# Motor Selection for a Reverse (Tadpole) Trike



## nheistand (Jun 2, 2009)

Since an ETek type motor will power a motorcycle 40mph, two of them would give a lot of torque. Why not put one on each drive wheel, then you do not need a heavy transaxle or differential. The typical electric motorcycle with an Etek setup uses a 12 tooth chain sprocket on the motor and a 72 tooth sprocket on the rear wheel. A cog belt might be an alternative. 

For turning I would use a microswitch to cut the throttle input to the inside wheel. With a little experimenting you could adjust it so the switch would kick in when it "feels right" to you for cornering.

I can envision two golf cart motors and controllers and some roller chain or cogbelt to take the place of a single setup for a car conversion. So far I am unable to convince myself that the dual golf cart setup would have as much power as my Impulse 9 motor and 96v system. It would be some cheaper, but probably not a lot. I think my Impulse 9 does 90hp peak with the Curtis 1231 controller. That would be a lot of golf cart motors. 

Grade School math says we can add together the torque for two motors. Now we just need the right amount of torque and the proper gearing to get the speed we want. Maybe we can get rebuilt golf cart motors and controllers at low cost and use 3 or more of them?


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## Atarijedi (Apr 1, 2009)

haha, yeah, a golf cart motor is like 5hp max. The one I sold not long ago from my old EZ-GO was 2hp.

There will be only 1 drive wheel, the rear one.

I don't want to have to mess with differentials or transmissions or anything if I dont have to. That is why I was originally thinking of using the 2 motors back to back (I think people call it Siamese), each one would have a sprocket or cog and be connected to the rear wheel on its side with a sprocket or cog. 

This seemed like the simplest way to do it since it is possible to direct drive with these kinds of motors. I want to keep it as simple as possible since there is a lot of other complex things I need to get into.

So again I would have a swing arm on each side (essentially an A-arm), and a sprocket on each side of the rear wheel, each sprocket connected to a motor via a chain, and the motors would be run in Series or Parallel, maybe even switching between.


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## Atarijedi (Apr 1, 2009)

Okie, so it seems that people converting Bicycles to use Electric as well as Man power use a special hub called a FlipFlop hub on their rear wheel, it is essentially a hub with a sprocket on each side, so I am wondering if something similar is/could be made for a motorcycle wheel.

I just realized that I wont have a rear brake, but I will have 2 front disc brakes, as well as the regenerative braking, hopefully this will be enough. If the vehicle does get classed as a motorcycle then all is good because AFAIK in Canada and the US, a motorcycle only needs to have 1 brake to be legal.


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## frodus (Apr 12, 2008)

If you use two motors, you EITHER need 2 controllers (one for each).... or you need a high voltage controller and put them in series. 

Paralleling these motors is not a good idea... The current will not be matched to each motor. If one starts to heat up more than the other, or doesn't have a matched impedance, it will use more current.... more current, more heat... and the problem worsens. If one motor fails, the other motor current could be twice what it normally is... and could burn the motor up.


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## toddshotrods (Feb 10, 2009)

tacitdream said:


> ...I couldn't find a controller that could do regen and had a 24-72V range. The best ones I could find were 24-48V... it seems like that would cramp my style a bit, so I've given up regen. Have you found a different suitable controller? Or are you going to limit yourself to 48V?


Kelly has controllers that do regen up to and beyond 72 volts. I might be using one of their 120v models.


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## order99 (Sep 8, 2008)

If I were considering a Tadpole Trike i'd most likely go with one decently-powerful motor on the rear wheel-from a design view it's just easier.

But if you have your heart set on two motors (and the increased complexity) why not place one on each front wheel for a FWD? With the front wheels doing all the pulling you would gain increased handling and traction. Mind you, hooking a single motor into an existing FWD axle/transmission would give you the aforementioned handling benefits AND the simpler design...what size were you estimating for your Trike BTW?


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## Jozzer (Mar 29, 2009)

If your going for pancake style motors, then I'd suggest the Agnimotor over the Perms. The Agni 95 will take over twice the current and up to 6000rpm, and is reinforced so the armature wont break up (happens very easily on the Perm).


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## fritzgutten (Jul 4, 2009)

if you're worried about running dual motors and dealing with their differences check out theworkshop.ca he's done a dual motor motorcycle conversion and deals with timing differences between his motors...might give some ideas about tuning as well as connections.
and if you run 2 motors in series on the front, you wont have to worry about a differential, the motors will automatically differentate their speed for you. but you'll be missing quite a bit of power with that wiring scheme. you could just connect one motor to each side, not physical drive connection between.

tacitdream - are you going to use some sort of computer control or feedback design to control those motors? it will most likely be hard to do tank style steering at any decent speed.


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## frodus (Apr 12, 2008)

1 controller per motor right?

Whats the Atmega going to be used for? The kelly RS232's are NOT isolated... and you'll likely fry your laptop port or your atmega unless you isolate it somehow.

I don't think the kelly samples at "10's of thousands" of times per second... anything over its sample rate would be overkill.

Keep us posted with the BMS and monitoring system though, sounds like an interesting system... but as an engineer, I see lots of details that are often overlooked.


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