Black Box Charger Comparison
To test the efficacy of the Black Box Charger, a battery discharge device was constructed.
This device takes a fully charged battery and, using a speed controller, runs the battery down through a set of resistors.
It records the time it takes for each battery to reach cutoff voltage (see picture below).
For the test, 10 different battery packs were first charged on a 15 minute timer (crank) charger then discharged.
Next, they were charged on a Brain peak charger and again discharged.
Finally, they were charged on the Black Box charger and discharged.
These tests demonstrated that the Black Box charger gives up to a 350% (avg? +- standard deviation) increase in run-time over a standard 15 minute crank charger, which are highly inefficient for properly charging a battery pack.
The Black Box charger gave up to a 130% (avg? +- standard deviation) increase in run-time compared to a Brain peak charger.
Note: This Brain charger cooked the battery it was charging when the battery was left on the charger for several hours.
However, it is perfectly safe to leave a battery on a Dewalt charger indefinitely.
In fact, it is recommended that you leave a battery on a Dewalt charger so that the charger can apply its Tune Up ModeŽ to equalize the battery and then keep the battery fully charged with a trickle charge so that it is ready to go whenever needed: a battery left outside the charger discharges at a rate of about 2% - 5% a day
So for all of the stated reasons, I have found that a modified Dewalt charger is the most reliable, safest, and simplest charger for 7.2-volt NiCd hobby batteries.
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