Only an ordinary battery desulfation pulse generator is necessary to
rejuvenate a battery. It only requires high current pulses to destroy
the sulfate crystals. The pulses have to be short to keep the mean
power low to not heat the battery. For electronics people you can
build one yourself:
http://www.flex.com/~kalepa/desulf.htm
Or you can buy one commercially:
http://www.megapulse.net/
http://www.pulsetech.com/

When measuring with an oscilloscope across the battery poles with
these circuits turned on you will see a ringing.

A good way to test a battery's condition is measuring its internal
resistance. If the battery is sulfated, so that only part of its
plates has contact to the acid, the resistance will be high even
though it is fully charged. The battery will then have a lower
capacity (Amphrs) than it was born with. So it isn't enough to
measure the specific density of the acid. A high current load test can
destroy the battery. A low current load test takes time. So try this
"Car Battery Tester":
http://www.geocities.com/CapeCanaveral/Lab/5185/circuit3.html#TESTER

Or perhaps this simple circuit:
http://www.maxim-ic.com/appnotes.cfm/appnote_number/184

Another option is to measure the no load voltage, and then the load
voltage and current, and use the measurements to calculate the
internal battery resistance. The voltage difference divided by the
load current equals the internal battery resistance.

(1) R_battery = (V_unloaded – V_loaded)/I_loaded

Some aspects of battery impedance characteristics:
http://www.telepower.com.au/INT95b.PDF

How does the internal battery resistance affect performance?:
http://www.batteryuniversity.com/partone-22.htm

To read the whole book: http://www.batteryuniversity.com

Revolutionary Battery Grading Technology based on Fast Impedance
Measurement, Analysis of Spectra, and Correlation:
http://www.kkpc.re.kr/powergraphy/QC.htm

Battery information links:
http://www.uuhome.de/william.darden/batlinks.htm

Regards
Ole Nielsen