There are some things that Visor users should never leave home without: a backup module, and if they have a rechargable Visor, a power adaptor too.
The BattPlug is a battery adaptor which allows you to use 4 AA batteries to charge the Visor Prism, Pro, and edge. It is very similar to Tech Lab's Emergency Charger which won a 2001 VisorCentral Award. It is a small 5 ounce package, which connects to the Hotsync port of the Visor with a 3.5 inch long cord.
If you want a lighter and presumably smaller charger (note that I did not review this) an AAA version is available.
One of the things about chargers is that they are so simple to use that they are idiot proof. All you have to do is plug it into your Visor, and turn the adaptor on. The plug is very secure and is spring-loaded for easy removal - just squeeze the sides.
Unluckily changing the batteries is a tad bit harder, you have to unscrew the box, and than you can slide the cover off. For our benefit though, the screwdriver on the Visor's stylus works quite nicely for this.
Rick Melton of Visorsolutions told me that each battery set should last 5-10 charges. They did that for me, and they also worked fine to use the Visor while charging it.
Say you are on the road with your Visor and your Visor runs out of juice; you can just plug in the BattPlug, use any standard AA batteries found at gas stations and charge up!