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BCS rototiller (2-wheel tractor) conversion

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I've been working on a conversion for our BCS 2-wheel tractor and I'm not finished but it's going pretty well and I wanted to share, partly because it's related to some work others have documented and shared here and partly because it's something that small-scale vegetable farmers like me have been dreaming of doing for some time but it wasn't really feasible until good lithium cells were available at a reasonable price - the weight of lead made it impossible.

These machines are called 2-wheel tractors or walk-behind tractors or walking tractors because they can pull draft loads and also drive PTO-driven tools and because tools are numerous and they are interchangeable, even between brands to a certain extent.

Our tractor is an older (circa Y2K mfr) Italian machine called a BCS model 730GX11 meaning it was powered by a Honda GX340 ICE developing 11hp. It has a full oil-bath gear transmission with 3 non-synchromesh sliding gears and a reverser mechanism as well as a lockable diff. Power delivery is through a cone clutch which is bolted to keyed output shaft of Honda engine. Single clutch for traction and PTO thus they are engaged at the same time. PTO can be disengaged by lever and should be kicked out of engagement any time reverser flips to reverse travel direction with rear-mounted tool. I mention this because it's something I have to duplicate in the electric version where I'm not using the gear reverser mechanism if I can avoid it.

Anyway, instead of going on and on I'll try to make this succinct.

I found an appropriate motor (AMD DD0-4002 sepex 6.7") thanks to fate and I made an adapter plate to mount in place of Honda GX. removed clutch and used scrap clutch provided by sympathetic BCS retailer to make coupler shaft from DC motors 7/8" shaft to BCS splined metric input shaft, including dbl roller chain union in driveline to eat the poor alignment inherent in my marginal machining tools.

The motor mounts directly to the tractor frame bell housing and mounting plate also provides tabs to support a battery and controller cradle subframe which I slowly assembled out of various bit of scrap metal on hand. The goal was to keep it tight and tidy and I'm happy with the results. Airflow has to be managed so there are some partitions made from tractor inner tube that cause the motor to only draw in at the front and then expel air up under controller's aluminium mounting plate.

The controller is a second-hand Curtis 1243 that seems well-suited to the task at 300A 24V peak.

Batteries are 6S 24V modules from Chevy Volt battery packaged in waterproof ammo boxes, each with their own voltmeter, low voltage buzzer, ANL fuse and balance cable for periodic balancing. They're a very tight fit in the PA19 ammo boxes and it takes some time to assemble one but it's a pretty solid little 30 pound kWh when you're done so I'm happy with them.

Batteries are wired in parallel and system runs at 24V so batteries can be used singly or as a pair which can prove quite handy. We currently only have two tools for our BCS - a rototiller which we're trying to use less, and a rotary harrow that's less hard on soil structure. The rotary harrow is more than 30lbs heavier than the rototiller so the 2nd battery helps to rebalance the machine whereas for the rototiller a single battery balances it better. My goal is to have 4 or 5 of these "power brick" batteries on the farm, shared between a set of 24V tools including the rototiller, pallet jigger, earth auger and others. There should always be one or two charged and waiting if you need to do a big job and run down more than one or two batteries.

There are some videos of the early process and a first test run on YouTube if you search for my name "Reid Allaway". More complete photo album on my Facebook page because I haven't yet found a better place to document.

I hope these ideas help someone and I'd be really interested to know if others have or are planning to undertake such a project.

I'll post new pics when I finish the controls and top cowl/cover.

Thanks to everyone here at DIYelectriccar for inspiring and encouraging each other. I might not be tackling projects like this if I didn't know the community of enthusiasts was there to support me if I needed it.

~ reid Allaway
Ferme Coopérative Tourne-Sol
les Cèdres, QC


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· Registered
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Discussion Starter · #2 ·
Conversion was put on ice for most of the season due to time constraints. I grudgingly reinstalled the ICE and it ran as reliably and stinky as ever through a good busy spring and summer in both the unheated greenhouses and the field.

Luckily, a friend made progress on his similar project, got his finished and gave me to proverbial kick in the pants to finish mine so I started working on it again in the evenings a couple weeks ago.

It's now finally finished and working properly and I think I can put the Honda engine up for sale and throw away a couple jerry cans 'cause it's never going back to ICE while I'm here.

Here are a few new pics and a link to a long-winded video walkthrough that's aimed more at folks who don't know EVs because mostly it's other farmers who are excited about this project and ask me all manner of questions. So I shot a long, rambling video and now I can direct them there with their questions.

Anyway. I'd say the project is a big success. The machine is back in service, almost daily, on our commercial organic vegetable farm and it seems likely that I'll be able to make little improvements over time without having to redesign it significantly. For a prototype it's doing admirably well.

~ Reid


· Registered
994 Posts
The more I think about what you've done here, the more I like it! The water-proof, rugged, interchangeable battery system you've developed could be used on rotary push mowers, converted riding mowers, converted snow blowers, small forklifts(like you've done), quads and other equipment. This could be in series and parallel battery combinations on various equipment, in addition to the many possible BCS attachments.

One concern I've had with dedicated single use battery packs, say on a converted Troybilt or a BCS tiller, was that they would only be used for a short period of time seasonally during the year. This would be kind-of a waste of expensive battery capacity. Your system addresses that concern by conveniently using the batteries on other pieces of equipment. Great work!

Any concerns about cooling the volt cells? Could you draw up schematic of your wiring of the BCS? Have you thought about attaching the Anderson plugs directly to the ammo boxes that would automatically plug into Andersons built into the cradles?

· Registered
67 Posts
Discussion Starter · #4 ·
Thanks for the kind words electro wrks.

I really do think that these power brick units, or ammo can power units (ACPU) as a friend dubbed them, are going to be super handy with a multitude of uses.

I have a forklift steering motor with a cycloidal gear reducer and want to make a 1 or 2-man earth auger with it but I'm also keen to look at repowering a brush saw/weed whacker and also maybe a small chainsaw for limbing and pruning work. I'd like to rig up a backpack harness that will let me carry one of these 1kWh bricks around on my back and deliver portable power at 24VDC to whatever tool I can conjure up. 30 lbs in a waterproof armored case seems pretty good to me for 1kWh and I keep thinking of other things I could use it for.

This idea of portability, and the existing config of my pallet jigger with mounted Anderson connector was what led me to keep the SB175s on a flexible cable tether rather than pinning them to the case and making a mating cradle. All told I think that the positive lock-in cradle would be really cool but perhaps more trouble than it's worth and possibly less flexible (sic) a design overall.

Keep pitching ideas as they come. I hadn't thought of a rotary push mower yet - good one.

I will try to draw up the wiring diagram and post it but it's not very complicated.

thanks for the interest and encouragement.

~ reid

· Registered
67 Posts
Discussion Starter · #5 · (Edited)
Electric auger up and running a couple weeks ago. Worked like a charm and ably twisted in a couple hundred ground anchors that would have otherwise been a terrible pain, as in all years past.

The unit proved really heavy to manage until my wife found a shoulder harness that allows the auger to hang from your front and the battery pack to hang from your back. Downright ridiculous but surprisingly tolerable for an hour or so at a time. One side effect of this configuration is that whoever wears the getup quickly becomes the Augernator :cool: and starts talking a bit like Shwarzenegger but it's cured when the suit comes off :)

The task of driving in 200 ground anchors drained one 1kWh battery pack by only about 50%!

Videos on YouTube.

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