Our car seems to be running fine now but I’m trying to make sense of an electrical anomaly that shut down most of the car’s systems for a few minutes last night.
History: after 3-4 days of non-use we found our 2008 LL Bean Outback’s battery completely flat for the first time, ~ 100mv. (26mo. old Interstate battery, no heavy drains, no cold winters, charging system is healthy). The only item obviously amiss was the rear hatch being in the half-latch position which activates a door open warning light at the dash, but the rear dome light doesn’t come on unless the hatch is actively lifted against the half-latch and which did not appear to have occurred, though it’s plausible…
After recharging fully followed by sitting awhile the battery measured ~ 13.4vt. open circuit (it was isolated while charging to avoid fighting a potential drain). The negative terminal was reconnected and as the key was advanced the dash panel illuminated, bells chimed, and all seemed normal. Immediately upon turning to the starter position the electrical system went dead, no solenoid click, all dash lights off, door locks didn’t work, seemingly nothing. I took the key out and tried again, nothing. I did find the reading light over the windshield would turn on with its switch, but not the headlights, dash lights, nor cigar lighter socket (which comes on only with the key). The battery still measured > 13V and connections were tight. I was beginning to think about master links but tried the key once more and all came on and the car cranked and started normally. It held charge overnight and started properly again this morning. Previously the car has started normally after disconnecting the battery for a day or more while performing mechanical work.
Parasitic drain was measured after the battery was charged and before reconnecting the negative terminal. Initially ~ 500ma, it gradually dropped over about a half minute to ~ 125ma. While drainage seems somewhat higher than desired (and probably includes the hatch open warning light) it isn’t sufficient to drain a healthy battery over just a few days. Has anyone else experienced this or have an explanation?