I've been a "shade tree mechanic" since the mid-70's and I think I'm pretty good at diagnosing issues. But this one is a real puzzler....

2007 Accord V6 we got in 2008; now has 86,000 miles on it. Not a lick of trouble, until recently:

Before we go too far, I'm in Texas and temps last week were in the hundreds. I've never lived in sub-zero weather.

Used to be the Accord would start immediately: Turn the key to start and it turns over maybe twice and then it's running; so fast that we could often just "blip" the key without really even holding it in the start position. But now, when we turn the key, it turns over about 4 times at about half the usual speed, then the speed doubles and it turns over 5 or 6 more times before it fires up; about 4 or 5 seconds of cranking. This is how I would imagine it acting in say a Montana winter.

So, here's what happened leading up this and what I've done:
Monday last week I left my hazards on for a couple hours (forgot to turn them off when I arrived at the VFD station for a call). When I tried to start to go home, it just clicked really fast (relay just buzzing I guess). One of the other guys jumpstarted me and I drove home. Next day, the wife was going to go to town and turned the key and it did not start immediately so she took the truck. I went out, and tried to start it and it behaved to me as if the battery was dying: turns over slow, but eventually fired up (as described above). While running I checked the voltage at the battery and was getting 14.25 volts - Good, alternator OK. I killed the engine and read voltage at the battery. It was 12-something and was dropping about one-tenth of a volt per second... Ah ha! Dead battery. I called autozone in town and lined up for the wife to bring home a Duralast Gold 35-DLG just like the one we put in it in Nov 2010. (660 cranking amps). She brought it home and I installed it. Car fired right up. We didnt do much Wednesday, wife went to town Thursday, all was well. Saturday I was going to return the old battery for core deposit; went to start up the Accord and it took more effort than usual, and was just exactly as I described above. Turned over several times at half-normal speed, then several more times at normal speed and finally fired up. Hmmm, odd. Took the old battery to autozone, left it for them to charge and test, and they declared it bad, so I got warranty refund on it. They took their tester out to the car and suggested perhaps the starter was drawing too much. That sounded plausible, so I bought a starter and installed it. No improvement. Sunday, we had to go to the city for a bunch of reasons. Before we left, I checked the voltage on the battery, and before the first start it was 10.5 volts. I started it (and again acted all slow, but fired), and observed 14.25 volts when running. Killed the engine and watched the voltage slowly drop from 12.8 down to 10.54 in about 3 minutes, and hold there. We chanced it in the Accord yesterday: 250 miles, 8 hours, at least 5 starts. Every start was like I described, but no other issues. Ran great once started, everything works, wipers, radio, air. No OBD codes.

This AM, I had my wife start it while I watched voltages on my meter: 10.4v, insert key turn to ON and it went down to 10v. Turn key to start and it bounced between 9.2v and 7.8v until it fired up at which point it went to 14.24v.

So, what's that tell us? What could be wrong? I'm stumped!

 

People have reported a sticking A/C Compressor Clutch relay or A/C Condenser Fan relay as the cause of a parasitic draw which drained their battery quickly.

Located in the under hood fuse/relay box. #2 relay is the A/C Compressor Clutch relay and # 15 is the A/C Condenser Fan relay (see pic.).

 

Thanks for the suggestion
Pulled every relay in that box, started it up, saw 14.3v, let it run a minute or two and killed it. No Joy. Watched volts drop from 12.3 to 11.5 over 3minutes, then for the next minute drop to 10.5v and hold there.

BTW, I think you meant to hightlight #1 instead of #2... symbology on the lid makes me think that, but I'm no expert in trans-Pacific hieroglyphics, so maybe I'm wrong.

 

Ericthecarguy has a video on Youtube about how to check for parasitic draw. I would check that out. Sounds like something is drawing power, even when the key is off.

 

The relay numbers and descriptions are what is shown in Honda manuals.

 

Thank goodness for english translations!

 

Thanks for the post about EricTheCarGuy.
I found his video and watched it late last nite.

This is my wife's car, and she drove it to town today. I asked her a bit ago how it behaved. She said "Same, except you know how it stays on the radio station you had it on last? Well I've noticed that when you start it, it always switches over to the "CDC" mode"....

DING DING DING - There's a wonderful clue!!!

When we first got it, I installed an aftermarket doohicky so she could plug ipods/iphones into it as the "CD Changer". Worked great all that time. Inspired by that video, I pulled the radio fuze, started the car, watched it hit 14.36v, then turned it off. So far, after 15 minutes it has only dropped to 12.4v! (It had been dropping to 10.5v and leveling out there after only a few minutes). We'll see if it is still in the 12s tomorrow AM before I take it to the local mechanic I'd chatted with yesterday.

Maybe the jumpstart or trying to start with dead battery zapped something in the radio circuit. I'll probably pull the CDC/ipod adapter and see if that is where the fault is.

 

No joy. 10.3v this AM, sluggish starts. It's at the local shop now.