[quote]ORIGINAL: hobbyenthusiast

Is there an easy and/or relatively cheap way to tell how many volts are left in a battery?
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Volts do not mean much if anything for NiCad or NiMh although they are rather indicative of the amount of energy left in a Pb or LiPo. Even a nearly dead NiCad or NiMh will read a rather high voltage if there is no load on them. To answer your direct question, yes, any voltmeter (even a cheap one from any source such as Harbor Freight) will give a reasonably accurate voltage reading, it is how you interpret it that counts.
If you want some good info on batteries, check out the following:

http://www.camlight.com/techinfo/techtips.html
http://www.whenshtf.com/showthread.php?t=2153
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://www.hangtimes.com/redsbatteryclinic.html

The last one is especially good as it covers lots of info on different battery chemistries.