I call this snow machine the "Sk-E-Doo", and it is one of Canada's first fully-electric, zero-emission electric snowmobiles. I can honestly say that it is just the perfect way for a cottager to enjoy this sport without the environmental concerns associated with snowmobile emissions. It performs very much like a gas-powered sled, but quieter (though not as much as I had hoped due to the unavoidable track and gear noise) and it is a blast to drive! This amazing "cottage toy" is now added to the electric boat I purchased last Spring as well as the electric car I drive around my Tamarack Lake cottage area (near Gooderham, Ontario). Since there was nothing available on the market I decided to build it myself.

Technologically, this "proof-of-concept" machine utilizes Ni-Cad batteries I purchased surplus from Bombardier's engineering department (left surplus after the cancellation of the NV) and uses a PWM controller and series-wound DC motor. It also has a DC-DC converter to keep my auxiliary battery charged at all times. The chassis is a converted 1971 Gilson sled, which I chose for its robustness, track size and large front hood area to accommodate the batteries.

How did this project begin? Well, my other electric vehicles work great, so I began to wonder why the fun couldn't continue even in the coldest winter months. What if a snowmobile were converted to battery-electric power? Wouldn’t that be fun! As is normal with my EV projects, I opened up napkin and sketched the basics asking myself questions like: where do the batteries go? How many and of what type? AC or DC power? At some point, the questions stopped and the answers started to trickle in. I recognized that the challenge would be great and simply put, snowmobiles aren’t cars or boats and to make a practical electric sled wouldn’t be the same as a lead-acid conversion of an internal-combustion car. I would be working with much less space and if the battery distribution wasn’t properly considered, the nose would dive down into the snow and the track would spin wildly without forward motion. Furthermore, these machines are wellknown to be very inefficient, with most of the energy wasted in overcoming track resistance, a considerable hindrance.

I hit the ground running and by October, I had chosen an ideal chassis for conversion. I chose to convert, rather than purpose-build, to save time, money and as a logical starting point until I understood the dynamics of snowmobiles much better and felt comfortable designing from scratch. I decided to treat this project as a “proof-of-concept” rather than a completed thought and my final word on the subject.

A 1971 Gilson 440 2-stroke snowmobile was chosen (I know, a what??!!) which ironically had a running-but-smokey Kohler 2-cylinder motor which I was very quick to yank out. The chassis was perfect – it had a very wide 18” track which went from the front of the machine to the very back, giving the sled an excellent track footprint to carry the extra weight I would be adding. The frame and tunnel were made of steel, unfortunately a little heavier but worth it since I would be afraid of warping or buckling a lighter-built frame due to the high torque and heavy weight. It was designed to have a gas tank in the very rear of the machine, which would prove useful for weight distribution since batteries could be mounted in its place. To top it off, the front, although not pretty by anyone’s standards, was a great big box and if there’s anything a potential EV converter loves, it’s a great big box to package all those batteries!

I didn’t have an unlimited budget, so I looked around my shop to identify surplus stuff I already own which could prove useful. Given that this vehicle will be expected to always perform in colder weather, I decided to use some of the SAFT STM100 (100 amp-hour) Nickel-Cadmium batteries I had left over from the ElectriFly project. I also had a Curtis 1221 controller (72 – 120 volts DC input) so that also formed a starting point. At 6 volts apiece, I would require 12 Ni-Cads, each approximately 5”w X 10”l X 10”h (totalling 3 ½ cubic feet) and weighing 27 lbs. each… doable, but with much challenge ahead! I also had a 72-volt lead-acid charger (suitable for an “opportunity charger” in the bush) which would give comfort should I need a boost while I’m out on the trails, so I could see the plan coming together as a 72-volt traction system. A trip to D&D Motors in Syracuse in October yielded a great power plant, a DC series-wound motor at a very reasonable price rated at 27 hp continuous which was a perfect match to my controller. Add an Albright emergency disconnect, an old GE contactor, a PB6 potbox (governed down to 3,500 from 5,000), a few trips to Princess Auto and a DC-DC converter which my good friend Darius Vakili at ElectroCraft built and gave me years ago and voila! we have a complete plan.

Nothing was simple about the packaging of so many batteries. I had to place two in the very back of the machine, three between my knees, four in front of those and three more on top of the electric motor! Oh, and I also found a little spot to put a small lead-acid auxiliary battery (constantly recharged off of the main pack through the DC-DC converter) to power the main contactor and headlights only. The main thought in my mind was this – I wanted to keep as much weight over the track as possible and as little as possible on the front skis. In the final analysis, I succeeded in placing about 70% over the track! I don’t believe that this would have been possible on a newer design of sled without a major re-design.

Using the computer print-out from D&D Motors, I chose a gear ratio which maximizes efficiency (about 85% at about 4,000 rpm) at 40 kph (25 mph), my target “cruising speed” of the machine. This yielded an overall ratio of about 3.5:1 and accounting for the stock transfer case ratio, I chose sprockets for the electric motor and secondary shaft which produced those results. I modified the stock braking system, which works off of the secondary shaft, saving me time and effort to redesign and fabricate. I had some serious packaging difficulties and had to raise the hood by about 1” to accommodate the required height. The rest seemed to bolt together easily and after about 120 hours, I was finished the “Sk-E-Doo”, Canada’s first electric snowmobile (with apologies to Armand Bombardier). Does it work? You bet! It accelerates briskly, as all electrics do, and I cruise at the designed-speed of 40 kph (25 mph) easily. A little slower up the hills and a little faster down them. My range is about 30 kilometres (~19 miles), which is more than adequate for my family’s recreational enjoyment. It is quieter than a gas-powered sled, although there is still gear and track noise which I think can be minimized on a purpose-built machine. We have enjoyed many outings with the sled, no incidents to report, and we particularly enjoy the night trips we have taken around and on our lake.

Remember I said that the motor/controller system is rated for 72 – 120 volts? Well this leads to the next phase which I am currently working on. It involves a pull-behind range-extender “Sk-E-Boose” trailer which will also carry my daughter (and payload) so that my entire family can go on local excursions. I hope to have it finished before the 2004 snowmobiling season ends. The machine will operate with or without the Sk-E-Boose, I will simply connect or disconnect the trailer hitch and electrical connector when required. The controller will “see” 120 volts if the trailer is connected and 72 volts if it isn’t. A simple arrangement, it should add about 10 more miles of range to the set-up.

Although I built this primarily for guilt-free snowmobiling enjoyment at our cottage and as a "proof-of-concept" machine I will also build another one, designed specifically to be an electric rather than a conversion. It will have fully-optimized performance, improving in every aspect over my current machine, possibly utilizing lithium batteries. I hope to finish this "pre-production prototype" before this season ends.

McGill University is currently building Canada's second electric snowmobile and we are exchanging notes and observations as they progress.

3/2/2004 Story Update

The amazing electric Sk-E-Doo just got better!

Last weekend I finished the work required to complete the "Sk-E-Boose", a range-extending, kid-hauling, trailer attachment for my electric snowmobile. This pretty much completes the e-mobile project and it is a fully qualified success! The Sk-E-Boose carries 8 Saft Ni-Cad batteries (at 6 volts/100 amphours each, that equals 48 additional volts) which is connected in series with the snowmobile's 72 volts to give me a nominal potential of 120 volts. Although I have yet to have an opportunity to test increased range due to poor snow conditions at the cottage at this time, I estimate that it will add about 10 miles to my existing range of 20 to give me a real-life range of about 30+ miles carrying myself, my wife and my daughter. It takes off a lot faster now (although it wasn't slow before, I might add...) and it's top speed seems a little higher at about 40 mph, which I have governed down a bit. The Sk-E-Boose also gives us the opportunity to carry supplies and luggage from our car to the cottage as well. All the fun, but without the guilt...

Monte Gisborne lives in Whitby, Ontario. He is a member of the Electric Vehicle Society of Canada and this story first appeared in the January/February edition of the Ontario Electric Vehicle Newsletter. For more info please take a moment to visit the related links below.