My digital VOM probably draws very little current when measuring voltage, so if I am correct, when testing battery voltage it would be correct to measure while under a normal load. OK, but what load for an AA alkaline battery? What about a lithium battery? My digital camera seems to draw nearly 1.0 amp, and makes short work of batteries. Thanks, Dave
Radio shack has a battery tester that draws some load. A switch select the battery type. All I can say is that it's better than a VOM.
alkline batteries do have the tendency to drop their voltage as they get used up. Depending upon the load, they'll drop even more but that really isn't necessary. A fresh battery should be on the order of 1.7V with an end of life usually being about 1.2V or less.
-- Why do penguins walk so far to get to their nesting grounds?
Go to the battery maker's website and look for technical data on the battery in question. The datasheet will tell you what the test load (ohms) and expected (required minimum) voltage will be.
Joe Gwinn
My old Radio Shack battery tester tests at 150ma load except for button cells which are tested at 1ma.
Don Young
For yet another take on this, I'd say you need to test with the load presented by the equipment the batteries are powering. For, say, the wireless keyboard I'm typing this on, voltage at essentially no load is the key factor. It draws so little current that a test under load would have me throwing away batteries that would still work for weeks. For a digicam, especially if you're using the flash, you definitely want to test under a heavy load. To be precise, you'd create a test load that matches the peak load of the camera. Then you'd need to determine the minimum voltage the camera is happy with.
Personally I just put my meter in 10 amps mode and touch the battery terminals for about a second. This lets you see both the initial current, and how quickly it drops under the exceptional load. To "calibrate" this test, just try a few sets of batteries that no longer operate the camera properly.
Loren
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