Where does excess power go in an unregulated system? LED's

andrew . /

Oct 20, 2021 12:08AM

So Im playing with LEDs toward an eventual turn signal install and im trying to puzzle out the basic function of the electrical system.

I get the idea that the generator produces X watts and you try to load up all your bulbs to match that output. But my KTM Foxi has a headlight on-off switch as well as hi-low beam. If you plan the load of the headlight bulb in your overall wattage, what happens when you turn it off? Those 10-20 watts need to go somewhere, even when the thing was new. So what kept it from blowing bulbs ahen the headlight was off?

I have an H3 LED headlight bulb that lights, but I've burned a few various bulbs in testing. I've left the halogen bulb as a wattage sink to save ths rest until I figure out a solution. I'm using several LED bulbs, 6-12v capable by design and they seem to hold up as long as the headlight is on.

Can I add a resistor somewhere to act as a power sink to use the H3 LED? My eventual issue is the digital LED blinker unit ive got seems to be rather power hungry, so I want to be able to give it as much power as it wants, but that would only be intermittent, so that can't really factor into the power load very well. Having a dump resistor would also steal power from the blinker, but maybe i could have the power to the resistor disconnect when the blinkers are switched on?

I think the easy answer is put on a 4 terminal regulator/rectifier but the LEDs I have seem to work fine without a rectifier and it's saving me the wiring hassle. I could go a regulator and skip the rectifier, but that's a maybe.

Re: Where does excess power go in an unregulated system? LED's

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brianf

Oct 20, 2021 01:36AM

A simple one wire regulator is what you really want. It will convert the extra power into heat, and prevent your bulbs from blowing.

In a typical generator, the rpm required to reach a particular voltage is a function of the load. The more power being consumed, the higher the rpm required to reach the target voltage. Moped electrical systems are different from a typical generator in that the rpm (and thus power generated) is a function of speed, not of the load wattage.

A generator with no load will produce no current (but high voltage), and a generator with infinite load (a short circuit) will produce no voltage (the current produced just heats up the windings, and can destroy them). If you reduce the load of a particular setup, your generator will produce a higher voltage for a given rpm. This is why so many folks running LEDs without regulators blow them out.

You might find this thread interesting: https://electronics.stackexchange.com/questions/327337/does-a-generator-produce-voltage-or-current

Re: Where does excess power go in an unregulated system? LED's

Dirty30 Dillon /

hydra

Oct 20, 2021 09:30AM

> Brian F wrote:

> -------------------------------------------------------

> A generator with no load will produce no current (but high voltage), and

> a generator with infinite load (a short circuit) will produce no voltage

> (the current produced just heats up the windings, and can destroy them).

> If you reduce the load of a particular setup, your generator will

> produce a higher voltage for a given rpm. This is why so many folks

> running LEDs without regulators blow them out.

This is a vitally important concept that most folks don't actually remember.

Re: Where does excess power go in an unregulated system? LED's

andrew . /

foxifox OP

Oct 20, 2021 11:32AM

So it sounds like running LEDs with a regulator would be better for the generator than running halogens? As long as the regulator isn't creating a massive load the low load from the LEDs would greatly reduce any heat buildup in the coils? Would this also reduce the engine power input required as per the article you posted? I'm not really concerned with that but I had the same sort of questions working on a Honda NC50 and I never really found a good answer. I figured the permanent magnet situation just created the same engine load at all times, it was just a matter of how the electricity produced was utilized.

As for a regulator, one of these guys?

https://www.treatland.tv/trail-tech-voltage-regulator-p/trail-tech-regulator-7003-AC01.htm?gclid=CjwKCAjw_L6LBhBbEiwA4c46usrltvucmhuJOVIax0RrgFGNVBOW_sJNUpYXC4HzQLL2jL6pLzaLyBoCR2EQAvD_BwE

Treats says 6-12v, but trailtech says 12v, and even the little treats picture says 12v?

Re: Where does excess power go in an unregulated system? LED's

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brianf

Oct 20, 2021 05:26PM

Engine power required to run lights, whether they are halogen or LEDs is trivial even for a tiny moped motor; like < 1%; you'll never notice the difference.

I recommend running a regulator with all 12v setups, it just takes all of the guesswork out of the problem.

The TT regulator you posted is an excellent choice. It does have variable output, but I'd bet you won't need to adjust it.

Re: Where does excess power go in an unregulated system? LED's

Dirty30 Dillon /

hydra

Oct 20, 2021 06:26PM

> andrew . wrote:

> -------------------------------------------------------

> So it sounds like running LEDs with a regulator would be better for the

> generator than running halogens? As long as the regulator isn't

> creating a massive load the low load from the LEDs would greatly reduce

> any heat buildup in the coils? Would this also reduce the engine power

> input required as per the article you posted? I'm not really concerned

> with that but I had the same sort of questions working on a Honda NC50

> and I never really found a good answer. I figured the permanent magnet

> situation just created the same engine load at all times, it was just a

> matter of how the electricity produced was utilized.

There's a lot of misunderstanding going on in this paragraph. The regulator will not put any "load" on the system, and you don't need to worry about any heat on a stock ignition. caused but shorted coil, unless you are hard shorting things.

Also using "load" in terms of engine load and electrical draw is probably not helping.

I've found that unless you are going to do a little work and upgrade to full reg/rec and jump to either caps or a battery, it's just simply not that economical to utilize LED's on an old moped.

Re: Where does excess power go in an unregulated system? LED's

andrew . /

foxifox OP

Oct 20, 2021 10:13PM

The regulator seems like a nice piece of equipment but Im running 6v, and its 6v ability seems wishy-washy. I ordered a yamaha one wire 6v regulator and see how that goes.

Re: Where does excess power go in an unregulated system? LED's

andrew . /

foxifox OP

Oct 20, 2021 10:14PM

I was considering that load was crossing over in a few places. The whole grand circle of this thing is just to get turn signals on the bike and theres not enough juice in the generator to do the job. So I need the LED turn signal bulbs to cut down that wattage. If Im doing that I might as well swap out whatever LEDs if I can.

I just went and ordered a Yamaha 6v single wire regulator and see what happens. There seemed to be some success using just that with LEDs on a stock 6v system, whereas the adjustable one doesn't hav any objective data showing it works for 6v. The honda NC50 I did before had a battery and recitifer, no regulator, and once I hooked up the battery it did its job and stabilized the voltage for the whole bike. So Im familiar with a small battery setup, and that was actually my original plan with this Foxi but it looks like I can roundabout the battery, maybe, possibly, if Im lucky. I don't mind burning bulbs, they're cheap enough and I'm not seriously riding the bike yet. Im just curious to find a combo that works. If I end up with a gel battery under the seat and reg/rec then so be it.

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