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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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Electric Tractor Testing

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As I mentioned in the previous post, the next stage of the project was to quantify the size of the battery pack I would need for the electric tractor to cover what I'll be using the tractor for on our 4ha lifestyle block.

Here's a video of the first significant test run using a 1.5m rotary slasher to mow some grass:

Shots of the gauges didn't show very well in the original video, so I did a second identical test run and added the gauge videos as overlays. Hope this helps to show the electric running performance. Apologies for my commentary where I keep over-estimating the Amps being used though - I was remembering usage from previous 36V test runs, but now that it's using 72V the Amps are lower ðŸ˜ƒ.

Second test run was pulling a heavy groundhog implement that levels, aerates and seeds paddocks:


I also did a number of other test runs, including using the tractor to cart a truckload of crusher dust into paddock gateways using a back-bucket, and recorded the resulting power usage. I then used the results to estimate the power usage for my typical predicted use of the eTractor:

Table of electric tractor test run power usage data

From the above data I reckon I will need a battery pack that meets the following requirements:

  • Voltage:                   72V  (6x 12V or 23x 3.2V)
  • Peak Amp:              150A  
  • Usable Capacity:    120Ah  (based on C2 = 60A/h avg)
  • Max Size:               520W x 750L x 500H   

 On exploring options from NZ suppliers I shortlisted to the following:


In the end I went with Supplier B even though the most expensive. Having local support in NZ being the main decider, plus they could supply the fastest too.

Battery pack and charger are now on order, so watch out for the next post when I get the battery pack and put it through its paces...

Location: Vaile Road, Waikato 3286, New Zealand

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