ARC LSH-P dims quickly on AA's

ARC LSH-P dims quickly on AA\'s

I've owned this for a while, but never left it on for any extended period. Recently I wanted to see how long it would burn on fresh 2300 MaH NIMH's. The light dimmed suddenly after about 5 minutes.

Thinking it was the batteries, I put in a pair of new alkaline AA's and the same thing. Next, I tried new lithium AA'a-same result.

Finally, I replaced the AA's with one CR123 and the problem goes away. What's up with this?

Re: ARC LSH-P dims quickly on AA\'s

Problem with your Kroll? bad contact somewhere increasing resistance? Try taking the switch out and shorting the AA battery to the body.

Re: ARC LSH-P dims quickly on AA\'s

Thanks, I'll give that a try. I also noticed last night that it does the same thing with the CR123 after all.

Re: ARC LSH-P dims quickly on AA\'s

Now that I think about it (duh!), I have been switching between two different bodies (123 vs. AA) which have two different Krolls. So it must not be the Kroll, correct?

Also, an older ARC LSL-S doesn't have this problem when used with the identical bodies and Krolls.

Re: ARC LSH-P dims quickly on AA\'s

I also noticed that when the light is turned off for a few seconds / minutes it comes back on at brighter level. It's almost like it is overheating and stepping the brightness down to protect itself.

Re: ARC LSH-P dims quickly on AA\'s

[ QUOTE ]
nerdgineer said:
Problem with your Kroll? bad contact somewhere increasing resistance? Try taking the switch out and shorting the AA battery to the body.

[/ QUOTE ]

I think nerdgineer is barking up the right tree. to much resistance some where. Could be in the head somewhere. Like possibly where the board is grounded to the body. Some where there is to much resistance. Must find where. Good luck.

Re: ARC LSH-P dims quickly on AA\'s

I've had 3 Krolls and varying amounts of rotten luck with all of them. They are just crap.

Re: ARC LSH-P dims quickly on AA\'s

I followed-up on Nerdgineer's and ZuluWhiskeyFox's suggestion. When looking inside the head of an older LSL-S (that works great), I noticed that there is a black washer. This same washer is not in the LSH-P troublemaker (what I see is an exposed copper wire around the circumference of the head).

So I tried fresh batteries and screwed the LSH-P on only enough to allow the light to come on. I noticed that the head doesn't get hot at all like it used to (it was almost too hot too hold).

If a missing washer is the problem, does anyone have a spec for this or will any old washer that fits do?

Re: ARC LSH-P dims quickly on AA\'s

Further along the lines above, I speculate that the troublemaker's copper wave washer under the head's lockring may be corroded or coated with some loctite. That may be the copper wire you think you see? If it were mine, and discounting both sets of batteries and Krolls being bad, or a dirty contact or threads, I would open up the head. You need a lockring removal tool. Some come out easy, some are loctited very tight, so the tool might need be a simple pair of tweezers, or you might need a big vise and a custom pin tool. I clean the circuit board ground trace and copper washer of all traces of loctite, wipe with Caig DeOxit (an electronic contact cleaner), and reassemble without loctite. Then you have to be prepared to recenter the LED during reassembly.

Krolls are not great, but usually work OK if they are cleaned.

Re: ARC LSH-P dims quickly on AA\'s

Do you know that when LED heats up they become dimmer and dimmer? I hope you are not having a thermal problem.

Re: ARC LSH-P dims quickly on AA\'s

This may be a bit obvious, but it's escaped me a few times. Have you looked at the battery contacts? If they're exposed ever to a bit of moisture they like rusting. Especially if exposed to moisture and current.

I've also had the anode of the battery covered in gunk before, and had the contact on the board covered in stuff as well, making for high resistance along that connection. A bit of acetone on a Q-Tip usually cleans everything up well.