I have a 5 watt 12 volt that I bought on eBay. Actually it's a replacement. The first one stopped working after less than 1/2 hour of use. The seller replaced it free, but said they were sensitive to low voltage, noise on the power line, bad connections, etc. I think he was just making excuses, but I don't really trust the replacement much. The original had never been mistreated in any of these ways. I had just rigged up a light socket rubber-banded to the top of a SLA, and was only beginning to decide how I was going to use it. I had crimped push-on connectors for the SLA, wires under tight screws on the light socket and everything instead of the alligator clips I had been using. That's when it blew.
I've got the replacement in a ceiling-mouted 12 volt socket, and used it less than 5 minutes. Mine was actually consuming more like 7 watts by my ammeter, but I figured the 5 watts was what the bulb takes, not counting the efficiency of the inverter built into the base.
The one I've got is probably cheap junk, but I wouldn't consider them very durable.
Nice finding with the DynoHub, but the CFL probably prefers cleaner, more constant power.
Alan
