>Alkaline batteries ARE rechargeable. I've had the same set in my >remote controls for many years. Do a web search for alkaline chargers >and you'll find plenty. I was told at the time I first found out about them >that there was a "conspiracy" to not tell consumers that alkalines are >rechargeable, to make them buy replacements. As far as I can tell it's >still not common knowledge, as NiCd are promoted as being THE >most common rechargeable. I cannot discount the fact that there could >be a "conspiracy", although I'd prefer to look on it as "not telling the >whole truth for the good of the company". Same thing with long-life >car tyres, light bulbs, clothes, etc etc Well, yes and no. To some extent it's true and it will certainly be worth trying but, for reasons noted below, I believe the results will vary significantly with application and battery treatment. Modern "Rechargeable Alkalines" (RA) are also sort of rechargeable and they have taken the known rechargeable capabilities of Standard Alkalines (SA)and optimised them. Consequently you can expect that an optimised (ie standard Alkaline) will be worse again than one which is optimised for this purpose. Lest you think there is nothing to the optimisation, note that the major patent holders are Canadian and Rayovac build rechargeable alkalines under licence to them. Let me tell you a little about RAs, I consider it reasonable to assume that SAs will be no better and quite possibly somewhat worse in many areas. B, IMBW :-) I have looked into RAs as a current client insisted on using them in a product that I am doing part of the electronics for. They are not nice devices compared to NiCd or NiMH when it comes to rechargeability. They do have some advantages though including - - High relative initial terminal voltage (over 1.5v/cell) - High relative shelf life -potentially years. NiCd is months and NiMH is best measured in weeks RA's will weep nice caustic goo if you charge them heavily. "Heavily" is not well defined in the extensive Rayovac data sheet / application note. "For further study" :-) RAs do not like to be floated up indefinitely - they will accept extra voltage if you provide it and die. They need to be limited to a maximum 1.6 - 1.65v per cell (depending whose data sheet you read). RAs are best used at low discharge currents and very importantly at low depths of discharge before recharging. Paradoxically, if you MUST deep discharge an RA it is much better done at a high discharge rate. The gross anp-hours provided at high rates of discharge will be much lower than at low rates of current BUT the battery will recover better and its lifetime will be much less harmed. If you trickle an RA down to under 1v per cell you may get as few as 10 discharge cycles. if you crash it down at high current you will get many more cycles of l;ife. RAs amp-hour capacity starts off relatively high but dies rapidly. The slower the discharge rate to any given voltage endpoint the worse the degradation of capacity. RAs with an apparently healthy open circuit terminal voltage will drop their voltage severely under load. eg a battery pack of 6 x AA RAs may have nearly 9 volts open circuit voltage but drop to 7 volts odd on a 500 mA load!!! I'd say the ideal application would be something like a transmitter that sends data occasionally and charged by a voltage limited solar trickle charger. So - Where does that leave us with recharging SA's I would guess, and this is a guess, that applications such as the TV remote control with a relatively frequent current limited top up to a controlled terminal voltage would be an excellent way to encourage their long life. Use them in eg a radio and run them flat every time before recharging and I'd guess they would fail rapidly. regards, Russell McMahon -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.