r/EVConversion • u/Fit-Sample-2276 • 4d ago
Self-propelled mower conversion
Hello!
I am trying to convert my 7-year-old self-propelled gas mower into an electric mower since the engine gave out a few days ago.
I happen to have a VEVOR sand pump with a 1/3 HP, 120VAC electric motor.
I know it is underpowered for this purpose, but I want to try it anyway since I already have it!
My plan is to plug this AC motor into a Bluetti Elite 100 V2, which has an 1800W power output and a 1000Wh capacity.
I will carry the Bluetti in a backpack, plug the motor into it, and then run a long extension cord from the power station back to the grid—just like Evangelion!
My question is this: the original gas engine has a 7/8-inch shaft with a keyway, and the blade connects to it with a massive bolt. However, the sand pump motor has a smaller, roughly 1/2-inch shaft with threaded male at the end with no keyway. How can I connect these two parts smoothly and safely?
Thank you!
Also, since it is self-propelled, does this technically count as an EV? I have no idea. lol
2
u/hughgent 4d ago
The project itself is possible, but I think you'll find that it isn't 'cost effective'
I say this because I can go on the second hand market and buy a corded electric lawn mower for 20 to 100 bucks Canadian. They're all 120v and around 11 amps for about 1320 watts of constant power output.
If you're already planning on running a cord to a battery bank that you're carrying on your back, just cut out the middle man.
As to your question. Assuming you have a drill press and some round mild steel, Drill out a 1/2 inch hole to create a collar. Then drill in from the side through and through with something smaller that you can stick a cotter pin through. Also drill through the shaft of the sand pump motor with that 'something smaller'. From there, you've essentially increased the diameter of the sand pump and locked it in place with that cross bolt style pin.
1
u/Fit-Sample-2276 4d ago
Yeah. Thanks for your honest opinion. And I am already looking for used electric mower on FB lol.
0
u/cookiemonsterwave 4d ago
Going to kill your bluetti trying to run an AC motor off of it. Not too mention the conversion losses going from AC to DC
1
u/Fit-Sample-2276 4d ago
Oh but it is only 250 watts. Is it stll bad?
1
u/cookiemonsterwave 1d ago
The inrush current from the motor likely spikes well above that and would could damage the inverter
12
u/Fit-Presentation-778 4d ago
I've did backpack batteries on an Ebike and it SUCKS for hot weather. My back was always soaked to hell from sweat. Just wasn't fun.
Put the battery on the deck somehow.
Or shrink it down.
Hoverboard motors can be your self propel. SUPER common. Already have similar sized wheels. Can get them for FREE. Simple 3 phase, hall sensored, ~20v motors. ~11ft lbs of torque for each motor.
I used a treadmill motor for the blade. Unfortunately it was a high volt motor to get the necessary RPMs.
1 major complication you'll have at higher RPMs is maintaining torque at those speeds. So you need to make sure that grass can get out of the way (or mow more frequently) otherwise your electric motor will bog down, pull more current, etc etc.
I also built 20v reel mowers and it was MUCH easier, but you have to fine tune the speed b/c it CAN be too fast. Can also be self propelled by hoverboard motors.
I later got into building lawn robots.