Battery Electric Stump Cutter

Greetings all!

 I bought a used stump cutter for my business and I'm trying to figure out if I

could go electric with it in the near future. It runs fine right now, so I thought
looking ahead would be a good idea since it is a 2001 model. If anyone has any
advice to offer I’d be very appreciative!

 The cutter is a Rayco RG20HD and it currently has a Kohler CH20 engine with

20.5HP (15.3 kW), 32.7 ft lbs (44.3 Nm) of torque and a hydrostatic drive system.
I really have no idea what kind of electric motor I should be considering. Weight is
important, of course. I think the Kohler, fuel tank and 12V battery weigh about 350
pounds so that’s about where I’d like to be for the weight. I think I could likely lower
the center of gravity with the batteries which means I could add another few pounds.
The machine feels more tippy than I like with that tall engine!

 Here's a link to Rayco's page about the newer version of my model, the RG25HD; It is all the same except the
new version has a more powerful engine.

 What I think would be awesome would be if I could use a hub motor for this.  I

just have no idea whether any would be at all able to handle the beating. On the other
hand it would be pretty nice to be able to just swap in a single motor and keep the same
belt drive system. I also wonder about replacing the hydrostatic drive with electric motors.

 Well, thanks in advance for any input!  I hope y'all are having a great start to

your weeks!



love to help with your problem but, I’m stumped…

I’m stumped…

Yes, you went there…

Ugh, lol. Anyway, it would be the first of it’s kind as far as I know.

Been thinking about this for a few days and I’m thinking this is not one of the pieces of yard equipment I would make electric. Stump grinding is hard on the motor, you need a lot of power behind it. I think the amperage draw would go through the roof. You’d haul a lot of batteries around for very little run time I suspect. Also, they hydrostatic drive absorbs the shock and impact from the cutter blade so it doesn’t break the motor, I would certainly keep that part if I were to try it on a lark.

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If you can get 100% efficiency. 20hp 14kw

Two of my $2500 batteries would give you an hour run time. Not too bad.
However I guess 30% is realistic. So 20 minutes, then charge overnight.

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When done grinding stumps for the day you can take it into the battlebots arena on the weekends.


Hey, aspca would not be amused. :wink:
Stumps are one thing, but…

I think like a lot of things stump grinding can be easier or harder on the motor depending on how people use and maintain them but that tremendously long belt drive should protect the motor pretty well. I keep mine running sharp and fast and never bog it down. Still, it would be a lot of current draw. Charging infrastructure is pretty good around here so I’d expect to build for fast charging if possible so I could just stop for a break in between jobs. I just don’t know much about what kind of motor would produce the power I’d need at 3600rpm max most efficiently. Then I could try to figure out how much battery I need and see how crazy the idea is. Even a solid 45 minutes of run time would take care of most jobs.

How much do those weigh?

120lb each. Electric motors are tough. Direct drive is most efficient, a belt drive maybe?
Here’s an idea.
Build a grinder using a 240v 3phase motor. Used motors are plentiful. Do your testing with a rented or used portable generator.
If deemed feasible, test it with an industrial vfd.
Last step is to power vfd from a full ev 350v battery. Voltage seems ideal for a 240v vfd.

Well, now that I looked up “VFD” and did some reading that makes sense. A quick check on motors like that and they are pretty heavy! About the same as the Kohler.

Yes, it will be much heavier and complex than ice engine.