AAA Rechargeable Batteries

Britton30 said:

The MiMH batteries are the most tolerant of being charged all the time. NiCADs will develop a "memory" and run down before needed if charged all the time.
Unless you run them dead every day, it would be better to charge them on some schedule, say, every 3-4 days. I have a Logitech remote with 2 rechargeable NiMH AA's and I charge it once a month. It is always on a bit.

Some people think that NiCad batteries should be completely discharged now and then to prevent loss of capacity via the "memory" effect. This is not the case. To explain why, I'll discuss "memory", and what you can do to avoid it.
Most people think NiCad "memory" comes from recharging your batteries after only partial discharge. The folk lore is that the battery somehow "remembers" the smaller capacity that was used, and only allows you to use this capacity in the future. This is rubbish. This effect has never been documented in any consumer system, in certainly not in bike lights.
However people in the battery industry use the term "memory" to apply to another phenomena that NiCad batteries do exhibit, which is more properly called voltage depression. Voltage depression is caused by overcharging NiCad cells at a slow rate (typically, the rate given by cheap AC/DC converters provided as chargers by light manufacturers). Once the battery is charged, the additional energy being added to the battery is converted into heat, and the heat changes the crystal structure of nickle and cadmium alloys, producing a different kind of crystal that produces less voltage than the desired crystal structure. When the battery is then discharged, the presence of the bad crystals means that they voltage of the battery is lower than it ought to be. The result is a somewhat dimmer, more yellow light, where before they were whiter and brighter.
Please note that voltage depression only results from overcharging your battery at a low rate. If you overcharging your battery at a high rate, you will do irreparable damage to the battery.
There are two ways to avoid "memory". (I must admit that I hate the term memory as applied to voltage depression, because it has nothing to do with what most people think of a NiCad "memory", and because the battery isn't "remembering" anything, it has just been overcharged.) The best way to avoid it is to get a charger that doesn't overcharge the battery, namely a smart charger that switches to a very low current when it detects that the battery is full. See here for more info on smart chargers. Halogen-Bulb High-Powered Bike Lights

I've only got AA rechargeable which I use in my camera. They are Energizer ones and the charger is the same make, it takes about 15 minutes to charge, there is a red light when you first start to charge which turns to green when the batteries are charged. The charger takes AA and AAA. Trouble is I don't use the camera enough so you can bet each time I want to use it I've got to charge the batteries before I can.

The only headphones I have don't need batteries they were cheap ones and just plug into the computers front jacks.

seekermeister said:

Pebbly,

That is an interesting explanation, but it brings to mind my earlier days in aviation, in that it was necessary to periodically deep cycle the batteries on aircraft with Ni-Cad batteries, to prevent memory issues. The aircraft batteries were not being overcharged, and the system that regulated charging was not in any way "cheap". Therefore, I'm wondering about what the source of your perspective is, or if you can document it?

Here you go seekermeister Halogen-Bulb High-Powered Bike Lights :)

seekermeister said:

Myra and Simon's personal website? I have no idea of who either of these people are, or how qualified that they may be on the subject. Do you have an academic or technical source...one that is not simply promoting a product that they are affiliated with?

I only found the info by searching Google but reading the credits for the NiCad info it takes you to the original author Sci.Electronics FAQ: NiCd Battery FAQ hope that helps to provide more info :)

Extend battery life: Conserve battery power on laptops, notebooks, and netbooks

This is from microsoft about Laptop Batteries Just incase it helps

I think they are both saying the same thing , The Sci.Electronics team use of technical jargon can be quite off putting but it still does not give any tangible evidence that can be stated as fact