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Electric Tractor Project Overview (Plan A)

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    1967 David Brown 880 Selectamatic Can we make it an eTractor? Yes, we can (well, we will see 😃)  After completing other electric scooter projects (see Electric Joker ) I wanted to do something more challenging. Thought about converting a car, but there's way too many requirements to complete a road legal conversion. So, why not a tractor for use on our lifestyle block? Why did I choose a David Brown tractor for my Electric Tractor project? Mainly because I wanted a tractor that didn't rely on the petrol/diesel engine (ICE - internal combustion engine) to connect the front frame and wheels to the rest of the tractor. Looked around for a few potential options - Fergies and Fords were out, but David Browns seemed like a good option. Looking at the David Brown 880 my initial plan (Plan A) was:   The David Brown 880 picture below shows you the tractor and how the major engine and transmission components are laid out. And, the following gives an exploded view of thos
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Rear End Refurb Done and Electrics Planned

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David Brown 880 rear end refurbishment completed

Drained and replaced transmission & hydraulics oil and filters. Rebuilt the steering column and rack. Repaired rust in guards. A lick of paint and the rear of the tractor is now looking sweet!

David Brown 880 electric tractor rear refurbished

Motors, controllers, test batteries and a few other parts recently arrived. So, I could then mock up the electrics layout:

Mock up of electric motor layout for etractor project

My father-in-law is a design engineer, so he's now designed mounting brackets for the motors and shaft bearings, and we've confirmed timing belt pulley and belt sizes. So, with those all on order it's more waiting now for a while 😀. But, it's all starting to come together...

Mockup layout of motors and batteries for electric tractor conversion

However, I bet you are interested in what motors and controllers I've gone with?

I'm hoping I've done my sums right on the motors, at least for my needs anyway. We only have a small (12 acre), flat lifestyle block of land, so I don't need the tractor to do anything too meaty. Mainly towing a small car trailer around with hay on it and occasionally topping (small 1.5m slasher mower) some paddocks (takes about 20mins to top a paddock with my current Fergie 135 tractor).

I've also bought these cheaper motors and controllers to start with, in case I have got it wrong. If I have to 'upgrade' to bigger - better motor(s) later, I'm ok with that. I've also gone with two different types of motors and controllers too, just to make the project even more interesting 😂. The motors and controllers details are as follows:


QS-Motor QS-180 & Far Driver ND72850B Controller

For the transmission: a QS-Motor QS-180 motor (with encoder, not hall sensors) with Far Driver ND72850B (encoder version) controller. Hope we get the 8kW rated (@4200rpm) & 15kW peak (@6000rpm) and 18.2Nm of rated torque & 65Nm of peak torque (@1895rpm) => Using the planned 2.6:1 reduction (T10 timing pulley with 18 teeth on the motor and a pulley with 48teeth on the transmission shaft) the peak torque 1895 RPM equates to 728 shaft rpm, which was pretty much the idle speed of the diesel engine.



Golden Motor 10kW motor & VEC500 controller

For the PTO: a Golden Motor - HPM-10kW motor with Golden Motor VEC500 controller. Should give 10kW rated (@3700rpm) & 20kW peak (5000rpm) and 26Nm rated & 85Nm peak torque (again with 2.6:1 reduction - 24 teeth pulley for motor and 60 teeth pulley for PTO shaft - it will increase the torque and power to the PTO shaft). The VEC500 has cruise control, which I hope will be good for holding PTO speed too.

Both motors running at peak power/torque is around 400A using 48V, so hopefully it's all enough. For comparison the David Brown 880 ICE had peak 47Hp (35kW), when new, and 120 lb ft (160Nm) of torque. So, with the 2.6:1 reduction and split load across the motors, I'm hoping we're within the realms of usability.

Next post should see a few more things coming together...




Location: Newstead 3286, New Zealand

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