questions about batteries

I have a pile of aa batteries that are mostly dead but some are good. I was wondering what the best way to check them would be so i can divide them up according to how much juice they have left. I plan on using the almost dead batteries with my led lights. do standard batteries gradually drop off in voltage? I heard nimh batteries stay fairly constant until there almost dead.

Hello!

I use a Radio Shack digital voltmeter to sort out old batteries. I have made a list by trial and error of the approximate usable ranges in voltage for regular alkalines, 123a lithiums, and the B65 rechargable Sure Fire battery for the 6P. Keep in mind that the list I made was for running incandescent lamps for a minimum of 50% of the usual runtime. LEDs will work down to lower limits.

alkaline: 1.35v (1.52v when new)
123 lithium: 2.8v (3.1v when new)
B65 NiCad: 4.8v (5.3v freshly charged)

My impression is that the primary batteries discharge at a linear rate. I'm not sure about the NiCads. I'm fiddling around with
NiMH aa's now.

Good Luck!

Hi!

I think the best way to test them is to check the current capability (like the duracell power check does). Just hook a 1.5 Ohms resistor on the tips of your voltmeter and the battery then in parallel. You will son recognize strong differences in voltage breakdown between good and bad cells...


Bye!

nicd/nimh have a very flat discharge curve.
starts at 1.4v quickly settles at 1.2 or so and nearly flat till a sharp drop at end of cycle.

Phantomas:

I don't understand your suggestion with the resistor. Are you suggesting to place a resistor on each lead? Is the purpose of the resistor the same as placing a "load" on the battery?

I have noticed that after registering the same voltage on several batteries (say 1.45), I then place them in a light. The light is initially bright but then after a short time, almost dies. Rechecking the batteries always reveals that one of them is almost dead (< 1 volt) while the others are OK. If I could easily place a load on the battery while checking the voltage, I could determine the true amount of usable life left in the cell. Right? Anybody have any ideas on what I could do?

Thanks.

Why not just use a battery tester (with a resistive load) built right into it? 1ma,10ma,150ma etc...
-Like R.Shk.#22-090 -$15.

I was just looking through the radio shack flyer. they have that battery tester on sale for 10. im gonna go pick one up tommorow.