole thing off, otherwise it consumes 26 mA at idle. The kid has been perfect operating the ignition so far.



Here's the next thing to mod, provided by my brother in law. I've got all the parts and the know-how. Throttle will be on the left side, and brake on the right, just because it's an engineering nightmare to put them where they belong. Kids will figure it out. After all, bicycles and motorcycles reverse the front brake levers, and I've never endo'ed either due to confusion, though the reversal is still stupid.