Cheap 48V Pocket Mod Scooter

Time to start documenting a few EV projects sitting in my garage. I'll start with this one:

The goal was to build an easy, cheap, electric pit bike (mission accomplished). Last year I picked up a non-running Razor Pocket Mod scooter of CL for about $20 (Or was it free? Who can remember). For reference: https://www.razor.com/products/ride-ons/pocket-mod/

Around the same time I found someone selling a Craftsman 48V lawnmower for something like $50. http://www.searsoutlet.com/48V-19-P...er/d/product_details.jsp?pid=1632&mode=seeAll Side note, I recommend keeping an eye out for these mowers; If you can fetch one for less than $50 and don't care too much about weight, the motors are pretty nice. Also I'm thinking they can handle over 48V. (more on that later)

I think you can see where this is going. To finish the job I picked up a cheap, Chinese 1500W brushed motor controller with throttle, off Amazon. It took about 8 hours one weekend to transplant the motor and old lead acid batteries into the scooter chassis. The goal was cheap, easy to build and functional, so I welded and cut pretty recklessly... Including welding the old 250W motor's tiny sprocket directly to the huge output shaft of the Craftsman's motor. I also added some some foot rests that function as kick stands, and some crash bars for the motor, since it hangs so far outside the little scooter's frame.

Couldn't reuse any of the body panels, but the wheels, tires, chain & tensioner, brake (rear only) and seat, where all re-used. The batteries, motor charge indicator and charger all came from the mower. I firmly believe all EVs should be capable of smokey burn outs, so It's geared more for torque than top speed. Range is about, 15 trips around the block? I don't have many pictures from the build because I was moving fast and loose, but these videos show the performance pretty well.

Overview and sick burnout: https://youtu.be/zyRVEe_1QmY

(Warning: vertical videos)

Cruising the streets: https://youtu.be/NVWeNKxGTTk

Crash Guards: https://youtu.be/AN0LEF7aMQc

Next Up: Upgrades!

After a winter of neglect, one of the four original 7AHr lead acid batteries had lost a cell and little scooter was only good for a couple trips up and down the street. I started thinking about building my own lithium pack, but didn't want to put too much money into a $100 project. It happened I knew someone with a few leftover Headway cells http://www.headway-headquarters.com/38120s-10ah-headway-energy-cell/ from his own project, and I convinced him to gift me the left overs. I managed to find 16 that where stable and undamaged, so that was the base for a new 48V, 10Ahr pack, which is actually total overkill for the vehicle.

Cells, re-shrink wrapped, sorted, balanced manually

I bought some Headway bus bars and cell holders

I wasn't going to drop money on a BMS, knowing I could manual check cell balance periodically, but I wanted to know the pack voltage and see what kind of power the little scooter was actually pulling, so I invested in a watt meter. Also, knowing that the scooter would be bounced around and subject to plenty of abuse, I needed a cheap and easy battery box. Turns out I had some old shelves laying around...

Battery box with fuse, disconnect and power meter. This way it can be dropped into a different project if need be, has proper connectors, plus I have a 24V UPS that might need a battery upgrade some day...

So much for foot space...

The poor old Razor was only rated for 170lbs out of the box, which is a little less than my own weight, and I had added about 30lbs of parts. Chassis flex was always a problem, but now the battery box was now the directly in the path of compression. I decided I needed to reinforce the chassis, which meant abandoning the old seat. The new, lower seating position actually felt more "pit bikey" even though it was un-padded. Plus I lost the storage area for the charger :-/

Sizing new parts

Found some seat pan material



End result, peak current draw is 36A, peak power (out of the batteries) 1850Watts. Next up: MORE upgrades!

Third and final chapter:

Now that the Razor scooter had a battery worth 4x the rest of the bike, I figured why stop the insanity? I had a bunch of LEDs laying around and an old 48V to 12V converter. For the headlight I added a heatsink, some lenses and a little water-proofing epoxy. I had lenses to focus the light but wanted to add a hood so I'd be less likely to blind anyone looking directly at the beast. I also dropped a string of red LEDs on the back, to complete the look.

I also repaired a bent foot rest that happened when one of my less sophisticated associated rode the poor scooter directly off the closest curb.

View attachment 2 The headlight bracket, like the rest of the bike, was made hastily and from scrap

View attachment 1 Need to move the heat

Complete the look

Finally, a video of the new illumination, in action:
https://youtu.be/zFLW2E4vI50

I think this project is finally complete. Hasn't seen much action because it gets a lot of side ways looks from neighbors and I haven't been bold enough to go beyond my block. Its a great little bike for the paddock or camp ground, but also not exactly lightweight. Still have less than $200 into it, not counting the parts I already had sitting around. I'm curious how much power this motor would draw if I bypassed the 1500Watt controller with a straight switch, but not curious enough to tear apart the wiring once again.

Sorry I couldn't help.
I like your materials sourcing methods.

Robot_Exterminator said:

Also I'm thinking they can handle over 48V. (more on that later)

Click to expand...

THey can, but the higher the voltag eyou put thru the commutator, the worse the arcing is and the faster the brushes burn up/wear out, and the hotter the motor gets.

ALso they will have a maximum design RPM, and exceeding that could cause the commutator to "grenade", which is not a happy experience.

Some stuff about it
https://www.google.com/search?q=commutator+to+%22grenade%22%2C&ie=utf-8&oe=utf-8#q=brushed+motor+commutator+grenade*

amberwolf said:

ALso they will have a maximum design RPM, and exceeding that could cause the commutator to "grenade", which is not a happy experience.

Click to expand...

My new pack runs up to about 54V but I'd like someday to see how the motor runs around 60. Looking at the motor and seeing how over-sized it is, even for the mower, I'm thinking Craftsman found a supplier that already had a part on the shelf. (The brushes on mine looked brand new, but the wires were pretty dainty). My gut tells me it was designed for a higher power application. Either way, people basically give these things away when the batteries die, so I'm not too worried about preserving the motor.

Sorry I couldn't help.
I doubt it would have problems with only 60v; that's about what a fully charged 4-SLA system would be anyway (maybe only about 56-58; possibly a lot less under load due to voltage sag if the SLA are not of sufficient size for the required current).

It's when you get into double and up of the design voltage.

Many motors have a nameplate on them to tell you what it was made to work with; voltage, RPM, type, etc. Does that one?



As to it's size, well, it actually takes a fair bit of power to do mowing. Ther'es a thread about electric lawnmowing and such, recently posted to by me if you look thru my posts, where someone has posted the power usages for at least one particular mower.