I had not driven this '02 in a few weeks and when I tried to start it the battery was dead. After charging the battery it tested out fine with a commercial battery tester even though it's 6 years and 150,000 miles old. I anticipate there will be times ahead when it will sit for weeks or more than a month at a time so short of disconnecting the battery, I was going to connect a VW solar maintainer I have directly to the battery. There is no electricity where I store the car so I can't use a plug in device. Would there be any problems using this? I have one of these on a Cadillac and it starts right up after sitting 3 or 4 months.
This is the type I'm using: eBay Motors: VW Solar Panel 12V Battery Charger OBD II boat rv car (item 330286504185 end time Nov-20-08 18:42:04 PST) I bought a half dozen a while ago for the cars I don't drive too often. They plug into the OBDII connector on VW's and suction cups mount them on a window.
I use a VDC Battery Minder on all my equipment, but of course my equipment is parked inside under lock and cover, with electricity available. My 2004 Prius battery is still going strong
That should work just fine, as the OBDII connector is always powered from the 12V battery. Personally I would be worried about plugging into the OBDII to charge a battery, but it should be fine on the Prius if it works on the VW. I'd check it though before relying on it. Connect a good quality voltmeter to the 12V boost terminal under the hood and watch to see if the voltage goes up when the sun shines. It would need to get up at 13V or more to charge the battery.
I would connect directly to the battery with alligator clips and run a wire from the trunk, outside, and in through the back door and put the charger on the front dash or window. I went through this with another car by plugging into the OBDII connector and it turned out that it kept some computer awake continuously and actually drained the battery. VW must have some program in the car's computer that keeps it asleep while this is connected.
