Replacing the battery with capacitors

Frog,

I am not sure what kind of power draw you would get out of the starter, offhand. But, yes, in theory, the caps would work fine. I would assume you would need to add a resistor after that thing so that you don't blow up your starter.

Also, you should be able to connect the charger circuit up to the caps too. This would mean the caps would be charged when you stall, and would restart the motor. This would act in the same manner as the battery, for as long as the RC constant is, of which you would need to figure out. This would determine how long you could crank the motor before recharging the caps. I'm curious if there is a setup out there to do this.

Anyway, if you lose your charge, then you are kicking, that is the real difference. I'm not sure how the circuit would pan out on this, but an EE could probably do it for you pretty easily. Another thought is that a 4.7F capacitor is a pretty dangerous thing, so beware of playing with these toys.

Froggy, you should check out this bling. Yeah, I said it.

But, with all that said, just buy a nice battery and do the fancy quick-connect under the seat to a charger, I think it would save weight.

-Parsko

Starts and runs well eh Frog?

Funny enough the carburetor I recently modified for you came off of the 2001 blown up 470 mentioned in an earlier thread.

Oh, of course, the capacitor. 56,000 μF.

Being a computer guy you should recognize the following:


Dale

LeFrog said:

Yes, Dale, it starts really well, now, I think it was just how the screw were set, I guess.

Click to expand...

A "loose screw" attached to the throttle always seems to wreak havoc.

The capacitor is sold by many including Trail-Tech.

Best Regards,
Dale

LeFrog said:

When I used to do tech support on the phone (hard job, by the way), we would use a lot of homemade acronyms.

One was: "PEBKAC".

Meaning: "Problem exists between keyboard and chair".

But in my defense: "they're not easy easy to start the older Bergs".

Click to expand...

Such in general is an understatement.

Happy Riding.

Dale

Sorry to not get to it sooner but even the largest capacitor available is still about a billion times too small to crankstart an engine and even a few million times too small to run lights for any length of time. That is why there still is not much alternative to a battery.

When a capacitor is used to replace a battery it only "smoothes" out the DC pulses that come from the rectifier so that the electrical system works while the engine is running. It can only supply power to the electrix for the time it takes from one AC cycle to the next - perhaps 3 milliseconds. In that time it will lose about 10% of its voltage. It cannot be used as an energy store.

You can probably remove the battery & starter OK without worrying about a capacitor. The capacitor is really only needed if you use any electronic items on the bike such as a electronic turning indicator flasher unit. Hot wire flasher units - little aluminium cans - seem to work OK. The horn still works without a capacitor but sounds like a sick cow.

You can expect to see the lights go a bit dim at idle, but this usually isn't a problem and they work OK without a battery. Of course if the road rules in your part of the world require that the lights keep lit when the engine stalls (they tried to bring that in here 10 years ago but failed ) then you have no chioce but to fit a small battery.

I've had a KTM & a Husky with full road-legal electrics, no battery and no capacitor. I had another KTM that used an electronic flaher and was fitted with a 4700 microfarad @35V capacitor from the factory.