I'm exploring the idea of powering a mountain bike with my cordless electric chainsaw. Many bikes have used chainsaws in the past. Noisy, stinky, gas guzzlers. My saw delivers amazing power for a cordless.
I like the idea of using what I already have. I have an Ego cordless electric chainsaw, hedge cutter, blower (on order) and I'm getting their lawnmower. All of this equipment runs on 56 volt lithium ion batteries. The chainsaw delivers about five times as much power as my legs do. I have to make some calls to verify that. A guy in decent shape can sustain about 200 watts.
The chainsaw/bike thing has been done to death. YouTube has many examples. It's all been done. Power from the sprocket is run through a chain gear reduction to get the right speed.
My plan is to present my tenant, Randy with the saw and bike, after we view all of those videos. He welds and he keeps 3 vehicles, 2 ATVs and an old excavator going. The mechanics won't be a problem. I don't want the saw to become a permanent part of the bike. It needs to pop on and off easily. That's the technical challenge.
Range --- This is the big deal to most people. Only a few trial runs will determine that. My hedge cutter is good for about 45 minutes of continuous use. The saw draws more power. It cuts so fast, that all jobs are done too quickly for me to know the answer. I expect to use the power when climbing hills and when accelerating. This should prevent over heating. The saw automatically shuts down if it gets too warm or if it is overloaded. In overload, it takes a one second break and it's ready to go again. Gearing will have to be tinkered with.
The saw, hedge cutter and blower each have their own 2 amp hour battery and charger. The lawnmower has a 4 amp hour battery. All are interchangeable. The hedge cutter is a little heavy when fitted with the lawnmower battery. For long trips, all batteries could be brought along. I have to find out what they weigh. I think it would be around 30 lb. with the saw and all batteries aboard. Mine charge in 33 minutes. I often charge multiple tools at coffee shops. I walk in with a duffle bag and my own power bar with 5 plugs. All batteries together, store about half of a kilowatt hour of power. This costs 4 cents in BC.
Hey dale one upside for biking on your trails would be slightly less Need for maintenance. I know that mountain bike trails stay pretty beaten down in the middle from all the riding, all the needs upkeep is trimming the overhanging stuff along the edges during the growing season. If you rode your trails during early spring it would really keep the growth to a more easily managed level. Goodluck.
Oh and check out thIs link with electric bikes with solar panels attached, very cool! The first one on the page is a surly big dummy frame as the base, with flexible solar panels arching over the top as a roof over the cargo load.
Dale Hodgins wrote: For long trips, all batteries could be brought along. I have to find out what they weigh. I think it would be around 30 lb. with the saw and all batteries aboard. Mine charge in 33 minutes. I often charge multiple tools at coffee shops. I walk in with a duffle bag and my own power bar with 5 plugs. All batteries together, store about half of a kilowatt hour of power. This costs 4 cents in BC.
According to Eco's website, the batteries weigh: 2.0ah = 1.3k, and the 4.0ah = 2.3k
They also make the following claims for their chargers:
* Standard charger: 40 minutes (2.0 ah battery) and 80 minutes (4.0 ah battery)
* Quick charger: 25 minutes, and 30 minutes.
Thanks John. That means I'd be packing about 8 kg or 20 lb with all batteries and chargers. I have the regular chargers and mine take 33 minutes to charge from completely dead. 30 lb seems about right, plus a chain, mountings etc. It needs to go on a well built bike.
I would probably be towing a trailer. For me, a bike like this would be used on the farm and in the city. Most of my jobs are within 5 km of downtown. All vegetable deliveries and 3 places where I gather coffee waste and seaweed, are within 1 km of the garden. I already get much more exercise than most people. I don't plan to increase my work load by pedaling very much.
This is what it looks like without the chain. Many small Oregon bars fit. A scrap one, would make a good spot to mount anything needed for the bike. The shaft from the brushless motor sticks about 3/4" out of the casing. I won't do anything that involves pulling the saw apart. A pulley or sprocket could be slipped over the chain sprocket and secured with Allen screws.
I gave it a short run without the bar and chain. It's super quiet. Most of the noise that the saw makes is from the chain's many joints. Bike chains or belts aren't as noisy. Oil came out when I ran it. I don't think it has a pump. It's probably gravity fed. If this is the case, I'll let the oil run out while cutting wood, before powering other things. If there is a pump, I'll check to see if it can safely be run dry.
Single speed --- The trigger is not variable. It is full power all of the time. This means that the bike would have to be in motion before the motor is activated. The chain speed varies according to the load but if the chain meets too much resistance, the overload protection cuts the power off. The bike would need to be driven in a surge and glide mode. That's how I drive a car, so not a problem. Hills would have to be climbed in a sufficiently low gear, so that the motor doesn't shut down.
There is room for the larger lawnmower battery to give double the run time.
I could see powering a pole saw, sump pump, go-cart, giant wheelbarrow etc. If a drill chuck were affixed to the shaft, any number of items could be powered given the right attachment and gearing.
Engineers at the company answered a few questions for me.
1. The unit's output is 840 watts. 1 hp=745 watts --- That's about double the output of an Olympic cyclist. It's about 5 times the power that I put into my mid exertion jaunts. So, as I suspected, there's plenty of power for hill climbing and accelerating.
2. The battery holds about 350-400 watt hours of power. That's about the amount of power produced by our Olympian in one hour. It takes the saw about 25 minutes to consume that power. I could see getting an hour out of it, when lights and gliding are accounted for.
3. Overheating should not be an issue. A fan cools the motor when in use.
Once I have the lawnmower and blower, I will have 5 times the battery power of a single tool, and far more power than I'd likely use to power a bike in a day.
I've checked out the output of several 1 hp sump pumps. When lifting water five feet high, they are able to move about 160 gallons per minute. I'm likely to need to lift water 15 feet. The saw motor will be able to lift about 50 gpm. If it does this for 20 minutes, a full charge should pump 1000 gallons. That's 4 tons of water. Given a compatible pump, this would be a convenient and very mobile power source. No need to set timers. Turn it on and let it go. When the battery dies, it's done. No need to piss around with generators.
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