Help: Want a simple motor for my trike

[BarryTrike]

Hi,

I built the no-weld plywood recumbent trike, described here:

http://www.greatuserdocs.com/trike0.htm

Now, I would like to add an electric motor assist to help me get up the occasional hill (like right by my house). The hill is not too steep, but is too much for my weak knees and heavy trike. :? The motor would only run for about 5-10 minutes, and maybe 2-4 km/hour going up a few hills, on a typical ride. I am happy to pedal the trike on flats and gentle hills.

Since the trike was built from salvaged parts, I would like to keep the cost low. Preferably salvaged parts for this modification.

The trike has the rear left wheel equipped with the rear bicycle cassette (only the right rear wheel is pedaled through an 18 speed bicycle chain setup), so I would like to connect the motor via bicycle chain to this left wheel; the motor could be attached to the base of the trike. I would like to use simple lead-acid batteries.

I thought of using an automobile starter motor, but its connection to the chain might be a problem. I've seen a few web articles on using/modifying these motors. Here's one link: http://homepages.which.net/~paul.hills/Motors/Starters/StartersBody.html

My question: does anyone know of a source of a salvage/used motors that might work here? Is the automobile starter motor a good idea to pursue?

Thanks,
Barry

 

[jmygann]

I would go with a front hub motor

 

[spinningmagnets]

I like your steering linkage. I think Amberwolf did something similar...as for a budget motor and where on the bike to incorporate it, I'll have to think about that one for a bit...

 

[dogman dan]

cordless drill, or weed whacker? cordless lawnmower? Something like that.

 

[John in CR]

For those kind of low speeds a wheelchair motor with its gearbox is a good solution with the right output rpm for you needs. Then you can use a cheap brushed controller. Check ebay for bargains on the motors.

 

[Drunkskunk]

A Starter motor is way to powerfull, and has a very short duty cycle. they're also extreamly heavy and would need a huge battery as there starting current is huge.

Cordless lawnmowers are often cheap on craigs list. they have a light but powerfull motor with a 100% duty cycle, and often will have the batteries needed to.

 

[GMDealer]

Hi,

I built the no-weld plywood recumbent trike, described here:

http://www.greatuserdocs.com/trike0.htm

Now, I would like to add an electric motor assist to help me get up the occasional hill (like right by my house). The hill is not too steep, but is too much for my weak knees and heavy trike. :? The motor would only run for about 5-10 minutes, and maybe 2-4 km/hour going up a few hills, on a typical ride. I am happy to pedal the trike on flats and gentle hills.

Since the trike was built from salvaged parts, I would like to keep the cost low. Preferably salvaged parts for this modification.

The trike has the rear left wheel equipped with the rear bicycle cassette (only the right rear wheel is pedaled through an 18 speed bicycle chain setup), so I would like to connect the motor via bicycle chain to this left wheel; the motor could be attached to the base of the trike. I would like to use simple lead-acid batteries.

I thought of using an automobile starter motor, but its connection to the chain might be a problem. I've seen a few web articles on using/modifying these motors. Here's one link: http://homepages.which.net/~paul.hills/Motors/Starters/StartersBody.html

My question: does anyone know of a source of a salvage/used motors that might work here? Is the automobile starter motor a good idea to pursue?

Thanks,
Barry

Hi Barry.

Easy answer. Front Hub drive motor with some oomph behind it. I ride a trike with a front hub motor. You can see the WE at http://www.i70west.com and see how easy an add it is. I even carry extra battery packs for some unbelievable range that you just can't get with a 2 wheeler.

 

[BarryTrike]

A Starter motor is way to powerfull, and has a very short duty cycle. they're also extreamly heavy and would need a huge battery as there starting current is huge.

Cordless lawnmowers are often cheap on craigs list. they have a light but powerfull motor with a 100% duty cycle, and often will have the batteries needed to.

Thank you....I'm now looking into cordless lawnmowers. Sounds like a great fit, especially since I can set up my desired gearing.

Barry

 

[amberwolf]

My question: does anyone know of a source of a salvage/used motors that might work here? Is the automobile starter motor a good idea to pursue?

Given the speed they run at is easy to gear up or down from with little change in ratio, John in CR's wheelchair motor suggestion is the simplest to implement. It is a brushed motor, and so any controller for it is very cheap and simple (even a switch would work but I highly recommend an actual controller and throttle).

I last used a 4-pole 650W 24V powerchair motor with gearbox output of ~120-130RPM at that voltage to drive CrazyBike2, before changing to the hubmotor it has at the moment. I ran the motor at 36V and then at 48V, gearing the output of the motor into the bike drivetrain for ~90-100RPM at full throttle (so it would match my pedal input and the speeds the bike gearing was "meant" for).

If you don't need speed then you can gear 1:1 and you will get the same kind of pulling power that this motor could produce on a powerchair/wheelchair, depending on the wheel size it was originally intended to drive. Some of them are meant to drive 20" or 24" wheels, most drive 10" wheels.

If you get one that still has the wheel on it, then you also have the hub which comes off the wheel with (usually) 4 bolts, and you can simply bolt a sprocket directly to that, and use that to drive the bike's left wheel (via the wheel's freewheel or cassette if you like).

If you get a whole powerchair, then you also have the 24V controller and throttle assembly.

I still have a 300W motor with gearbox somewhere around here that I haven't used in a while, which I could part with for shipping and packing costs (not sure I have packing material sufficient for it at the moment, given how they toss boxes around, they are heavy motors). It's well-used but it was well-used before I got it, too, and it worked the same before and after. They're tough little buggers. About 15lbs, though, IIRC. I don't have a controller just now, but I betcha McDesign still has some brushed controllers and throttles in that haul of his.

If you want to find one locally, check your local thrift stores and goodwills, it is possible they have a dead powerchair that they can't sell for a good price that you can get cheap. Craigslist is a good place to check, too, or you can put a Wanted up on Freecycle.org lists for your area.


The nice thing about these gearboxes is that they have a flat top with four to six bolt holes intended to bolt to a flat plate or clamp around a wheelchair frame, so you could very easily bolt it to your wooden platform next to the wheel (although I recommend a steel reinforcement plate and angle iron to keep it from flexing and derailing the chain. )

 

[lifepo4ever]

man just wait and keep some money a little bit and buy at least a cheap kit with hub motor brushed or brushlesss like this ebike.ca or powermotion, or ebikekit.com

you better use something will last so you can enjoy long trip and hassle free believe me ! its worth the money my first build with a car starter and only 600km of life with

 

[John in CR]

The OP said he wanted simple with slow speed up hills and pedal only the rest of the time using salvaged parts. That means DD hubmotors are out unless it's run out of the wheel and geared down, because speeds that slow up a hill with weight will kill any hub motor in a hurry. Maybe a geared hub can do it, but it's going to require lacing in a very small wheel, and the shock loads on plastic gears won't cut it with the high torque demand of a heavy trike. A wheelchair motor, though heavy, will run virtually silent and is built and geared almost perfectly to fit his needs. Plus they're easy to come by, and speaking of salvage, the 2nd salvaging generously offered by Amberwolf for only shipping cost fits the bill perfectly. I love hubmotors, but where are you going to find one for salvage?

The next closest thing I can think of is a multi-speed transmission heavy duty cordless drill such as the Dewalt hammer drills. The benefits would be light weight, and a multi-speed transmission may prove useful once he's spoiled by having electric assist. The lowest gearing on those is in the hundreds of rpm, so an easy geardown to the trike wheel is straightforward. Also it could be done with no controller at all using the tool's trigger as a throttle. The downsides would be noise, and continuous use would be in question, but helping up the occasional hill should be fine.

Salvaging a lawnmower motor could work, but I don't think simple can be included in the description, since it's going to require at least a 2 stage gear reduction.

John
John

 

[lifepo4ever]

The OP said he wanted simple with slow speed up hills and pedal only the rest of the time using salvaged parts. That means DD hubmotors are out unless it's run out of the wheel and geared down, because speeds that slow up a hill with weight will kill any hub motor in a hurry. Maybe a geared hub can do it, but it's going to require lacing in a very small wheel, and the shock loads on plastic gears won't cut it with the high torque demand of a heavy trike. A wheelchair motor, though heavy, will run virtually silent and is built and geared almost perfectly to fit his needs. Plus they're easy to come by, and speaking of salvage, the 2nd salvaging generously offered by Amberwolf for only shipping cost fits the bill perfectly. I love hubmotors, but where are you going to find one for salvage?

The next closest thing I can think of is a multi-speed transmission heavy duty cordless drill such as the Dewalt hammer drills. The benefits would be light weight, and a multi-speed transmission may prove useful once he's spoiled by having electric assist. The lowest gearing on those is in the hundreds of rpm, so an easy geardown to the trike wheel is straightforward. Also it could be done with no controller at all using the tool's trigger as a throttle. The downsides would be noise, and continuous use would be in question, but helping up the occasional hill should be fine.

Salvaging a lawnmower motor could work, but I don't think simple can be included in the description, since it's going to require at least a 2 stage gear reduction.

John
John

you right but when you have hub motor its so easy to gain speed he will like the feeling not like my 100volt lipo pack but a kind of speed he will love to travel
a wheel chair motor its more hassle to fit everything

 

[amberwolf]

I love hubmotors, but where are you going to find one for salvage?

It does happen, although you might have to repair it. I have four used ones now (technically all five of them are), two of which (both 48V Fusins from Dogman's meltoff) need actual repair before they can be used at all (one is in a wheel and the other is a bare motor), and a third which still needs to be laced into a wheel or be used stokemonkey style, and is itself actually two different brand motors (9C and GM) salvaged and combined to make one working one by Icecube57.

While hubmotors can simplify things, as you point out they don't do all that well at higher loads and slower speeds, for the same reasons any motor designed for higher speeds doesn't do as well if you load it the same way but run it down at it's high-current regions.

Salvaging a lawnmower motor could work, but I don't think simple can be included in the description, since it's going to require at least a 2 stage gear reduction.

This one I've pondered on my own, and it requires quite a lot of reduction. Most of these motors are running in the same speed range as fast RC motors AFAICR. Without the reduction they'll burn out quickly under even light (for ebikes) torque loads.

The same problem applies to treadmill motors (whcih can range from medium-duty to 100%-duty), and to garbage disposal motors (which are only light-duty), although these two are nearly always 100VDC+ motors, complicating things further.

 

[lifepo4ever]

with my 18 fets controller the power is so smooth and i can run the motor a 10mph with no heat in a hill my barbecue sensor stay at 50 degree i have to driil hole in the motor also i don't think i will go at 5mph anyway so please don't waste time with old motor already burn but if you like to fix the bike everyday like amberwolf does go for it !!

 

[amberwolf]

with my 18 fets controller the power is so smooth and i can run the motor a 10mph with no heat in a hill my barbecue sensor stay at 50 degree i have to driil hole in the motor

So you have to drill holes in the motor casing to keep it that cool? Exposing it's innards to the elements? Then that means in a maintenance-free non-drilled application, it would not remain that cool (although the temperature it *would* reach is unknown, as it depends on the weight of the bike+rider plus the length and slope of the hill).

also i don't think i will go at 5mph anyway so please don't waste time with old motor already burn

Whether *you* will go at 5mph is irrelevant, since this thread is about someone else's needs. As to whether an old motor is already burned or not, that can be irrelevant, too, because he may not use a burned one, just a used one. Just because a motor is used doesn't make it burned.

but if you like to fix the bike everyday like amberwolf does go for it !!

I don't have to fix mine everyday; I alter stuff all the time because it's all an ongoing experiment, and often fun. Bearing in mind that I don't always know what I'm doing or have the necessary fabrication skills and/or tools to do what i really should be doing, I do often enough have problems with some of those experiments (that's the nature of an experiment--to find out if it's a good or bad way of doing it).

With the powerchair chaindrive on CrazyBike2, it could be perfectly reliable if I eliminate the frame flex, which is what causes the derailing of the chain that destroys components (because it is so powerful a system). I'm just not all that competent a welder or designer yet, so the frame flexes too much, allowing alignment issues to form between the motor's drive sprocket and the drivetrain's receiver sprocket during high-torque startups and accelerations, and allowing the chain to then ride up on the edge of the sprocket. The same thing would happen if I was pedalling it that hard, too, unfortunately (though I can't actually push that hard due to my knees).


All that said, sure, a hubmotor and controller are one of the simplest options to use, but they are not the most efficient at hillclimbing, unless one gets a motor wound for slow speeds and/or puts it in a very small wheel, so that it can spin at the faster speeds it needs to reach to get BEMF down to where current flow is smaller. Problem is, when you do that, you are now restricted to those lower speeds completely, when using the motor to help, as it won't go faster (unless you put more voltage across it, which will make it hotter too, as it puts more power thru it). Plus you'd want one that freewheels when not using the motor assist, so that it has minimal drag when just pedalling.

Using something thru the gears on a bike allows one to simply use it as a pedal-assist, as this poster needs, on hills or on flats or wherever, at whatever speed is optimal for the motor for that grade and bike load.

It's still the original poster's choice what to do, of course; I just think that whatever motor is used would be better operating thru the bike's gears and chain.

 

[BarryTrike]

The next closest thing I can think of is a multi-speed transmission heavy duty cordless drill such as the Dewalt hammer drills. The benefits would be light weight, and a multi-speed transmission may prove useful once he's spoiled by having electric assist. The lowest gearing on those is in the hundreds of rpm, so an easy geardown to the trike wheel is straightforward. Also it could be done with no controller at all using the tool's trigger as a throttle. The downsides would be noise, and continuous use would be in question, but helping up the occasional hill should be fine.

Salvaging a lawnmower motor could work, but I don't think simple can be included in the description, since it's going to require at least a 2 stage gear reduction.

John
John

You folks are amazing!!!

I was settling in on the cordless lawnmower idea, and then you mentioned a heavy duty cordless drill.

What a superb solution!
I should be able to get one cheap, whose batteries ran down. After all I gave away a nice cordless drill whose batteries had died.

Just a question or three:

• How powerful does the drill have to be?
  How do I determine the power (can I just use the watts - hp conversion)? Hard question: what power -- depends on weight and the profile of the hill.
  
  Is a hammer drill the only type I could use?

I'm about to start looking on the used stuff website (mostly Kijiji) for the drill.

Regarding the cordless lawnmower, I hadn't yet thought about gearing (grief), thanks for those comments.

Amberwolf, thank you very much for the offer of the motor, but now I'm on the cordless drill path.

I had looked at driven (hubmotor)wheels (front) from goldenmotor. But I am mostly interested in the hill assist. Pedaling is OK, as long as my legs hold out.

Barry

 

[spinningmagnets]

It doesn't have to be a hammer-drill, its just that the hammer-drills are usually larger, and you want the largest cordless drill you can find. It 'might be' possible to find a large 36V DeWalt or Milwaukee (etc). Even the 28V models are pretty beefy.

The batteries for these are so expensive that when they wear out, its just a few dollars more to buy a new combo pack rather than just new batteries. Perhaps look at a local pawn shop? Also look for a 24V or bigger cordless circular saw. Ebay is another option.

It will likely be a brushed motor, That means the controllers will be cheap (from TNC?). The downside is that brushes don't do well under very heavy amp-draws, like when you have a load of cargo and are going up a steep hill slowly at full throttle.

I have seen a 3-speed hub (such as a Nexus) used as a transmission. I have also seen the common external gear cluster of a bicycle (just like on your right rear wheel). Either way will lower amp-draw to lower motor heat (plus brush current) and help the brushed motor survive. new brushes are cheap and easy to install, (but annoying).