Arc AAA - just voltage step up, no regulation !

I just bought my ARC AAA. However when I measure the V/I curve, it seems that the circuit inside is only voltage step up but not voltage regulation. My measurements are :

V=1.50V I=240mA
V=1.41V I=240mA
V=1.33V I=230mA
V=1.27V I=180mA
V=1.21V I=140mA
V=1.15V I=95mA
V=1.07V I=77mA
V=1.00V I=73mA
V=0.91V I=60mA
V=0.82V I=55mA

This V/I curve showed that the input power goes down as the voltage. The light output should also go down as the voltage.

In a true voltage regulating step up circuit, the output voltage to the LED (which I cannot measure as it is sealed) should keep constant. Input current should increase when input voltage decrease, this is to provide same power to the output. Usually input power goes up slightly as voltage goes down, because efficiency is worse at lower voltage.

Without a regulating effect, the LED flashlight cannot keep constant light output while the battery voltage drops.

I don't have a meter to measure the luminance. Can anyone tell me whether you observe the luminance drop as the battery run out.

I want a Flashlight with TRUE constant light (with regulator circuit). Does any ARC flishlight produce constant output during most of the battery life ?

Any other measurement on Arc AAA is most appreciated.

You could have saved yourself a bunch of time by just asking. The ARC-AAA is partially regulated. Look in the REVIEWS forum of CPF and you see the runtime graphs clearly show the light output drops with each minute that passes.

James,
The Arc LS is current regulated, the Luxeon receives 330mA for most of the life of the CR123A battery. The Arc 5mm lights use more of a voltage booster that is partially regulated. Word on the street is you can't notice the light dimming until it hits the 50% dimmer point. This should occur after 5 hours of use.

so is the circuit in an arc AAA voltage boosted, and partially regulated, or just boosted without any regulation?

Re: Arc AAA - just voltage step up, no regulation

Go here
for Peters explanation on this very subject.

Mike

Re: Arc AAA - just voltage step up, no regulation

Hello Jameswong and welcome to the CPF. I appreciate your enthusiam! You seem to know more than the average bloke about electronic circuits.

My fellow members have already provided an excellent explanations. The link provided by Mike is for a good thread on the subject. There was another thread posted recently here.

CPF'er "Quickbeam" posted the following runtime graphs (I believe these graphs are a results of CPF'er "Roys" tests :

Here is a light with a nice flat regulation:



This is the Pal light. It is not the smallest light around nor is the brightest. It also uses a higher voltage battery (9v) than most. But it has flat regulation!

Here's a light without any regulation, the "CMG Reactor":



It is being powered by alkaline cells and has no regulation whatsoever. Notice this rather large light only lasts about an hour before it has lost 50% of it's brightness. This from 3 AA cells!

And here is a partially regulated light, the Arc-AA.



I say, "partially regulated" because it is obviously a mix of the above two waveforms. The light is not completely following the discharge curve of the battery nor is flatly regulated either.

However, the Arc-AA provides a bright light from a very small input voltage (on less voltage than the other two examples. Notices it takes about 10 hours for the light to loose 50% of it's brightness powered by just a single AA cell.

If you read the link provided by Mike. I go into why partial regulation is better in some situations.

Peter

Re: Arc AAA - just voltage step up, no regulation

Yup, those graphs are Roy's. More can be found HERE for reference.

Re: Arc AAA - just voltage step up, no regulation

This is a double thread, please reply to the an other, Not this one.

Thanks

I've closed this one for you, James. - Empath