I got the universal charger mostly to try restoring some 18volt tool batteries that have gone south. I've just started to work with it and decided to try rejuvenating two 18volt Ryobi tool batteries that my brother had and said were now useless. I used a cordless angle grinder to discharge them with and timed how long until the grinder stopped.
Battery 1 - I charged with the universal charger and discharged with the angle grinder and it took 16 min 50 seconds to discharge for the first run. On the second run with the universal charger it ran for 16 minutes and 40 seconds. For the third run it ran for 16 minutes and 30 seconds. I then charged the battery with the universal charger until it showed charged. As the voltage was still under 19 volts I then put it on the Ryobi charger and it charged for around 20 minutes more before shutting off. I ran it down in the angle grinder and it ran for 17 minutes and 55 seconds. This was a good test as it showed the energies from the 2 different chargers were compatible with each other.
Battery 2 - I charged with the universal charger and discharged with the angle grinder and for the first run it ran for 15 minutes. For the second run it ran for 15 minutes and 30 seconds. As I was out of time I didn't do a third charge with the universal but charged it with the Ryobi charger for the entire charge. Discharge time was 17 minutes and 35 seconds.
Battery 3 is a new Ryobi battery in good condition so I used it for the control battery and only charged it with the standard Ryobi charger. For the first run it ran for a little under 14 minutes. For the second run I think the charger shut off before it was fully charged (happens sometimes with this charger) as it only discharged for 7 minutes 55 seconds. For the third run it ran a little under 14 minutes again, and for the fourth run it ran for 14 minutes and 50 seconds.
Conclusion: Both batteries 1 and 2 were useless with the conventional charger, but after only 1 charge each with the universal charger, they both exceeded the capacity of a new Ryobi battery that had only ever been charged on the conventional charger.
After having been charged with the universal charger 2 or 3 times, they would yield even greater capacity when charged with the Ryobi charger than a new battery has when charged on the Ryobi charger, as much as 4 minutes longer discharge time.
This is a great charger. It's possible I could have gotten about the same results with just one charge on the universal charger, something to look into further.
I've got about 10 Dewalt 18volt batteries, some of them pretty far gone. At $60 a pop, if I can keep them going for years, I'll have made much more than my money back just on these batteries alone. This charger is a great value and will pay for itself many times over in the years to come!
Robert
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