Battery discharge rates for typical Alkaline and Lithium batteries - Page 1
Forum section: electronics / beginners

author: cardinals
author_rank: Newbie
timestamp: March 11, 2017, 11:14:40 pm
content: Newbie here, so sorry if this topic has been already addressed in the forums and I have missed it. I did several searches and couldn’t turn anything up. If I missed it, please point me to the right thread and I’ll gladly go there.I have come across a few forums on flashlights where folks claiming EE knowledge claim that any charge put through a typical AA lithium or alkaline battery will accelerate the battery’s discharge rate. They describe the decline as different than the self-discharge rate of unused batteries and ‘circuit drain’ caused by some devices.The claim made on the forums would seem to agree with many people’s perceived experience: the big battery companies claim their batteries will last 10 years in the package on a shelf, but those same batteries sitting in an unused flashlight seem to be dead within a year or two. (Of course circuit drain could be the culprit there).My question is, does anyone know if a battery’s self-discharge curve steepens after a battery is used even once? If so, does the simple act of ‘testing’ new batteries placed in a flashlight doom them to an early demise (like 2-3 yrs vs. 10?)I figure I can test the claim by taking 2 fresh batteries, ‘testing’ one for a moment in a device, removing it, and then waiting ~6 mos and measuring the remaining capacity in both batteries, but I was hoping to find something more reliable than my own test. Also perhaps an explanation of what causes the accelerated decline, if it is in fact, real.Thanks for any insights!

author: saturation
author_rank: Super Contributor
timestamp: March 12, 2017, 01:40:13 am
content: Hi Welcome, and no it doesn't, the self discharge rate nor the stored power aren't accelerated from its spec sheet by using the battery briefly assuming the battery has no flaws in its construction, regardless of its chemistry. Remaining power is unchanged so long as the electrodes are fully disconnected. It seems to last less in some devices because of parasitic drains caused by a soft switch or a poor mechanical switch.A battery is a chemical reaction that only proceeds if the pos and neg terminals are connected to allow the electrons to flow. Internal drain happens through imperfect insulators between the electrodes thus limiting it calendar life. The alkaline electrolyte can corrode terminal seals slowly, or gas generated by reaction from imperfect insulation is not vented gracefully can leak the seals reducing the shelf life of a battery, virgin or used, independent of internal drain.I currently have 2 working alkaline batteries running since late 1970s in my Casio FX calculator, the original set it came with. Clearly batteries can be designed well, if it is still working by 2020 it will be over 40 years old.https://www.eevblog.com/forum/chat/fluke-87v-and-9v-energizer-lithium/msg172228/#msg172228Quote from: cardinals on March 11, 2017, 11:14:40 pm

author: cardinals
author_rank: Newbie
timestamp: March 12, 2017, 06:30:22 pm
content: Thanks for the insight, Saturation!Yes, I think for the phenomenon described in the other forums to be real, it would require the insulators between the terminals to somehow be damaged/altered by a load being placed on the battery. I suppose battery technology would have addressed an issue like that by now if it had dramatic affects on battery life.My guess is that what the folks in the other forums are experiencing is 'circuit' or 'parasitic' drain but aren't completely aware of it (which would make sense as it varies from flashlight to flashlight.Thanks again!