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Old 02-14-2015, 07:20 PM
nayr83333 nayr83333 is offline
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Default Flywheel?

I understand that adding a flywheel can increase range on an EV. How? Flywheels just store energy, they can't make it. Are people around here using flywheels? If so what are your results. I have a 30lb wheel that I took off my mortar. Should I put it back on?
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Old 02-14-2015, 08:18 PM
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I know nearly nothing about EVs. But- knowing how a flywheel stores energy- wouldn't it mean the ability to have longer "throttle off" or "coast" periods?

30lbs? Got a picture of this beast?
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Old 02-14-2015, 11:36 PM
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Electric motor.

You should coast longer but any energy released from the flywheel had to be first put there by the batteries running the motor. Since that storage device can't be 100% efficient, there should be even more loss. Not gain. I know it works, I just don't get it.
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Old 02-15-2015, 03:05 AM
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a flywheel in ev assistance works different than one on a combustion engine..

and indeed it CAN add mileage or power.. maybe both..
but if not set up correctly it will do just the opposite,
reduce available power and mileage (dead weight)...

Okay, a common set up is mechanical regenerative breaking
braking engages flywheel "charging" it with as much momentum as possible
as soon as the momentum of the flywheel is greater than the momentum of the kart,
it will disengage (start to freewheel).
the next time you accelerate, the flywheel then provides it's momentum to either add power (faster acceleration) or reduce powerdraw (same acceleration, less drainage of the batpack)

A second possible method is coaster charging,
same idea, but the flywheel will charge as soon as you release the throttle.
on flat tracks that's a good alternative actually.
The flywheel will reduce coasting a bit, but since it's fully charged most of the time, that won't be too much,
and you can accelerate without drawing too much juice from the batteries

both methods require a big deal of mechanic and electronic gear.
you want the flywheel to spin fast.. really fast.. 4k rpm or more; so it needs to have low friction bearings.
And you want a controller that reads your throttle (brake) the rpm of the flywheel etc.
Just to judge if it should provide power or should be loaded.
and an electric clutch, which isn't cheap I'm afraid

And in the end.. it's 30lbs of additional weight (likely 40 lbs with mounting and controller...) which, let's be honest WILL reduce mileage, and acceleration by a good amount.

If in the end, the flywheel can compensate for that initial loss; IDK.
Depends on how well it's set up.

What I do know is, that many formula 1 teams tried, and none succeeded with mechanical flywheels..
The one mechanical flywheel that I know is left is the Porsche one.

Do not underestimate the power a 30lbs rotating mass has...
The angular momentum alone will affect your steering behaviour!

So coaster charging might turn out to feel nasty on a kart with a flywheel that heavy.

Anyways.. I'd like to see a DIY approach, but personally I wouldn't;
I'd rather set up electric regenerative breaking and call it a day ...
much simpler to do.. much less weight to carry.. (i.e. no initial loss)
and thus a guaranteed increase of mileage (no power increase though)

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Old 02-17-2015, 06:40 PM
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Quote:
Originally Posted by Doc Sprocket View Post
I know nearly nothing about EVs. But- knowing how a flywheel stores energy- wouldn't it mean the ability to have longer "throttle off" or "coast" periods?

30lbs? Got a picture of this beast?
You are right. It's nowhere near 30lbs, more like 10. I don't know where I got 30 from. Probable the motor with flywheel.

My flywheel is mounted on the opposite side of drive shaft. I'll probably try it both ways and see what feels better.
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