i used a 10 amp battery charger.on a door it seemed sloooooow to me but got the job done pretty good. i 've got a 35/100 amp charger with a three year warranty to try on some rear barn doors that some nut (p.o.) blasted clean amd left out in the rain for a year or so. i hope thie don't go the tim allen way with too much "horse power".tech tips has the formula for the mix of powder to gallon of water. tom
