On 13 March 2015 at 14:34, Justin Richards wrote: > Batteries, particularly Duracell are not cheap. > I have several 6V Duracell batteries in storage that I use rarely and was > just curious if their shelf life could be improved with a very light floa= t > charge to help combat the self discharge. > A quick search seems to offer keeping in them in the fridge as one method= .. > On face value this appears to a valid offering. > Perhaps an experiment is in order ... measure the current surface voltage > and and set an adjustable voltage supply at that value and connect. > It's my understanding that all "Alkaline" primary cells are "somewhat rechargeable". I looked into this to some extent about 15 years ago when a client was using "rechargeable Alkaline" batteries that were specifically intended to be recharged over a finite number of cycles. He had less good results wity these than he'd hoped and I was only peripherally involved - I designed a charging circuit to the desired specification that was used but did not get involved in long term testing or user experiences - equipment was made in Taiwan and sold elsewhere than here. The batteries involved had specific related patents but my (possibly faulty) recollection is that Rayovac had been involved to some extent in wider Alkaline charging. It was all the rage in the amateur community 'back then' - possibly due to the relatively higher cost of "proper" secondary cells. So, all that said, I'd expect that a low level of "charge" could well be useful. Given that "best before" dates on top brand [tm] Alkaline AA cells are now of the order of 5 to 7 years (which I'd tend not to trust), shelf life may well be improved by an exceedingly modest charge. If you assume an AA Alkaline has 3000 mAh capacity at low discharge rates then the one year discharge rate is 3000/8765 or about 1/3 mA and the 5 year rate is 3000/8765/5 =3D~ 70 uA. So a 100 uA charge rate MAY be useful and a 500 uA rate would be expected to be more than is needed but "not too likely" to cause catastrophic self dismemberment or odious exudations (as adumbrated re by Bob B). But, I may be wrong. _______________________ I've heard refrigeration mentioned on various occasions but have not tried it. Sounds sensible. Freezing is 'to be avoided' Even a nicely cool rather than warmer than needs be storage location should help. Returning to ambient temperature before use is desirable. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .