Electrical Issues? - Honda Civic

I drive a 2005 Honda Civic. Earlier this year (January or so) it started randomly completely dying either in traffic or right after I parked and shut the car off. The sequence of events are any mixture of the following:
-Heater/Airconditioner noticeably looses power then shuts off.
-Blinker will speed up then eventually shut off.
-Headlights will dim significantly then shut off.
-Radio/Clock completely shuts off.
-Wiper blades shut off.

At this point it I can normally make it to my destination or pull over (if I’m lucky), but once I turn the car off I can’t turn it back on. Occasionally, It’ll die in traffic, but before this happens I’ll notice a significant decrease in the ability to accelerate. If I try to turn the car back on, generally, the dials will sputter/shake, the dashboard lights will light up, and sometimes the the radio will work, but I can’t start the engine and sometimes it’s just dead. At this point I can wait anywhere from half an hour to several hours and it’ll generally restart, but will suffer the same issues. I can give it a lengthy jump and it’s generally good for another 200-400 miles or so.

It stopped doing this as the weather warmed up so I either figured it was somehow tied to my heater, colder weather, or it just fixed itself. Well, today it did it again (first time in probably 8-10 months). I haven’t been able to jump it yet to see what that might do, but I left it in the parking lot for about 45 minutes after it died and it started up when I returned. I was able to make it home before it died again and now it sits, in my garage, dead (save for sputtering dials, etc. when I try to start it up).

I have become quite familiar with the mechanic over this issue and he’s not been able to figure out the issue; mostly because when it’s jumped it runs fine and you can’t tell anything is wrong. We’ve ruled out the alternator and battery. I’m at a loss and beyond frustrated. Any help is appreciated.

I’m not sure how the battery / alternator were ruled out but from time to time someone comes through with issues that look like power issues, report the battery & alternator have been checked, and then later find out it was the battery/alternator anyway.

I think that you’re going to find that either the battery or alternator or both are having intermittent issues. And/or I think you’re going to find that your main power cables have a bunch of corrosion hidden under the insulation.

If you want better suggestions than that then you need to provide people with some fairly detailed info about what your mechanic has done. Otherwise we all play this game where it takes three days to get past the “oh, that’s already been done…” comments.

I don’t know what kind of “mechanic” this is but you do tend to get relatively poor attention from dealerships and national chain auto “care” places. If I was your mechanic I would ask to drive the car home with me one night while it was hooked up to scantool to record live data of what the car is doing while its being driven.