Hi Mike: I've done quite a bit of battery load testing over the last couple of years using a laptop and electronic load. For some of the latest results using mostly rechargeable Ni-MH AA cells, but also some primary AA cells see: http://www.pacificsites.com/~brooke/5590BA.shtml#RTTbl In the table the battery capacity is expressed as run time under a defined load which is typically some radio receive current for 9 minutes then the transmit current for 1 minute, with the cycle repeated until the voltage drops below some threshold. The associated plots give you a good idea of the battery internal resistance. Note that the results depend heavily on the quality of the AA battery holders. The tests on the above page were done using custom AA holders made with very much lower resistance than stock battery holders, see the current capability table to get a feel for that: http://www.pacificsites.com/~brooke/5590BA.shtml#CC I have extras of these holders for sale if you need some. The test results for rechargeable batteries vary depending on how the cells were charged, how long they have been sitting, etc. Have Fun, Brooke Clarke, N6GCE -- w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com Date: Wed, 10 Aug 2005 14:38:22 -0500 From: Mike Hord To: "Microcontroller discussion list - Public." Subject: [EE] Battery life testing Message-ID: <88eca9220508101238328f546d@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: list Reply-To: "Microcontroller discussion list - Public." Message: 9 I've been kicking around the idea of doing some battery life testing for awhile now, since I can never seem to find the information I REALLY want. What I'd like to do is set up a test rig which allows me to constant-current load a battery at, say, 100 uA, 1 mA, 10 mA, 100 mA, and just maybe, 1 A, and then log the voltage on the battery for later analysis. In the end, I'd like to have a moderate sample size (say, four to eight cells of AAA through D cell, of each of the top few manufacturers, plus the same quantity of 9V batteries, at each discharge rate). Lots of batteries, of course, but I really would like to have some hard data that I could use to give good estimates of runtime for batteries. Making the test rig, etc, is easy enough, but I'd like to then make this info available online, but I don't know if that'd open me up to legal action on the part of a battery manufacturer who's displeased with my findings. Or, if anyone knows of a site with hard data (NOT nebulous graphs made under poorly defined circumstances, which is what I always seem to find), I'm all ears! Mike H. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist