I charge my 5 cell batteries with the Futaba wall warts all the time. Yes it takes longer but always gives a full charge. I use them with up to 2200 mah batteries with no problems, in fact this is much easier on your battery and will give you longer battery life (number of charge/discharge cycles) than you will get using peak chargers. Do read the referenced site mentioned above as Red's battery clinic gives very good advice on how to use wall warts.