It all started years ago when Nickel Cadmium (NiCd) batteries would seem to remember what point they were charged till and eventually seems to only charge till that point. If for example, you used a camcorder for 15 minutes, then charged it, used it again for 15 minutes, again charged it etc etc etc... eventually your camcorder would crap out at the 15 minute point. It was then said that the battery had a `memory' of where it was charged till. This problem btw was actually only in the much older battery formulas. The newer technologies or formulations of today do not have this problem.

In reality, one can create the "battery memory" effect only by discharging a battery to precisely the same point, and recharging it, hundreds of times. No one ever does this with a camera.

The real problem is overcharging. When you leave a battery on a charger after it's fully charged, the charger continues to send a slow charge through it. This changes the crystal structure of the Nickelic Hydroxide (NiMH) from its beta to its gamma form. This form discharges at a lower voltage than the beta form. The result: after the beta form has fully discharged itself at six volts, the gamma form starts discharging at, say, 5.4 volts. If your camera needs a steady six volts to keep operating, this "voltage depression" will shut it down. The camera can't use the juice that's left in the battery. Engineers like to call this the "lazy effect". Let us call it that too, and leave "battery memory" to the satellites.

Also, it is important to note that NiCd is more susceptible to overcharging than NiMH. That is why NiMH batteries are said to not have a memory problem. Lithium Ion batteries are different. They like to be topped off and do not suffer from the came charging troubles. Read a spec sheet for NiMH and it warns "do not leave on charge for more than 24 hours". Read the same label from a LiIon battery and it says "do not leave on the charger for more than 7 days". A little different, eh?

What's a "no memory" battery? In some cases, it is a battery with an additional cell. It might deliver a little more than seven volts though you use it on a six volt camcorder. The extra volt does no harm, but delivers a safeguard against "laziness."

The solution: don't overcharge your batteries. Don't "cycle" your batteries (i.e. discharge them all the way) every time you charge them. Batteries that can take a fast charge don't build up the gamma crystals as readily as the "trickle" chargers and batteries. Don't store your batteries in high temperatures and don't charge them until they feel hot. Don't ever discharge a NiCd down to zero volts. This could cause "cell reversal" and even an explosion. Use a refresher that leaves about a volt per cell when discharging.

BTW.. I used to have problems with some clients that their cellphone batteries would not charge when they put them in their charger. I used to `boost' the (usually 6v) battery or `shock' it with several shory 1 or 2 second pulses from a 12v power supply. Just like the refibulator used to jump start the heart, this boost would shock the battery back to life. It can repair cell reversal and give the battery enough power to accept a charge. It would also happen if an uncharged `new' battery was left too long in stock. A quick boost and the battery worked just like new.

Hope this helps everyone 'become friends with your batteries'.
marius