ARC AAA & AA on li-ion

been overdriving li-ion in ARC AA's for sometime with no problems. Now that AAA li-ion are available it's a logical progression.

using li-ion in ARC AAA and AA seems to overcome the low voltage startup issue. but jury of effects on longivity is still out.

Very few ARC AAA's with chip problems actually got shipped. Most instances of intermitten problems I've seen are actually caused by bad contact between board to head and/or battery leakage.

AAA sized batteries seems to leak more than any other alk cells. don't know if that's true or not, but that what it seems like.

it doesn't take but a tiny leak to cause corosion and contact problems. film can be almost invisible. take a flat bladed screw driver and scrape post.

one of the few weakness in ARC AAA design is the negative battery post. note it's not a flat post, but are concave. This means only a tiny edge actually makes contact with cell.

ARC AAA with chip problems can be fixed by using AAA sized li-ion cells. I've had no problems over-driving ARC AAA and ARC AA's with li-ion so far. your mileage may veri..

using li-ion in ARC AAA with suspected chip/contact problems will usually fire up and run fine. brightness of course greatly increases. Have no idea of what this does to longivity, but if you are having problems already..

need to do more testing with regular ARC AAA to see if using li-ion in ARC AAA reduces life.

most of my testing with li-ion cell is with 14500 and ARC AA. they both use the same circuit, so tests should be valid to both.

don't blame me if you blow up your ARC AAA or AA.

CY,

Will there be any heat related problems? Wondering what is the current feed to the LED also.

Tested on a d'mo modded ARC aaa with acrylic lens, it get hot to torch pretty fast. Wonder if the die of the luxeon will burn out under prolong usage.

Stock
130mA at 1.36V Input = Led Current 44mA

AAA Li-Ion
300mA at 3.63V Input = Led Current <font color="red">245mA</font>

Nichia vf around 3.32volts.

Very angry blue bright! /ubbthreads/images/graemlins/ooo.gif

Wack, if those numbers are true koala (which i assume they are), you are whacking more current to the leds than what they are able to bite Cy. really brave indeed /ubbthreads/images/graemlins/tongue.gif

Personally, i would not suggest this. Something that is intended to be used with 1 cell should be used with 1 cell onlee and at that same voltage. I believe peter (gransee) has tried to run his Arc AAA from 2 AAA and found out that it is too hot after couple mins and does not recommend it at all.
Now, you are running it at an equivalent of 3 cells? /ubbthreads/images/graemlins/ooo.gif crazeee

[ QUOTE ]
Luxbright said:
Tested on a d'mo modded ARC aaa with acrylic lens, it get hot to torch pretty fast. Wonder if the die of the luxeon will burn out under prolong usage.

[/ QUOTE ]

Don't do this! I burnt the chip and had to send it back for a rebuilt.

/ubbthreads/images/graemlins/popcorn.gif In the name of science, Go CY go. We are all curious about the outcome. /ubbthreads/images/graemlins/popcorn.gif

Ran 14500 fresh off charger @ 4.18V on ARC AA for aprox. 4 hours straight. had to leave will run longer later.

I have to believe that 245ma will decay the 5mm led fairly quickly. Spec is 20 ma, so this is overdriving 1000%. I would not recommend this as you will likely sacrifice your Arcs.

/ubbthreads/images/graemlins/eek.gif

I just tried both out /ubbthreads/images/graemlins/wow.gif. I only use these lights for short periods of time so I'll take my chance. /ubbthreads/images/graemlins/buttrock.gif

Wouldn't short intermittent use on Li-ion still damage a stock aaa? Just a little at a time?

so far no damage, but I don't like the angry blue tint. only advantage was using li-ion cells on problem startup ARC's.

Since Peter is warranting ARC AAA's again. that's no longer an issue.

Can anyone identify what the tolerances of the components in the circuit are and what it actually does with 4.2 Volts running through it? This way we could definitely confirm if running Li-ions at 4.2 volts is safe in ARC AAA's & AA's as I personaly don't have the inventory or the cohonas that cy has to be doing this.

Thanks,

Matthew


[ QUOTE ]
chimo said:
The unpotted circuit board.


Assembly with the new LED in place.




[/ QUOTE ]

From the first pic, I see one side of the inductor is chipped off. I had the same thing happen in an Infinity Ultra board.

Here's a thread where the potential effects were discussed by several very knowledgeable people. This could also be a problem in this case.

The chip off the inductor shield in this case is very small. It looks worse in this photo than it actually is. The internal winding on this shielded inductor is not visible - any effect in this case is essentially negligible.

Paul

Koala, is that 245 mA a measured number or something you calculated? If calculated, how? I'm just curious as it seems awfully high.

[ QUOTE ]
M_R said:
Can anyone identify what the tolerances of the components in the circuit are and what it actually does with 4.2 Volts running through it? This way we could definitely confirm if running Li-ions at 4.2 volts is safe in ARC AAA's & AA's as I personaly don't have the inventory or the cohonas that cy has to be doing this.

Thanks,

Matthew


[/ QUOTE ]

The boost IC is designed to proide 5V max 100mA, but the output voltage drops due to the internal resistance. When Vin is higher than Vout with li-ion and low Vf led, the ic stops operating and the power supply goes to led via inductor and schottky diode, sort of direct drive.

So the actual current flowing to the led varies greatly depending on the led used. I get various current to led from 40mA to 250mA with 5mm white and 0.7A with 5mm red led.

I consider pushing the electronic parts hard may be still workable though it would reduce the life of them. But the led is not going to be happy to take higher current and surely call it a day sooner or later. (More likely sooner!)

My local cpfer "John" has been running AAA on 10430 for about a month before the led went kaput.

-- dj

Measured with my fluke. Also read djpark post, he's also getting 250mA.