Electric Tractor Conversion - Allis G Cultivator

The Allis model G is an excellent little cultivator tractor that is popular with small-scale truck farms. Manufactured from 1948 to 1955, there were almost 30,000 of them made. While most small tractors such as the venerable Ford 8N have the engine block as an integral part of the tractor structural frame, the Allis G was almost unique in that the engine was rear-mounted, and not part of the frame. This means that the engine can be removed and replaced by an electric motor rather easily. Photo above shows an Allis G complete, and one with the engine and cultivating implements removed.

Here is a video of the finished project

So many of these tractors have been converted to electric, that a small machine shop actually has a kit for some of the critical mechanical parts. Niekamp Tool Company, 845-338-7959 still sells the mechanical parts in the conversion kit. They say they have sold several hundred of them. Their contact information is in the materials section below. There was a small farm called "Flying Beet" that published an instruction sheet through a USDA SARE grant. FlyingBeet is no more, the document can only be found on archive.org these days. Many of the suppliers they listed are now out of business.

These useful instructions Flying Beet are becoming dated. The original conversions used lead-acid batteries, and the batteries had a number of problems. The motors they used are out of stock now, the controllers they used are not made any more and other issues. In this Instructible we will update the Allis G Electric Conversion to modern specs.

This Instructable isn't for everyone - you are constructing an electric vehicle almost from scratch. You might need to be somewhat familiar with basic low voltage electricity, handy with wrenches, and will need to fabricate a few items like a waterproof battery box. You may be following along trying to convert a different vehicle, such as a lawnmower or a different style of tractor. This same kit of parts would convert almost any machine that you can adapt the motor shaft to.

DONOR TRACTOR

You'll be looking for an Allis G in good working order as far as the transmission and other mechanical parts are concerned. If the motor runs at all, that's great although it may cost you more than a unit with a siezed motor. Without a working motor it may be difficult to test the transmission and other functions, try to ascertain if the transmission has caused any problems (hopefully you are buying from an honest and forthright seller) It will be an asset if the tires are in good shape. We had issues with a bad transmission that caused us a little trouble until we found a spare Allis G to cannibalize. Any implements that come with it are an asset, these can include belly mowers, various tilling implements, disks, seeders and so on.

ELECTRIC MOTOR

The FlyingBeet instructions specified a motor from Advanced Motors and Drives model A00-4009. This motor is no longer available. It was used on several golf carts and electric carry-alls and this model can sometimes still be found on ebay and industrial surplus. We found one on Ebay, however the supply of these older motors is dwindling.

Many similar motors are available. Make sure you are getting a 36/48V DC motor, about 4.25 HP, 56C frame, 2800 RPM with a 7/8" diameter keyed shaft. Many used forklift motors will come close, however the shaft will be different and that will cause some headaches.

Vintage Golf Carts lists several drop-in replacement motors:

Motors for the following golf carts and carry-alls: Advanced 24/36/48 Volt Motor for Motrec. Also 1992 and newer Nordskog Legend / US Electicar Carry All and Payloader models B, C and D from serial number 280A92HO09 and newer. Also Legend model 325 B & C Tote'N Tow. Motor model A89-4001 used in some earlier carts.

Any of the series-would DC motors that Vintage Golf Carts sell for the Motrex cart should work; MT70-700, MT70-730, MT70-720,

Vintage Golf Carts also sells replacement brushes for these motors, and you should pick up a set now while they are still available.

M&M Forklift Motor Repair sells a used Advanced Motor And Drives DD0-4002 which appears to be a drop in replacement. Other forklift repair companies may be local to you and might be able to source this motor.

Prices in 2023 are running about $1200 for these motors.

Hardware Kit

It is best to obtain a mechanical adapter kit from Niekamp Tool Company, 845-338-7959 https://www.niekampinc.com/

719 State Route 28, Kingston, NY 12401, USA. They still have the plans, but have to start machining the adapter kit when they get an order. One could consider machining an adapter kit if this becomes unavailable, but that would be a whole 'nuther project as they say. Neikamp says they have built hundreds of these kits. Ours took about three months from order to delivery, as some of the materials they needed were backordered.

Batteries

The original Flying Beet conversion used lead acid batteries. Lead acid batteries are simple, been around a long time, but don't last, and don't have the power to run the tractor a long time without stacking on a large weight of them. Modern electric vehicles use Lithium batteries, and we recommend this is what you use. Flying Beet and other users complained they did not get enough power out of the Lead acid batts.

Lithium batteries come in two flavors - Lithium Ion batteries, like the ones used in Teslas and other electric cars, and Lithium Iron Phosphate. Lithium Iron Phosphate is a far safer chemistry than Lithium Ion, which can famously cause fires. Lithium Iron Phosphate batteries won't cause a fire even when punctured or abused, and believe me I've taken one out in the middle of a large gravel lot and attempted to make them blow. I'm kind of easily amused you know. The worst they will do is emit a nasty cloud of gas if punctured or overcharged, nothing you want to breathe but there is no risk of burning down anyone's barn. Lithium Iron Phosphate batteries are heavier than Lithium Ion, but about half the weight of Lead Acid batteries.

A Lead acid battery is a simple stack of cells. Charge it up, and it moves electrons around. But a Lithium battery always includes electronics. A Battery Management System (BMS) built into them protects the battery from overcharge, overdischarge, or operating at too high or too low a temperature.

We used a Pionergy 200 Amp Hour, Lithium Iron Phosphate 12V battery as the basis for our battery pack, four of these provide a 48V battery pack, the maximum voltage the manufacturer recommends. There are many positive reviews of their products on carious electric vehicle forums. Pionergy maintains a store on Ebay called Pionergy_Direct, https://www.ebay.com/str/inforbattery which is the easiest place to find US distribution. If there is no stock in the ebay store just this minute, message them and they will put something up there. They are also available on Amazon. Several other brands of similar batteries are available, for example Dakota Lithium.

Lithium batteries do not function well at cold temperatures. The Pionergy battery cuts off below 0C(32F) and above 45C(113F), not allowing charge or use outside those ranges. Our farmer assures us she's not likely to be doing much cultivating below freezing and will come inside if it is 113F outside. The batteries should not be in direct sun which could elevate their temperature. We will build a box to protect them from sun and banging around, which will be ventilated to keep it cooler. The battery box will also contain some electronics.

There are many other manufacturers of 12V Lithium Iron Phosphate batteries, make sure you find one that is 200 Amp Hours, Lithium Iron Phosphate (not Lithium Ion), Capable of stacking into a 48V configuration, includes BMS electronics, and has reputable reviews.

A word about battery safety. This represents a serious amount of energy, and an arc from connecting such a battery wrong could blow up the wires or the terminals. An arc can happen if you complete a circuit while it is turned on, or short a plus and minus battery terminal together with a wire or loose tool. Avoid bare terminals, work on only one bare terminal at a time lest a stray wire or screwdriver short across a plus and minus. Insulate any bare terminals you are not currently working on, like the other end of the wire, with some electrical tape. Connect the end of the wire on the battery first, connect the other end to any load second. (if the wire is terminated a the battery last, it may create a n arc which will destroy the battery terminal, ruining the battery.) High Current Arcs are a serious risk, basically like starting up an arc welder. Wear safety glasses when doing live wiring, use insulated tools, follow the rule of only one bare terminal at a time.

Protect yourself against some other hazards: Uncontrolled operation (tractor takes off when you are wiring it up) make sure the tractor is up on blocks and wheels can free spin when you are wiring things up, or the motor is disconnected from power.

Plan to permanently insulate all battery connections with (ideally) heat shrink tubing or (not as good) electrical tape or painted-on electrical terminal liquid. Never leave any bare permanent terminals or wire ends - they invite a hazard later on. The first item past the battery should be a fuse, the next a contactor, then the motor controller. 48 volts is not a lot of voltage (electrical pressure) and is not as dangerous as 120V AC, however it is more hazardous than 12 volts typically found in a car and can produce a painful shock.

We could have designed for 60 or 72 volts, which would give us more power, by adding one or two more batteries. 48 volts is a nice system voltage in that it is not as hazardous for shock potential, there are a number of common golf cart components that work with it, our particular battery manufacturer recommends systems with no more than 48 volts (their electronics are not designed for higher voltage systems), and 48 volts is "good enough". The motor we use is rated for 36 or 48 volts, but can be operated at higher voltages for more power (with more risk of frying it.)

Charger

Not gonna roll up to a Tesla Charging Station with this rig! We will build a special charging station that will create 58.4 volts (the required charging voltage) with a controlled current. Mean Well is a well known company that makes reliable DC power supplies. I have been using them as Ebike chargers for years. There are several configurations that could be used. We used (2) Mean Well LRS-450-12 12V DC Power Supplies, a Mean Well SE-450-12 and a SE-450-15 15V power supply to make up the total of 58.4 volts needed for a full charge. There are other ways to charge, using a stack of Mean Well LRS-350-12 and LRS-350-15 power supplies for example, but the '15s are out of stock right now, and the 450 watt power supplies will charge faster. All of these supplies are adjustable, and we will set them up later so that we can't overcharge the batteries. The charger will be in a non-waterproof case that we will plug in inside our barn. We will run it on a 240V outlet (the same one our welder usually shares). It will charge at 30 amps which will charge up the system in about 7 hours. A quick charge over a 2 hour lunch break would put back about 30% of the battery's capacity.

One could set up several smaller mean-well power supplies and run them safely on 120VAC. For example a Mean Well LRS-350-36 plus a LRS-350-24 would be a 36 volts and a 24 volt supply, which can be adjusted within their ranges to make 58 volts 10 amps. This would charge back up in about 20 hours.

Never charge Lithium batteries below freezing. We will place a sign on the charger to warn users. The electronics int he batteries may prevent them from charging at cold temperatures, however we don't want to take any chance of ruining the batteries. Bring the batteries to a non-freezing area when it is consistently cold - extreme cold temperatures are bad for them.

Some Other Considerations:

It is possible to set these motors up so they can electrically reverse, but we just used the tractor's transmission for that function. The clutch is still in place but one can just stop the motor, shift to neutral, rev it a bit and slip the tranny into the new gear as it is winding down. This is called "double clutch" technique and was needed on some really old trucks, or any manual vehicle when the clutch goes out.

Batteries need to be taken inside away from freezing conditions in the winter for maximum life. Charge them up, disconnect the Anderson plugs, lift them one by one out of the battery box and bring them inside. We elected to do this instead of the potential complexity of keeping them warm with a heater. Our farmer assures us that she's only using this tractor in above freezing conditions. We will put a sign in English and Spanish on the battery box stating the batteries must be taken inside for winter storage.

We elected not to install lights. No tail-light either, this tractor is never going on a road.

Some of these tractors have a hydraulic implement lift, which would require a 12V DC hydraulic pump and a bunch of other complications. Our tractors are manual lift and that seems to be just fine.

Full List of Supplies:

Donor Tractor:

Allis G in decent condition with a working transmission. $1500 - $5000

Motor:

A DC motor with a 36/48V DC motor, series wound armature and field, about 4.25 HP at 48 volts, 56C frame, 2800 RPM with a 7/8" diameter keyed shaft. The following motors (and probably many more) can meet this spec:

• Advanced Motors and Drives model A00-4009
• Any of the series-would DC motors that Vintage Golf Carts sell for the Motrex golf cart ; MT70-700, MT70-730, MT70-720,
• Motors for 1992 and newer Nordskog Legend / US Electicar Carry All and Payloader models B, C and D from serial number 280A92HO09 and newer
• Legend model 325 B & C Tote'N Tow. Motor model A89-4001
• Advanced Motor And Drives DD0-4002

Many of these motors might be found at used, rebuilt or surplus outlets, or on ebay. Call your local forklift, motor rebuilder or golf cart supplier if you have one locally - most towns have one lurking in a sleepy industrial backstreet - it is highly likely they can source one of these motors or something that will work. We see these motors going for about $1200 as this manuscript is published.

Batteries

(4) 12 volt batteries of at least 200 Amp Hour capacity, Lithium Iron Phosphate chemistry, with built-in internal battery management electronics. Pionergy, Dakota Lithium, and many others can supply these types of batteries these days. We paid about $2000 for a set of 4 batteries.

Motor Controller

Curtis 1205M DC motor controller set up for 5Kohm throttle pot, 48V system. These units are software programmable for various parameters, make sure yours is set up like this or that the place you get it from can change these parameters. Many golf cart suppliers use this controller and can set them up with a custom programmer. $375 on Ebay.

Balance of System:

• Heavy duty waterproof (IP65) toggle switch for an on-off switch. We just ordered an IP-65 (that means waterproof) toggle switch on ebay. We could have used a key switch, either one would work.
• Battery Capacity Indicator (Ours was a Supnova Battery Monitor but there are a number of brands of similar items available on ebay.) Measuring range 0-100V, capable of measuring 12V, 24V, 36V, 48V or 72V batteries, can be set up for Lithium batteries, displays battery charge percentage. Specifically capable of measuring Lithium Iron Phosphate batteries. $12.35 plus shipping on Ebay last we checked.
• 48V, 400A main contactor/solenoid. We used OE Part Number: MZJ-400, from GolfPartStore on ebay
• Throttle, 0-5K Foot Throttle EV Potentiometer, similar to Curtis FP-6. This unit is in a sturdy metal case with a tight plastic lid and a foot pedal. It appears to be mostly watertight but we will put it inside the battery box for protection. It looks more robust than the Curtis PB-6 style throttle pots. About $60-$75 on ebay.
• Charger: we used (2) Mean Well LRS-450-12 DC Power Supplies and (2) Mean Well LRS-450-15 power supplies to make up the total of 58.4 volts needed for a full charge. There are other ways to charge, using a stack of Mean Well LRS-350-12 and LRS-350-15 power supplies for example, but the 350-15s are out of stock right now, and the 450 watt power supplies will charge faster. We had about $130 in these four power supplies. Ebay, Mouser.com, Jameco Electronics or Digikey sells these.
• Power Connectors - we used two red Anderson SG175 battery quick connectors with 1/0 terminals, and (12) grey Anderson SG175 battery quick connectors with #2 terminals. The Anderson system does not allow connectors of different colors to connect together, making it more difficult for someone to hook things up wrong. Red connections are for charging, Grey connections are for battery disconnect. These go for $7 to $12 each, look for a bulk deal. We had about $100 in battery quick connectors.
• Battery Cable - we went to an auto parts store and ordered about 12 feet of #2 battery cable, plus about 10 feet of #1/0 battery cable. Welding cable would also work, in the same sizes. House wiring cable is too stiff and won't be easy to work with.
• 1/2", 3/4", and 1" diameter heat shrink tubing. We bought a couple of packs of this stuff at Harbor Freight. You can also find it at electrical wholesalers. Don't buy little 6" pieces in the hardware store you'll go broke before you've insulated all the connections.
• 5/16" diameter #2 copper terminals - I think we used at least 16 heavy terminals. Bought them at a farm supply store and an auto parts store.
• Plywood, 3/4", about three fourths of a sheet
• Steel angle iron, 1-1/2"X1-1/2", about fifteen feet.
• Galvanized sheet metal for waterproofing the lid of the battery box
• Paint for the battery box. We used a waterproof roof paint called Elastomeric Roof Coating, but really any good paint will help keep water out of the sides of the battery box.
• Silicon or other good caulk for sealing the battery box.
• Fan TBD for helping to cool the electronics
• Screen wire to keep Mud Dobber wasps out of the battery box but allow airflow. These little devils will ruin any machinery they build a nest in.
• 2" deck screws and 1/4-20 carriage bolts for assembling the battery box. Various sizes of other 1/4-20 bolts and nuts were used for mounting components and assemblies. We like to keep 1/4-20 stainless steel bolts and nuts in stock as they never rust, but stainless is not an absolute requirement.
• Mechanical adapter kit from Niekamp Tool Company, 845-338-7959 https://www.niekampinc.com/719 State Route 28, Kingston, NY 12401, USA.
• Paint for the tractor. We used Rustoleum tractor and implement paint, an alkyd enamel from Tractor Supply. We bought a couple of gallons and painted some of the other implements and tractors at the same time. About $66 per gallon
• ANL 400A 80V Fuse (Victron Part Number CIP142400000 available from Northern Arizona Wind and Sun: Solar-Electric.com or Mouser $11
• ANL Fuseholder (Victron Part Number CIP106100000) also available from Solar-Electric.com or Mouser $11
• Littlefuse brand FKS ATO fuse rated for 80V DC (NOT an automotive fuse it just looks like one) Part number 166.7000.525 available from Mouser.com
• Littelfuse ATO Fuseholder Part No 913-008 available from Mouser.com
• Littelfuse Mega 80A fuse rated for 70V DC Part Number 0998080.UX-2M8 available from Mouser.com $13.05
• We could buy a $15 fuseholder for this, but honestly it's a piece of plastic with two bolts, we just bolted the fuse between two wire terminals and heat shrinked it.
• LED panelmount indicator - Indicates 48V DC Bivar brand part no PM5-PRRDW12.0 available from Mouser.com
• Curtis Controller Status LED - indicates any trouble at the controller - We just used an LED and a 1K resistor glued into a hole in the battery case, but to get an official-looking panel indicator you might try Bivar Part Number PM3-PPGDW48.0 available from Mouser.com
• Insulating terminal covers. We used liquid insulation compound from the electrical section of the ghardware store. We considered 3D printing some terminal covers, this is a great idea if you have access to a 3D printer.

At the time of this writing in 2023 we have about $4000 in this kit of parts.

Special Tools

We bought a hydraulic crimper from Harbor Freight for $69. It is very difficult to make proper connections to large gauge wire without such a crimper, and your old crimping pliers are definitely not up to the task. We already had a plasma cutter, which is handy for cutting out steel quickly. As we used some old scrap bedframes for angle iron, these sometimes have quite surprisingly hard steel which will ruin good drill bits fast. In order to fasten to these free scraps we zapped some holes for bolts with the plasma cutter. I'd suggest using new mild steel to begin with as most people don't have access to such a tool. We used some welds on the steel frame for the battery box, absolutely optional as bolted connections would be fine here.

Heat gun to shrink the heat shrink tubing.

We used a volt-ohm-ammeter to check and troubleshoot things, all through the project.

Other than that, we used a MIG welder to attach some parts and build a frame to support the battery box, and various other standard hand tools and battery drills.

There are probably thousands of Allis G tractors in existence, originally there were about 30,000 made. They can be found for 2024 prices ranging from $1000 to $5000. You'll be removing the motor and gas tank from the rear of the tractor. It is heavy, topping 100 LBS, you will need two or three people or an engine lift. Retain the clutch and keep any bolts handy in case they are needed for reassembly.

Now is the time to consider cleaning and painting the tractor. We do not know if the original paint was lead-based, however lead based paint was common in this era and we should assume there is lead paint on the tractor. Wash it down with a powerful pressure washer to remove any grime and flaking paint. This is safer than other methods as it produces no dust. It is best to do any paint removal over a large tarp or concrete pad, try to collect as much of the paint chips as possible and avoid contaminating your land.

If you are removing old paint with a sandblaster or other methods, wear an N95 dust mask and assume your clothes are contaminated - a throwaway painting coverall is a good idea. Shop vac any paint chips with a good filter on the shop vac and using an N95 mask. Once you have collected any paint chips, bag them up and dispose of them properly.

Any non-electrical parts that are to be reused have to be in good working order. Consider replacing a full set of tires, using fluid to increase the weight and help in preventing wheelies (this is very dangerous, never allow a tractor to pop a wheelie, they can flip over and kill you.) Decide if you are going to use any lighting (most farm tractors that never go on public roads do not need lights for safety, many people don't use lights for operation on their tractors, just working in daylight.) And decide if you are going to use hydraulics to lift the implements. One of our projects (we are working on two tractors) uses 12V hydraulics, the other uses a manual lift.

Remove any implements to facilitate construction, paint them, and reinstall them later.

Remove the motor. Remove the clutch assembly and SAVE THE CLUTCH DISK. This will be used to interface the new electric motor to the old shaft.

You can optionally remove the clutch foot lever, clutch arm and throwout bearing as they will not be used.

Remove other extraneous parts such as the 12V battery box. Some tractors have a power take-off pulley, dangerous as a badger in a puppy truck, be sure to remove this before it catches someone's overalls and wraps them up.

Most everything on the tractor will be rusty and greasy. Use penetrating oil on various bolts, turn them out to remove them partially, lubricate them and re-install them. Consider renting a sandblaster to remove rust and old paint. Replace any broken or worn-out parts that are to be re-used. Degrease the tractor with an appropriate solvent before painting - there are a number of commercial degreasing solutions that are available by the gallon in painting stores or better hardware outlets. Apply with a clean rag, let them soak for for a short period. Replace rags frequently as you wipe off the solvent, to prevent a dirty rag from spreading more grease. Clean with water or soap and water to remove the solvent.

Paint the tractor with a good quality tractor paint from a farm implement store. Consider spray painting it for better quality.

We decided on a 3/4" plywood box, with a steel frame supporting it. We'll waterproof the box with a coating (optionally just paint it), seal the corners inside, and cover the lid with galvanized sheet metal to keep the rain out. The box will have ventilation on the bottom side. All wires exit the bottom to keep things raintight.

The steel frame (made of angle iron) is designed to fit snugly on the bottom of the wooden battery box. It attaches to the tractor at three points - two "tabs" that come up from the axles, and one angle iron piece that we welded on just at the very rear of the top of the transmission housing. The steel frame is bolted at all these connections to facilitate later removal, with 1/4-20 bolts and lock washers.

The battery box is covered by a sturdy 3/4" plywood lid that snug fits in place. That is in turn covered by a waterproof layer of sheet metal (happened to be stainless steel leftover from a processing kitchen, but sheet aluminum or other sheet metal will do.

The box is attached by four wood screws through holes in the steel mounting frame.

Following the electrical wiring schematic, electrical components are laid out along one edge of the battery box and mounted securely. The whole electrical area is covered by a second small wooden box for protection when moving batteries in and out.

From left to right, looking toward the front of the tractor, we mounted a small fuse panel (shop-made, with a 400 amp fuse for operation and an 80 amp fuse for charging) a 48V DC computer fan for cooling (with bug screen), a small aluminum panel with the off-on switch (reated 48VDC), the Supnova battery monitor, the 5K potbox (accelerator), the 48V 500A DC contactor, the Curtis DC Motor Controller, with plenty of space to run heavy wires down from the motor controller to the motor. An opening was covered with screen to allow the small fan to move air across the DC motor controller.

An important step that was almost missed - the Curtis manual recommends that this motor controller be mounted on a metal surface. We're in a wooden box - already worried about too much heat in there! We found a hunk of aluminum plate to mount the motor controller on, and used four 1/4-20 screws to bolt the motor controller, and aluminum plate, to the side of the battery box. Airflow over this assembly will help to keep it cool.

Most components were mounted with 1/4-20 bolts, a few were mounted with tiny wood screws. Zip ties were used to organize everything before the small internal box was installed to protect the wiring from damage.

Motor installation follows the instructions from Neicamp Tool for their mechanical installation kit.

First, inventory the parts against Neicamp's parts list to make sure you received everything. Their kit comes in two shipping boxes.

I'll repeat the instructions here with some comments, but you should follow along the instructions in their kit as they come with important illustrations.

1. Using four cap screws provided, attach the motor to the Motor Plate. Align the terminals so they will be positioned at 10 and 2 o'clock with the plate's long edge horizontal, this will make wiring easier and shorten the path making it slightly more direct.
2. Attach the Stub Shaft and Larger Pulley Assembly to the Bell Housing Plate on the the same side as the four welded nuts using four of the 1/4-20x7/8" allen screws (no washers) provided. Tighten well.
3. Remove paper cover and Clamp Ring form the face of the large pulley and attach the Original Allis G Clutch disk (save this from dissassembling the tractor). You can throw out the rest of the clutch housing. Tighten the clamp ring bolts well to trap the clutch disk.
4. Pre-grease the pilot bearing through the zerk fitting to verify the grease has filled the passage up tot he bearing hole. later you will add two or three pumps more. Keep this area clean of dirt and grit while assembling.
5. Loosely attach the motor plate (with motor) to the bell housing adapter plate provided by Neicamp, using four 3/8-16X1-1/4" allen bolts with flat washers from the fastener bag.
6. Fit the shaft key and the Small Pulley with its bushing onto the motor shaft and position the pulley so that the belt will clear the surface when tightened. I had to take several tries to get this right. There are two set screws inside the Small Pulley that cause a cone-shaped bushing to be centered when tightened. Tighten the set screws together so that the Small Pulley runs true.
7. Put the belt over the pulleys and slide the motor on the motor plate to tension the belt, then tighten one of the bolts. The belt should deflect no more than 1/8" when finger pressure is applied at the center of the span. If the tension looks right then tighten the remaining bolts.
8. Assemble the Bell Housing Adapter and motor assembly onto the rear of the tractor at the back of the transmission bell housing. This requires slipping the OEM clutch disk over the tractor's clutch shaft, it will be a two-person operation. You may have to rock the tractor back and forth in gear, to get things to line up. Tighten bolts well.
9. Place the Motor Cover over the motor, after you have finished the wiring and double checked the proper motor rotation. Carefully insulate the motor terminals, in case the metal motor cover gets banged up somehow, and shorts out the motor.

We used a toggle switch to turn everything on, with a red panel indicator. We could have used a key switch, either one would work. We also could have an interlock switch under the seat, if the operator is not sitting on the seat, the tractor will stop, but we skipped this at the last second. Partly this is to prevent the tractor from being on when unattended, and running down the battery, as much as for safety. This toggle switch is rated for 48V DC, not a very common item but readily available on ebay or Amazon.

All control wiring is #16 stranded "Primary wire" or automotive type wire. Where this wire connects to a terminal we have soldered or crimped a terminal ring on the end.

Main wiring within the battery box is #2 Battery cable. This type of cable is rated for the high temperatures you might encounter in the field. Do not use house wiring, it is too stiff and not rated for this use.

The charger connection is #4 battery cable. This is way heavier than needed, but this cable will get a lot of abuse so we made it extra stout.

All high current removable connections are made with Anderson SB-175 connectors. Batteries are removable for winter storage. Grey Andersons are for the battery connections, red Andersons are for the charging connection. Different colors won't mate together by design.

High current terminals are crimped. Soldering such a thick wire is not easy, and ends up burning up the insulation while making the wire too stiff (believe me we tried this.) We bought a hydraulic wire crimper from Harbor Freight for about $69, something I should have bought years ago anyway.

From the Curtis installation manual:

"Connections to the controller busbars should be made with lugs suitable for the cable used, fastened by M8 bolts and nuts. When tightening the bolts, two opposing wrenches should be used. Failure to use the double-wrench technique could cause undue strain to be placed on the internal connections, and could also result in cracked seals around the busbars."

This double-wrench technique should be used anytime you are tightening connections where it is possible. We used it on the Curtis motor controller as well as on the motor terminals.

All heavy wiring (motor, batteries, etc) used heavy crimp terminals. Each crimp terminal had a length of heat shrink covering as much of the terminal as possible, connections at the battery were also coated with "Liquid Electrical Tape" to waterproof them. Battery terminals, already insulated with color coded caps, were also insulated with the corresponding color of liquid electrical tape for extra safety. More heat shrink tubing reinforces the wire where it crosses the edge of the battery box or the motor housing. Outside the battery box, heavy wiring is further reinforced with automotive wire loom. We really don't want any wires to short out on a metal edge.

The motor controller MUST be mounted on a metal surface. We found a heavy slab of aluminum plate that we used under the motor controller. DO NOT bolt the motor controller right against wood, it will get too hot. We further cooled the electronics by adding a 48V computer fan, and an equal-sized screened opening, to move air across the motor controller. The batteries can also get a little warm, not as severely as the motor controller, but some airflow in the battery box is helpful to them. Our battery box is nearly airtight (and is raintight) except for these fan openings - any heat would build up rapidly.

Batteries are strapped into the box using heavy nylon straps - hit a bump and these batteries will go flying if they are not strapped in.

A piece of sheet stainless steel, left over from the farm kitchen build, was used to give the battery box a raintight cover.

A 5K "Potbox" is used for the throttle. This is housed inside the battery box, however it is robust enough that it could be mounted on the tractor. We used a bicycle brake cable to communicate between the OEM throttle on the tractor (a simple lever with stops) and the 5K potbox throttle. A small tab was welded onto the transmission housing to accommodate the bike brake cable. The existing throttle (with a new 1/4-20 bolt) was sufficient to clamp the brake cable and actuate it. There is a short video in supporting files showing this in action.

See the attached wiring diagram for details.

The charger is built up from a series of Mean Well power supplies. Do not use a knock-off, many imitations are out there and usually aren't reliable. Mean Well units are famously robust, they are adjustable, come with internal cooling fans, however they are not waterproof and need to be inside a case for electrical safety. We mounted them on a plywood box, built a screen cover to keep out mud-dobber wasps. This charger case is mounted to the wall inside a watertight building where the tractor will be charged.

One of our authors has another Instructible on how to use several Mean Well power supplies to charge Ebike batteries.

The power to the tractor is brought out using some heavy flexible cables we happened to have on the farm. A red 175 A Anderson connector is used to charge the tractor, similar to the connector used by many forklifts.

Mean Well Power supplies are adjustable, and may be "stacked" on the DC side to achieve higher voltages and power. We used three 12 volt and one 15 volt DC power supplies, and adjusted the total to achieve 56.1 volts, in the recommended range of charging voltage. The 12 volt supplies can be adjusted to 13.2volts, the 15 nominal can be adjusted up to 16.5 volts, add them up in series and the result allows adjustment to the required 56.1 volts. Current for charging will be limited to 30 amps by the 15 volt supply, the 12 volt supplies are capable of more however in series, the weakest link controls the current. These power supplies regulate both current and voltage - they will provide no more than the rated current, and if the load attempts to draw more than this, the voltage on the power supply will drop. This is exactly the characteristic needed to safely charge Lithium batteries.

Critical step: on older Mean Well power supplies like we have used, there is a switch on the side of the unit to choose between 120V and 230V. Make sure to switch this to the proper voltage before assembling the power supply. Failure to do this will cause the power supply to not function.

An 80 amp fuse is installed in the DC line in case there is a problem with the charging circuit. There is a 240 volt, 30 amp double pole switch on the input side to turn the charger on and off. It is designed to plug into our 50 amp welding outlet in our barn. The plug is called a NEMA 6-50P style, and is commonly used for welders and other heavy 240V equipment. We used 240 volt instead of 120 volt, as the load would have been too great for a standard 120 volt 20 amp circuit. Each of the power supplies draws 6 amps at 240 volts, together they total 24 amps at 240 volts.

Datasheet for the Mean Well LRS-450 series is attached - other 450 watt power supplies by Mean Well can be added, in fact we mixed and matched two LRS-450's and two SE-450's.

See attached wiring diagram for more details.

We have reached a very important and dangerous step. The first time you turn on the motors and drives make sure the tractors wheels are up on blocks or jack stands, and that the wheels do not touch the ground. The tractor may lurch forward, or run in the opposite direction from what you expect when you first turn it on. If you are not ready for this, the tractor could easily run away and wreak havok on your shop or your twinkle-toes. Jack up the tractor so the back wheels are off the ground before making the final connections to the motor!

In our case, the tractor ran backwards! Much puzzling over the wiring diagrams allowed up to swap the motor wires to achieve forward operation in forward gear.

The motor transmission is used to achieve reverse. We could have added an electrical reversing circuit with another contactor, the Curtis manual goes over this in detail, but it is not necessary in a tractor with a good transmission.

Test the functions of the tractor - does the transmission work properly in forward and reverse? All gears? Ours originally had a klunking sound in first gear, other gears were fine. We are swapping the transmission out with another donor Allis G to fix it.

Once we had it in working order, we took it down off the jacks and Antonio had a tour of the farm!

A note about brakes. We had problems with the brakes on the tractor, and initially we have just left them off. The throttle is the brake. This has worked OK so far on our flat farm, where we do not operate tractors on any roads. I do recommend that you get your tractor's brakes running and we may well do so ourselves.

The Allis G electric conversion should be a long-lived, efficient and welcome addition to our stable of farm machinery.

If we did this project again, here are some things we might try:

1. Metal battery box. This would be a more formidable thing to build, but would be more durable and waterproof. Metal would dissipate heat better. Might not need an electric fan to keep it all cool.
2. Move the batteries forward. We have trouble using the rear-mounted implements with this battery box design. If the batteries were mounted in two boxes either side of the front end of the tractor, out of the way of the implements, then they would provide weight in the front (useful on any tractor) as well as allow the use of the rear implements better. We would still mount a control box behind the seat, just not so large. This would require longer battery cables and expense, but might have some advantages.
3.