Let's make an electric mower.

[Wayne]

Thought I'd share some details on a project I am slowly plugging away at.

Long story short - I have a lot of lawn to mow here. Gas mowers kind of suck, great when they are working, but mine seem to need constant maintenance. One only has 200 hours on the hour meter. One day when both of my mowers died I said that's it, I'm converting one to electric.

Will it work? If it does work will it be reliable? Still some questionable hardware in use, so I doubt it will be very reliable. But think it will be quieter and wont suck down $20 in gas each mowing. Nope, this baby is going to solar powered. The payback should only be about 100 years!! LOL

Here is the mower, well, mowing:

The plan is pretty simple, remove the gas motor and install this big brushless motor in its place. Keep the rest of the mower more or less stock with belts and hydrostatic rear axle.

The motor is an Motenergy ME1206 and we are using our Sequre 200 amp PRO ESC. Yep hobby parts! Going by the specs we should be good with this ESC, but time will tell if heat will be an issue, it is a pretty tiny ESC for this large a motor. The Escape32 firmware allows us to fine tune the for the motor. Here it is in action:

Why this motor? Well, it should do the trick and found a used one for a fair price.

The rest of the setup is 48 volts of Eve 100 amp hour LiFe cells, a Victron 100/20 MPPT charger and some used solar panels. The ESC will be controlled by either a servo tester or maybe an Arduino. Only electronics on the mower will be the ESC and its controller. The rest will remain in the mower shed. No point in abusing the charger or possible inverter to mower abuse! (Did he say inverter? Yep, will be setup to plug in an inverter so it can double as a backup power source.

Have the basic parts collected.

Prepping the bigger mower for this swap, I managed to fix ALL of its issues! (Main issue was grass in a fuel line, that one had me stumped for a while.) I even fixed the smaller mower, this time it was some dead diodes buried in a wire harness and well, some other electrical issue that seems to have magically vanished. I'm sure it will come back. The bigger mower has 3 blades and a 54" deck. I'm converting that one as it is a better mower despite having 1400 hours. (I may run over to the dump and check the collection of old rider mowers they typically have, kind of a shame to pull apart a good running mower.)

The GT6000 is built much better than the newer mower, but has plenty of side projects for me to address while I have it pulled apart. The steering is in very sad condition.

For good measure here is the little mower when I was cleaning it up. Both units are Craftsmen branded but decently different despite the same basic layout and motors. Oh yeah, the big boy is also much faster.

 

[Red]

Dang......and here I thought I was opening a thread about a fun R/C gag plane

Cool conversion project though, looking forward to hearing how it goes.

 

[jure]

I have converted 140 A car alternators into BLDC 4 HP motors, very doable job.
Re-Wired it from delta to whye , to lower the Kv, reduce the max current , and increase the voltage specs.

The original idea was for a glider winch , or an electric kart.

Wayne , I still have the motor if you want it.
( I see that you have a fine one anyway ).

question: do you have a motor for propulsion and another for the mowing blades ?

 

[Wayne]

Sorry Red. The motor is sitting here in the shop, and when people visit it is fun to tell them that the motor is for our next glider project.

Jure - Nope, this is a single motor setup. I had debated swapping over to separate motors for everything. There are mower brushless motors that will accept blades, and I could convert my mower deck to take those, but in my research I found many folks complaining that those motors really don't do well in heavy grass, they will stall out. We do have heavy grass here, it is not a lawn, it is a pasture. To get around that limitation I could use a single larger motor for the deck, and I also debated that.

I had seen people doing single motor conversions using HUGE brushed motors and simple contactors. A little brutal, but works well. I liked the simplicity of this approach. Keeps most of the mower stock, so a lot less fabrication and head scratching. Simple is good. And honestly the belt drive on these mowers have not given me any trouble, so no great need to replace it. And if my mower blade nails a stump, the belt can slip. Built in clutching action.

So here is where I admit to not knowing any of the loads I need to feed. I'm wildly guessing at what the power requirements are for this project. I have almost no idea of how much power is actually going to be needed. I don't think the hydrostatic axle uses much power, yes, they are not efficient, but they are not the larger load. Spinning the 3 cutting blades in heavy grass is going to be the big load. I expect the torque of the electric motor will far exceed the gas motor.

My electric motor will be a little lower shaft RPM than the gas mower, so I may need to adjust pulley sizes to get the blade sweet to the sweet spot, but I often times do not cut at full throttle just to reduce noise and vibration and save a little fuel. I spend about $20 in gas per mow.

Found some new old stock solar panels for $25, might have to go grab those. I'm limited to 100 volts of panels with the solar charger I picked up.