A good 9V battery/2XD batteries cost $5
Weak ones cost $2.

My charger isn't exactly functioning. Low current, I suspect.

But the thing is, will one good battery last longer than 3 weak ones? Got to do an experiment. Expensive one though.

Experiments to do.

One good 9V battery versus 3 cheap 9V batteries.
5 + (3X2) = $11

One good 9V battery versus 3 cheap D batteries.
5 + (3X1) = $8

(Good) 9V batteries versus D batteries.
One D battery is 1.5V. 6D batteries = 9V
5 + (6X2.50) = $20

(Bad) 9V batteries versus D batteries.
2 + (6X1) = $8


Not feasible. I'll not try the D batteries. I'll need at least six to make them functional. Too heavy. As for the 9V batteries test, I'll do some research on the net.