Electric rototiller conversion - Page 3

philb · 09-08-14, 12:42 AM

That tiller you have is a walk behind model, maybe Arens. The 5 HP gas engines I'm familiar with would spin the tines fast at 3600 RPM. 1800 RPM would probably do, but might be slow. Try one and see if it works. A fuse or breaker would be a good idea, just in case...
If you have an electric motor made for high torque applications, that would be ideal.

The rule of thumb is 1 electric HP = 2 1/2 gas HP.

jeff5may · 09-08-14, 08:18 PM

Quote:

Originally Posted by philb

The air compressor that I rewired had more starting torque at 240 VAC than it did at 120 VAC. I don't think it would be anymore efficient unless you are nearing locked rotor amps from burdening the motor down on 120 volts.

The losses in this rig will be mostly in the extension cord that supplies power to the motor. The power used by the cord is related to the square of the current that runs through it. The instantaneous cord losses at 240 Volts will be 1/4 the losses at 120 Volts throughout the range of normal operation. At high load, the losses will be even less, due to the cord not heating up and losing even less peak power.

If you've ever used a table saw, air compressor, arc welder, or other power hogging device on the end of an extension cord, you have probably noticed that the thing doesn't start up as easy after it has been running for awhile (if at all). If you've had lights running at the end of the cord with the device, you would have definitely noticed how much the light dims when you start the machine. Plenty of people have murdered their expensive power tools and blown fuse after fuse trying to run them on too long and/or thin of a cord.

This is the main reason why industrial power equipment is run at 480 Volts or higher. Due to the reduction in current draw, it is much safer and cheaper to run a step-down transformer near (or in) the load, and run much smaller wires between the source and the transformer. At the same load wattage, the source current is 4 times smaller, and the I^2 losses are 16 times smaller than at 120 Volts. So instead of pushing 20 Amps through the wires, they only need 5 Amps.

Daox · 10-17-14, 01:46 PM

Any updates on this project?

mechanic · 10-27-14, 10:09 PM

Haven't got back to it in awhile no

mechanic · 07-08-15, 08:14 PM

Since it's weeding season I finally got back to this. Pulled the tines off and mounted an 18" cultivator shovel (same width as tires) and a depth pad. Since this is just a weeding machine I thought this would be more efficient. It wouldn't dry the soil as much, shouldn't grab the plants with the tines, and should use less power. Well it ended up working much better! Motor went from growling and getting hot/stalling to idling along barely working. Doesn't pull in stringy plants like peas and doesn't fling dirt/bury leafy plants.

Daox · 08-11-15, 10:35 AM

Sounds like a nice upgrade. Thanks for sharing.

10-17-14, 01:46 PM	#23
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Any updates on this project? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-11-15, 10:35 AM	#26
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Sounds like a nice upgrade. Thanks for sharing. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-08-14, 12:42 AM	#21
philb Apprentice EcoRenovator Join Date: Nov 2010 Location: Oklahoma City Posts: 155 Thanks: 58 Thanked 17 Times in 14 Posts	That tiller you have is a walk behind model, maybe Arens. The 5 HP gas engines I'm familiar with would spin the tines fast at 3600 RPM. 1800 RPM would probably do, but might be slow. Try one and see if it works. A fuse or breaker would be a good idea, just in case... If you have an electric motor made for high torque applications, that would be ideal. The rule of thumb is 1 electric HP = 2 1/2 gas HP.

10-27-14, 10:09 PM	#24
mechanic Apprentice EcoRenovator Join Date: Aug 2014 Location: Saskatchewan, Canada Posts: 117 Thanks: 10 Thanked 16 Times in 12 Posts	Haven't got back to it in awhile no

07-08-15, 08:14 PM	#25
mechanic Apprentice EcoRenovator Join Date: Aug 2014 Location: Saskatchewan, Canada Posts: 117 Thanks: 10 Thanked 16 Times in 12 Posts	Since it's weeding season I finally got back to this. Pulled the tines off and mounted an 18" cultivator shovel (same width as tires) and a depth pad. Since this is just a weeding machine I thought this would be more efficient. It wouldn't dry the soil as much, shouldn't grab the plants with the tines, and should use less power. Well it ended up working much better! Motor went from growling and getting hot/stalling to idling along barely working. Doesn't pull in stringy plants like peas and doesn't fling dirt/bury leafy plants.