Just toying with an idea... Electric "boost"

[Sonreir]

So yeah... I like electrics and electronics.

I also like going fast.

Been messing with the idea of a hybrid bike for a while now. Not with the goal of reducing fuel consumption, like many hybrid vehicles, but more like the F1 approach of providing a short boost of power.

Enter the Agni motor (aka Lynch motor). It's a high efficiency brushed DC motor capable of 90% efficiency. With a 48V source, these babies can put out about 22 horsepower at 3500 RPM and weigh in at less than 25 pounds. The downside is that it pulls about 400A.

Here's the thing, though. LI-ION battery technology is really coming along. They're small and light and can deliver huge amounts of current. In fact, four of the earthX ETX6 batteries, run in series, can provide the voltage and current needed to run this motor for almost a minute. And those four batteries, together, weigh less than four pounds and contain automatic cell balancing electronics and an automatic cutoff if they drain too much.

So I guess that just leaves mounting up the motor to the final drive and wiring everything up.

22hp boost for under a grand, anyone?

 

[carnivorous chicken]

Interesting -- but how to tackle the "competing" drives? In other words, where will the electric motor attach to drive the wheel? Wouldn't that boost of power, if it was part of the chain/sprocket drive, then simultaneously force the pistons to move faster than their air/fuel/spark intake would dictate?

 

[Sonreir]

Not necessarily.

When the electric motor takes on some of the effort of moving the bike, this allows the engine to rev more easily. It like revving the engine in neutral: It's super easy because there is less load.

 

[Grazz256]

Yes, this seems like a great idea.. If you need a beta tester for a future kit I'm in

I think you'll find that that motor spins a bit slow for what you want to do at 48V, something like this might be a bit better
http://www.thunderstruck-ev.com/motenergy-1302-water-cooled-brushless.html

the downside of these BLDC type motors is that you'll need a fancy controller, but you can get controllers that do recovery charging on braking.

Cheers

 

[Sonreir]

Well... 3600 RPM should be good enough for the final drive, I would think. 124 MPH, by my calculations.

 

[TomTerrific]

I'd like to see the electric motor driving the engine. This way the electric motor could be used as both the charging and starting systems as well as a boost of power.

I've always thought a hub motor would make a good sidecar wheel. Set up with care, the hub motor would provide both acceleration and braking to help with the sidecar weight.

Tom

 

[Sonreir]

Tom,

The sheer amount of weight required to do a hybrid drive on a motorcycle pretty much precludes it from happening. The MotoCzysz E1pc (winner of the TT Zero several times) requires 200 pounds of LI-ION batteries just make it forty miles. Now add an engine to that and we're looking at another 200 pounds? You'd end up with a half ton bike.

 

[cosworth]

Can this motor act as a generator to charge the batteries? If you want F1 style implementation, make the motor engage when braking is applied to charge the system. Just like KERS.

 

[Sonreir]

Can this motor act as a generator to charge the batteries? If you want F1 style implementation, make the motor engage when braking is applied to charge the system. Just like KERS.

Not sure yet. Placement of the motor is going to be pretty important, though. I'm wondering how things would act of the motor is setup for braking as well. I'm assuming that placing it on the leading or trailing side of the chain will definitely matter.

 

[cosworth]

Electric clutch like one from an automotive A/C compressor? Have a second sprocket and smaller chain to mount it somewhere close?

 

[Sonreir]

Possible. I really don't know yet. I might have to experiment with a few different combos.

 

[Thomas_Hudson]

How about a bike with shaft drive? Can the drive assembly be added inline ? Come right off the output shaft so you can add your boost at any rpm level? Start charging at cruising speeds. Or would the packaging be a nightmare?

 

[Sonreir]

Interesting idea. I imagine the mounting would be a challenge and the motor would need a shaft running all the way through it, but it could work.

 

[Thomas_Hudson]

How about a bike with shaft drive? Can the drive assembly be added inline ? Come right off the output shaft so you can add your boost at any rpm level? Start charging at cruising speeds. Or would the packaging be a nightmare?

whoops. Never mind. This might be the worst idea I've ever had. On the drive side could get you killed if the electric motor goes wild. This can only work on the engine crank shaft , so you can squeeze the clutch if all hell breaks loose. Many appoligies.

 

[Sonreir]

Same problem if you mount anywhere on the final drive. Just sayin'.

Hopefully, "motors gone wild", isn't real.

 

[Thomas_Hudson]

I just thought more about it and the thought of say a selanoid sticking, or a wire shorting, or circuitry getting compromised, scared the hell out of me. Thinking that 22hp gone wild is more than the rear brake can fight, and say going into a twisty the switch fails....... Stuff could get hairy. Atleast if you can squeeze the clutch you could regain some control. Maybe.
I'm no engineer and I should learn when to JSTFU. Sorry, I thought it was gold for a second though.

 

[Sonreir]

Definitely something to consider. There are things that could be done to decrease the likelihood of there being problems, but hopefully a decent controller would have some fail safes.

 

[Thomas_Hudson]

I just didn't want someone to read my post and think "Great idea. I'll just weld a chevy starter to my drive shaft." And go kill themselves.

 

[Hurco550]

Very interesting.. I don't have much constructive to add, but the shop was to cold last night to work on the bike. I happened to stumble upon the documentary called "charged" last night on Netflix about the electric bikes running isle of man. Very amazing stuff! Following along.

 

[cosworth]

Well the idea of a robust electric clutch seems valid here. Looking at the majority of KERS systems, it's kinetic advantage is the reduction of parasitic loss. So disengaging from the drive seems key to not abusing any thermodynamic laws. lol.