I've been suffering a parasitic drain problem on my S for a while now (a year or more). I originally thought I was having a battery problem (car wouldn't want to start really well, VERY sluggish like very low CCA) so I replaced it and all was good (I also replaced the alternator and starter all in the same month). Everything seemed gravy.

With the new Honda OEM battery replacement a few months ago (maybe 9 months ago) I haven't had any starting issues while using it as a DD in the spring and summer. But when I put the car into semi-winter storage I would drive it about once a week for 20-30 minutes. The car would be a little more sluggish on cranking over, but would start up no problem and would drive great. I figured it was just normal to be a little low on CCA after about a week - and again there weren't any real problems.

Well we had snow the past 2 weeks so obviously I didn't want to subject the S to that if I didn't have to. But after a window of dry conditions (right before another snow) come up I jumped in the car for a drive and when I put the key in I got nothing. No lights, no clicks, absolute zero. I took the battery to O'reilys and had them charge and test the battery. Battery was obviously dead, but he said it tested perfectly fine. I put it back in the car and went for my 30 minute drive and absolutely no problems. So I put it back in the garage, disconnected the battery and went to google.

I googled and figured "okay that makes sense, I DO have a parasitic drain then." So I ran to the store and picked up a new digital multimeter today (a week ago) and when I went to take a reading, I got a reading of 0.05 on the 10 amp setting that correlates to 500 mA. And if I lifted the lead off and put it back on it would start at 0.25 reading and then jump quickly down to 0.05 or 0.06 reading (still on 10A setting). That would be a HUGE drain... wouldn't you think? The car was bone cold and had been off in storage with the battery disconnected for a week. So there was no computer mode or anything to worry about (if our cars even have that). If I had a 500 mA drain, I would think I would have much worse drain problems?

Anyone got any advice on this? Maybe I'm doing something wrong?

Thanks in advance!

 

bump could really use some help on this guys. Google hasn't helped me because a 500 mA reading is very high

 

0.05 reading equals 50mA. Not 500mA. Did you pull fuses one-by-one to find the biggest draw? Seems that something must be still "on" when you turn the car off. You have an aftermarket alarm or stereo setup? Maybe, try pulling the fuses associated when those devices to check to see if they are drawing current, when ignition is off.

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I don't understand. If the setting is on 10A and I'm reading 0.05 it would be 0.05 x 10 = 0.5A. 0.5A x 1000 = 500 mA?
Either way, a 50 mA is borderline "high" which would be consistent with draining my battery over 2 weeks?

I didn't start pulling fuses because I didn't know if I was getting a wrong initial reading. I will probably start pulling them tonight and see if I see a change.

 

No. The range you are setting is 0 to 10 amps. The readings (digital, right?) are absolute, not relative (no need to multiply readings by any factor).

50mA draw, with nothing on, may still be a problem over time. Anyhow, here's the link to one of the better YT DIY's.

https://www.youtube.com/watch?v=KF1gijj03_0



http://www.youtube.com/watch?v=KF1gijj03_0

 

Tracking the same issue on my TL. I have an aftermarket amp and subwoofer in the trunk, but I also run my HID backup lights off the same power line. I was able to ascertain the draw is on that power line to the trunk. Its been too cold to troubleshoot any further, so I just disconnected the line at the battery for now.

The point of my story is to try to narrow down the draw starting with the largest solutions first. In my case, it turned out to be the main power line to the trunk. I suspect that when I get into it even further it will either be my amp and/or fuse or distribution block.

If you don't have a power line going to your trunk, you'll have to figure out where the drain is by using a more logical approach. What was the last thing you worked on before the drain appeared? Sounds like we are talking about an extended period of time, so that may be more difficult than you would think. Usually, these things turn into a "smack my forehead---I should've thought of that first"-type thing.

Good luck.

 

This is always going to be an aftermarket system causing the parasitic draw, alarm or stereo system. Let us know if either have been added to your car. Pulling fuses is an easy first step to tracking it down. Good luck.

 

I have no aftermarket electrical components on the car. I will try pulling fuses tonight.

 

No possibility of some light staying on, after you pull the keys? Maybe, the trunk light?


Good luck with the hunt!

 

I forgot to mention, I tried that one a while ago. I put my phone with the camera on in the trunk and closed the lid. Turned out that wasn't it.

I just got done pulling every fuse except for the 100A and 40A that have to be screwed down (I was lazy).
Every fuse I pulled showed almost zero fluctuation (then again, I was on a 10A meter so the original reading was 0.05) except for one... drum roll please.... the 15A "alternator" fuse.

So weirdly enough, I replaced my alternator about a year ago. It looks like it may be a failed diode pack that is allowing current through? Can anyone confirm this. I've replaced the alternator twice on this car already (original was flickering the light... the second one I messed up myself by shorting it out... so this is the 3rd one) It was installed correctly (Jordan actually installed it since we had the head off the car anyways) so what gives?

I will note, that this was an Advance Auto alternator, but it was a refurb'd DENSO.

If I take it off the car and take it to Advance Auto is anyone pretty sure it will fail on their machine that tests them? If so, I'm sure I could get a replacement one from them since I have the original paperwork from having bought it from them.