So I installed a power outlet on the dash and wired it directly to the battery (fused, of course) so I can use it to plug in a battery tender. Anyway, got to the end and continuity checked sat, but when I read voltage, it read 0 (it actually reads 3+ for a second and then drops to zero). So I checked power directly at the battery terminals and got the same reading. Turn the key and all power works fine. I don't get it. How can the battery read zero when I know it's putting out 12V?