Charging 18V cordless drill batteries with PV

[SUNTRONENERGY]

I am looking to charge (2) 18V drill batteries @ once while on the job site. For the most part I want it to be a direct feed situation but would like a small battery bank on the truck that will allow me to charge on rainy days etc. Has anyone done this before that could provide some guidance?

Thanks!

[Mike90250]

Each brand of battery tool, has different size cells, charge rates, and voltages. It's best to use the factory charger. You could find out what the factory charger consumes (20W, 80W, 200W) and use your vehicle battery, along with a right sized DC-AC inverter. Beware the Mod-Sine inverters, some of them will fry tool chargers in minutes. Best to use a pure sinewave inverter for anything expensive you care about. it's hard to beat the Morningstar SureSine, 300 Watt inverter, w/600w surge for 10 minutes.
To keep your vehicle battery from being depleted, you can use a panel sized about 50% larger than your charger's draw [ 90W charger - use a 150W panel ] to keep your battery topped off. Since the panel will likely be just laid on the roof or hood of your car, you will not get full output power from it.
Use a Y cigarette lighter adapter, and plug the goodies in. And hope your buddies don't steal the expensive solar panel.

Or you could build a deep cycle battery and inverter into a milk crate, and shade it with a solar panel !