Technical savy help needed!!!!!

Howdy,

I have a lot of lights that use the AAA battery cage. This is proving to be a source of frustation for me. When using any battery format, whether it be carbon-zinc, alkaline, ni-cad, or ni-mh, the lights work great for awhile and then dim down. The lights should burn with useable light for anywhere from an hour to 50 hours. So, when they start to decrease in brightness after only 20-30 minutes of use, it's frustrating.

Here's the question:
When checking the batteries (all types), there is always one battery severely discharged, while the other two remain near peak voltage. For instance, on a 9 LED light, I just pulled the cage and checked the voltage on each battery; 1) 1.51v, 2)1.49v, 3)1.01v (these happen to be carbon-zinc). Now, with my ni-mh batteries, I thought perhaps I had a couple of bad batteries, and marked them with a sharpie. After charging, their voltage is similar to others alike. Placed back in the cage, and running the light, now, another battery will discharge while its partners remain at peak voltage. Why is this happening?

If I'm not mistaken, the cage merely is a compact method of storing the batteries in series. If the batteries are in series, it seems logical to me that all would discharge at a similar rate.

Again, this seems to happen with all battery types, new and used, and in several different lights and configurations, so someone please explain to me the whys and wherefores of electrical theory, rules, etc.

Thanks in advance!

73

Anyone?

That really makes no sense to me, that one would be drained while the others still have close to starting voltage.

All I can guess is, you're mixing brands of batteries, or types of batteries within a brand if you're starting with all new batteries. You're starting with all new batteries, correct? I hope you're not assuming that one brand of carbon zinc or one brand of alkaline will drain exactly the same as another brand of either?

Also, capacities tend to vary between brands and even in different types of the same chemistry within brands. Say Energizer Max compared to Energizer Industrial as an example. Energizer Max AAA batteries have about 900mAh capacity, while the Energizer Industrial AAA's have about 1250mAh capacity apiece. Both are alkaline batteries.

All I can say aside from that is, AAA batteries make a very bad source of energy for 1W Lux and above flashlights, because of their low capacity. The 20 minutes then dimming will be the rule rather than the exception. Two typical alkaline AAA batteries will have even less capacity than the typical alkaline AA.

Also, carbon zinc batteries are not a good energy source for flashlights. They are best for low drain applications like radios. They are also good for devices that are low drain and sit a long time without being used because carbon zinc batteries don't tend to leak or lose their voltage over time like alkalines do. At least in my experience. That's where the whole "Heavy Duty" marketing thing comes from.

Don't know of an electrical reason why the middle battery is only draining.
Check the obvious first.
I've also several 3AAA battery carrier lights. And the construction of the carriers vary. Some are really lousy.

Is this happening only with one light? (the 9-led)
Inspect its construction. It may have a bad solder joint or high spot at the positive end. Some carriers have exposed conductors that may accidentally contact a part of the light and short out that one battery.

Make sure the batteries are charged properly. Let freshly charged cells stabilize for 24 hrs and measure their voltage to see if a cell is internally shorted.
Since the cells are numbered, run down the cells in the light and note each cell's voltage. Recharge and rotate the cells to see if only that middle position yields low voltage.
If so, then inspect the contact paths from the middle cell. I bet you'll find it may have a conductor touching the barrel, or a positive end solder blob.

thanks so far for all the good tips.....

Let me explain again. I started out with all new cells-ni-mh 950mah fully charged. This unusual situation manifested in a "1 watt" led light. Upon dimming, I checked the voltage of each of the 3 batteries. Only one was discharged. I marked it, and replaced with 3 newly charged batteries. Same thing happened again. Now, I've tried freshly charged ni-mh and nicads. I've tried brand new and known to be good used. I've also tried brand new alkalines, and carbon zinc. Same problem. This problem is exhibited in 10 different 9 LED lights, 3 3watt luxeon lights, and a 1watt single led. Every light I have that employs a battery magazine! The three different models of lights employ different types of battery magazines, but all have springed negative battery contacts within the cage. It seems to be position impervious within the cage as well. Each magazine is wrapped with paper to ensure no rattle, and no shifting out of position for the batteries.

Each light has been gone through- that is to say, contacts have been cleaned, solder joints have been inspected and resoldered to ensure no cold solder joints, threads and contact points have been cleaned and/or filed to ensure contact.

What gives?

Am i to understand correctly that in your experimentation you have run across all 3 of the following conditions regarding battery position in the carrier:

Condition #1:
Battery 1 (Low) --> Battery 2 (Normal) --> Battery 3 (Normal)

Condition #2:
Battery 1 (Normal) --> Battery 2 (Low) --> Battery 3 (Normal)

Condition #3
Battery 1 (Normal) --> Battery 2 (Normal) --> Battery 3 (Low)


Low = lower voltage reading than the other 2 batteries
Normal = expected voltage reading

This has be perplexed as well. I googled a lot of information and i can find no technical/scientific reason why this should occur. This is definantly NOT normal or at this point explainable. But suffice it to say that with as many different torches that you've experienced this phenomenon with i'd say it definantly merits some CPF brainpower.

PS: what device are you using to test the voltage? Is it a VMM or a true battery tester that can measure capacity under load?

:thinking:

I'm thinking that your carriers are not all the same and neither are the battery positions. It is important for the resistance of each position in the battery carrier to be the same. If it isn't then the position with the least resistance will drain first - which is what you observe. Each carrier may have a different position which is the minimum resistance.
Try marking for each carrier which position the discharged battery is found in. Repeat the experiment enough times to either prove that the same position is the problem in each carrier or not. If it is, then you need to somehow figure out how to match the resistance for each position...not sure this will be easy.
Sam