"One thing I found out, don’t plug your chargers into an inverter. The waveform isn't a true sinusoidal wave and the manufactures say it will damage the batteries. I found that out after I tried to make a cheap car charger."
After reading this statement I became concerned as I have charged my Porter Cable, Dewalt and Milwaukee batteries on my service truck with a 900W inverter for the last 3 years. I posted a question on the Milwaukee Heavy-Duty web site asking if they advised against using an inverter or if it would cause poor battery performance. Their response was they test all of their chargers for use with inverters and state that if the inverter is rated 220W minimum that it wasn't any problem. They said their chargers buffer any waveform modification or distortion.