Question......I am using a DC to AC power inverter in my truck, to charge my Ridgid 18v LI batteries with on the charger. I have 4 batteries that are maybe 4 months old that are defective. The inverter is maybe 200w. I am using the 18v LI Autoshift drill and the one handed LI saw. I use the hell out of the drill....drilling big holes and etc. Does this seem like a problem from the inverter, or could it be something else.