On line I purchased a new battery for my old Coleman Powermate drill. Although the new battery is Coleman it does not quite fit my charger. I used jumper wires to connect the two and found that the green light came on OK but not the red light (two lights on the charger) and after seven hours - no charge.

So I filed down the ridges on the new battery case. It plugged OK into the old charger and magically the red light came on and I was able to charge the new battery.

Question - what is different; why did the jumper wires not work; why no red light? What made the red light come on when I inserted the new battery.

Not a question of pith and moment but interesting to me.

Thanks.