I'm new to the site and new to AC ownership.  I'm the co-founder of a small non-profit farm that serves people with and without disabilities http://www.commonrootsfarm.org" rel="nofollow - www.commonrootsfarm.org and the people who work here have been admiring the value of a G for a small acreage farm like this.  There is also some concern about the maintenance and environmental impact of another gas engine so since I work for an electric vehicle company and have access to parts and expertise we decided to convert one to electric. 

I got two non running Gs at auction and will start after the new year.  For now I'm trying to familiarize myself with the non engine parts of the tractors.

The plan is to make an adapter plate to replace the engine with an electric motor and install a battery pack where the engine is.  Since I'll be using lithium batteries, the pack will be small and fairly light, between 100 and 200 pounds depending on what's available for me to get from the rejected parts bin at work.

I'm thinking I'll need to turn down the performance of the electric motor to limit torque and acceleration so I don't wind up with 3 neutral gears.  Has anyone here done something like this?

Several people have made 'Green Gs' over the past 2-3 decades

The 'easy' route is to just use the motor and controller from a battery powered golf car.

The G has a 10HP engine, so a 5-7.5HP electric motor is a good 'fit'.

You'll have to reduce the motor RPM and increase torque, usually done with a double Vbelt setup rated for at least 10HP.

Your big issue will of course  be the lithium battery pack and BMS. You'll need to 'do the math' and see how large a battery pack you need for say 10 hrs of run time ( a typical farming day )

It is important that the motor and controller are 'matched', as in they WILL work together !

You can't just grab any old  motor and a 'looks OK' controller ,wire them up and expect them to work.

Regardless, welcome to the forum, and good luck with the project.  Oh, and we love pictures, lotsa pictures...

Thanks for the tip about matching the whole electric powertrain.  I'm an engineer for an EV company, and getting parts that are meant to be used together, so I think I'm OK there.

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I understand the point about not replacing something with lots of life in it for electric because of the payback time for all of the embodied energy in the electric.  My existing engine will go to replace an engine in someone else's G, not the scrapyard, so it won't be a total waste.  On a 3 acre farm with the G being used just as a cultivator, you are right.  From an energy saving point of view the payback in energy or money will be close to forever.  Part of the reason is the volunteers will have an easier time with something that doesn't need gas, or tuneups or having a carb gum up from non use for 6 months.  I'm in California, so nearly all of our electricity is from renewables, and the farm is installing lots of solar.

re: I'm in California, so nearly all of our electricity is from renewables

hmm, I was curious ...

and from the net...

 As of 2018, California had 80 GW of installed generation capacity encompassing more than 1,500 power plants; with 41 GW of natural gas, 26.5 GW of renewable (12 GW solar, 6 GW wind), 12 GW large hydroelectric, and 2.4 GW nuclear

so over HALF is NON renewable and no mention about the IMPORTED energy from other states which SHOULD be counted to be NONrenewable.

BTW there is a world of difference in an EV car power plant compared to a <10 HP EV tractor but it's pretty easy to figure out. 10 years ago when I had my 2nd G, I had planned on using a 10HP diesel to replace the worn out gas engine, then spent a month doing design/build for a 'battery G'. Mechanically it was easy and the controller dead simple,cost about $50 in components and about 500 lines of PIC C code

There's actually more 'tech' in the BMS needed for the battery recharger !

Thanks all for the interest and feedback.  I totally agree about the importance of the proper care and feeding of a battery pack.  I just spent a bunch of hours writing firmware drivers for battery monitor/balancing ICs so it's all pretty fresh in my mind.  I'm lucky in that our battery packs have that built in so if I can get my hands on a full pack that can't be sold as new for whatever reason I'll have a full plug and play setup.

I'm trying to decide which of my two tractors will be the runner and which the donor.  As far as I can tell from eyeballing them, both frames are straight.  One tractor has a bent tie rod.  Both have similar amount of slop in the steering.  I think that just means I should pick the better transmission.  I could remove the PTO cover and look for visible wear, and maybe get the wheels up and feel for slop, but I don't know if there is a better way.  One of them has a lot of dust stuck to the transaxle, which maybe indicates a leak.

Any ideas on how to pick the one to work on?

Thanks.

You should post pictures so we can see them.

I'd pull both engines and clutches, raise up off the ground, spin the input shafts and see/fee the gears. Almost all came with the ultra low 1st gear. I had 3, all 3 had it. When off the ground, you can check front end steering. decide which tires/rims are best. rear implement lift is nice, hydraulic front lift is nice, having good,straight tin makes them pretty ! One mod is to lengthen the frame for us normal height guys....

This is tractor 1.  The head is off the engine, and the fenders have a couple of tears I could weld and grind back to good condition.

This is Tractor 2.  Other than having a complete engine and radiator, which I won't need, I don't see a real difference.

And, of course, the water trough full of parts.  The sheetmetal is in there, along with other bits.