Juha

Update: none of my current 5-6 rechargeable NiMH AA-pairs give me anything close to 2hrs of burn time (turbo mode). Recharging them right before use seems to be a must. I now have a couple of hybrid NiMHs as backup, as they don't discharge so quickly. I can have them in the bag for days and still be confident they'll last all the way home.

--J

Photosmith

How funny, there was just recently some testing done on another forum with NiMH rechargeables and freezing (or near freezing) temperatures.

Testing of NiMH rechargeables at 36F / 2C

Bottom line is that Powerex 2700's were tested by one member and Sanyo Eneloop 2000's by another member and they still produced 85-90% as much energy output at near-freezing temps as they did at room temperature. NiMH is rated to about -20C (-4F) so to see two different brands still performing so well at just above freezing was actually somewhat surprising.



As for self-discharge rates, self-discharge is rated at 12% in the first 24 hours, then about 12% a month after that. The low discharge cells are better, with the Rayovac's rated at something like 15% in 3 months, and the Sanyos at 15% a year.

Cyclist0383

What are your current batteries? Have you changed them since your OP? I use Sanyo 2700, and during the few days it was cold this winter I got well over 2 hours of run time.

Juha

Ziemas, I still have the same batteries as when I started the thread, but I did buy the hybrid ReCykos I mentioned in post #20.

I took my time trying my old batteries out in actual use to see how they do. I also measured on-the-shelf voltage drops while I was at it. My old no-brands lost 8-9% of voltage during the first 12 hours, and 13-14% in the first 24hrs. Brand names did marginally better. Hybrids (GP ReCyko) were up to their marketing in this respect, barely 0,5% voltage drop during that time.

It's been an interesting exercise. Most likely I'll get some Sanyos or other brand name, hi-capacity NiMHs and use those as my primary batteries with the Fenix. Hybrids will stay in the bag for backup, as their self-discharge rate is low enough to guarantee they're actually up to the task when needed. I don't mind the shorter burn time with them, they're only there to get me home. Old NiMHs will go in my backup light, rear leds and such.

--J

balto charlie

Hey J: I posted earlier that I had no problems w/ my Fenix, the cold and NiMH batteries. Well all of that has changed recently. A few weeks back I rode for a few hours in cool temps(40F, 5C) with the light on flash mode. When it came time to switch to high it died. I figured batteries. I returned home charged all of my batteries for the AM commute. Temps dropped to 13F/-10C. That morning the light worked for less than an hour. I recharged them again then I realized that the overall brightness was no longer there, lost all modes other than high(but not as high as before) and flash. All lower levels gone!!! I know my batteries are good as they light other lights well. Run time is much shorter and brightness reduced. I never bang my light around. I am contacting Fenix to tell them the problem. Perhaps these light are a "1 year only light". FWIW: I ride almost everyday, run the light 1-2 hours per day; so this might just be it life expectancy. Charlie

Cyclist0383

IIRC lower levels gone on a Fenix light indicate a problem with the batteries being too weak. Exactly what batteries are you using and do you have a way to test to voltage in them?

You could try posting a CPF too; those folks are both very knowledgeable and helpful.

https://www.candlepowerforums.com/vb/...isplay.php?f=9

balto charlie

Really. The batteries work in another light pretty well. The batteries PowerX 2700 ,AA, NiMH rechargeable, purchased Nov07. I do ride almost everyday but alternate between 2 sets of batteries. I contacted Fenix and they said sounds like something is wrong and to return them. They really answered my email immediately. I'm impressed. But if you say batteries I will buy a set of disposable AA, brand spanking new to test out. I can't see how both sets of my batteries showed the same problems at the same time. Thanks charlie

Cyclist0383

I'd trust Fenix over myself any day!

Are you using freshly charged batteries when you are having the problem?

balto charlie

I almost always charge my batteries daily. Yesterday I used new off the shelf disposables and still no low light levels and overall brightness is down. I'm sending it back to Fenix. They were really great in responding to my request for help. This company is excellent. Will report back after I hear from them. Charlie

2manybikes

As they say in the instructions, you need to keep the contact surfaces clean. This includes the threads, they use them to pass current for the light to work. Also the ends of the barrel where it touchs the head and the end cap. Dirt or grease on the threads or flats can cause a problem. Even invisible corrosion from being outside can do this. Just a couple of ohms can be a problem with low voltage stuff like this.
You also need to carefull clean the contacts with a Q-tip and a little alcohol. (All this is in the instructions).

I have saved watches, calculators and other small things just by wiping the contacts with a flannel shirt and they kept going for a long time. It also works great on small bike lights, like blinkies.

The corrosion can be almost invisible, or if you look close you can see it, just a little discoloration. Even thought the lights are water tight they can get condensation inside them in the winter from going inside and out. This can corrode the contacts. The symptoms you describe fit this perfectly, it happens with all kinds of things, it's very common. If you use it in the cold (as you do) you need to stay on top of this.

This is an on going thing, not a one time problem, you need to clean the contacts, threads and lands periodically, especially in the winter. Your symptoms sound perfectly normal and typical to me. Nothing unusual. I can't believe this has not already come up, did I miss it?

balto charlie

I just tried your advice. I cleaned the contacts at both ends, threads, battery ends w/ ETOH and Q tips. I even used a microscope to see how dirty/clean the contact points were. The threads were dirty, contacts not bad. Cleaned them all anyway. I turned off the room light and fired up the Fenix. I compared it to my bike halogens. Halogens won. When the Fenix was new the halogens lost. The batteries have 30 min run time on them so will test with fresh batteries tonight. I also tried the low levels on the Fenix and saw no light until I looked directly at the lens. There was one low level but it was so low that it did not show up on the wall in a dark room.
When I removed the lens end to clean I looked at the contact at the base of the lens. It looked OK but around it was a green background with 4 or 5 solder looking areas. 2 or3 had what looked to be solder(silver) in them and 2 areas (brass) were not filled in with this silver stuff. This may mean nothing, just an observation.
Thanks for the advice. I really was hoping it would solve the problem. I was hoping to make it to the end of winter w/out sending it back. I could ride 'as is' with less power but will opt to return. I really like the strobe at twilight. The way it lights up the signs is so cool. It still lights 'em up but not as brilliantly as before. Charlie

2manybikes

If you were riding with NimH batteries at 13 degrees F and you got short run time, then everything is normal, that's what you should expect. When they get warm they will be back. Don't try and charge them if they are cold.

Did you check the batteries with a volt meter at room temperature? What kind of voltage are you getting? If You can get a meter easily you might as well check them before shipping it back.
Nimh have a fast self discharge rate. If you waited a day from when they were in the other light that might be the difference. Especially if they are on the way out. If the other lights don't use as much current as the Fenix it is possible that the other lights will work, but the extra draw from the Fenix could be too much for a weak battery.

Rechargeable batteries do wear out. Did you ever try to calculate the number of use cycles on them?

agarose2000

Send it back, plain and simple, and get them to send you a new one. I can't believe how painful your posts make the FENIX sound.

It's one of the simplest pieces of tech equipment I have. I dump in NiMh batts, bring a spare set if I'm out for 2+ hours, and I'm good to go. Fabulous lighting all the way.

Get a new one, and try out your various batteries. ALL of my batts work, from the 1800mA thru the 2400mA, and the runtime does seem to correlated extremely well with the extra mAs on the higher capacity batts. I'll bet the customer service will be pretty good at Fenix as well, from what I've seen from other posts.