I had two of the twin pulse chargers. I thought they were fine minus the regular false peaks, cooling fan stopping/noisey and no adjustable settings.

Then I borrowed my buddy's IB 3800's 7-cell (same as mine) during a bashing session, he broke a major component on his maxx, therefore the batteries had already seen some run-time. My maxx took off like a bat-out-of-hell! He uses a MRC 977. I went home that night and sold both the Duratrax chargers and ordered the 977. I have never looked back.

Save yourself the headache and buy a 977 or equivalent quality charger; i.e. one that you can set the delta peak AND is a linear charger, not pulse like the Duratrax. You won't believe the difference until you try it but believe me, there is a huge difference in battery performance.