How do many of us deal with electrical issues? Ignore them.
Our E46-chassis BMW M3 had been shedding some electrons–not enough to leave us stranded, but we knew there was an issue.
In fact, we knew it was a problem when we bought the car because the seller–and old friend–told us. But, he added, it wasn't bad enough for the …
Came for the project car update, stayed for the Metallica.
In reply to Colin Wood :
Thanks. Always try to over-deliver.
Timely for me, nice!
bluej (Forum Supporter) said:Timely for me, nice!
Thanks. It's basically the article that I wish I could have found. So I wrote it.
This process will work for any car. Have a drain? Here's how to (hopefully) track it down.
Bonus Metallica, too.
New cars can take about an hour before they go into "sleep" mode so wait a bit to obtain a solid result.
I had an 84 Mustang 2.3L that was draining the battery on a regular basis. I put my meter in line with the positive cable and could see that there was a couple amp draw even when the car was off. I noticed that every time I made the connection from the battery to the positive cable that I could hear a click under the dash. I made a remote switch out of a length of speaker wire and climbed under the dash. I kept making and breaking the connection until I finally felt a relay click with my fingers. I called the dealer and found out it was for the ignition system. That was the first time I had ever heard of something failing "on" instead of "off".
I agree this is the article you need when you have a draw. Just finished playing this drain game with my Cr-v and behold I had mis-wired my new driving light relay to be energized off and de-energized on. (swapped the 87 and 87a pin locations in my pre-wired relay connector.) The coil of the relay was enough of a draw to bring down my old battery over 5-7 days. I also lost a cell in the battery along the way, so new battery and now I have an acceptable 500mA draw but wish it were closer to 200mA. My main draw now is the radio/acc circuit, which is to be expected.
My hope was to get through this without having to replace the battery, hence the womp, womp when it died. Both Carl and James said the same thing: Get the battery tested, but don't be surprised if you need to replace it. So at least I went in prepared for the worst. But, hey, we all got an article out of it.
Great! But can you leave the car un-attended for several days without a battery maintainer to keep the battery charged?
And I cannot believe that no one has replied "I wondered where I left that wrench".
Scott (Who needs to go back outside and finish putting an axle in his Jetta)
The new battery just went into the car, but after Amelia I'll chart the battery over a week or so.
Good enough.
And the axle is done.
Scott
Considering the drain has greatly been minimized, I have good hopes.
Any drain news?
GCrites80s said:Any drain news?
Sadly, no, no news on the drain. I haven't had a chance to let the car sit for a week or two. (I need to move the car in order to get out the lawnmower or get up into the attic.)
Another reason I'm curious is that I have a 0.01v per day drain (as of day 4) but the battery is 6 years old. I did the little load test that multimeters come with but I don't know if that strains a car battery enough. It tested good (green). I need to get around to doing the amperage draw test but I have 2 other projects going on.
I had a few friends who know more than me suggest the test at the parts store. So that's what I did, and their tester said that we needed a new battery. It was a few years old.
Yeah I'm used to seeing the store lights dim when they test batteries and alternators at the FLAPS 
I got a new battery, which I needed. The old one was even older than I expected at 2014. After that:
Here's a 6-day breakdown
12.85
12.63
12.51 (I got in and out of the car a few times after the previous reading)
12.55 (notice it went UP)
12.54
12.52
Still lighting up the test light. So I gave it the amp draw test... 0.01 mA. Sometimes 0.00. Is something intermittent happening while the car sits? With the stock fuel pump the pump used to cycle every once in a while for a few seconds as the car sat. It was fairly loud when it did it too. Fuel pump went bad and was replaced with a Walbro 8 years ago. I have never heard it cycle since even with spending hours in the garage. Now the horn button is a little sketchy and corroded which makes the horn only buzz weakly when you hit it. I am swapping steering wheels hopefully this weekend so that sketchy connection will be out of the loop.
Anyway, is the battery draining by .01-.02v a day when it's 90+ degrees out really that big of a deal? It may not be.
12.50 today after skipping a day.
Note that this radio's memory only keeps track of clock time and what song you were on. All the rest of the memory functions are burned to flash memory which is demonstrated by the fact that the car sat for 2 weeks with the fusible link blown and one week with the battery disconnected. All other settings were not forgotten such as tone shaping, Bluetooth syncing, balance/fader, speaker size and levels. I'd Imagine a lot of head units made in the past 5-10 years also use flash memory and aren't real drains.
After nearly a year, what did I find out about my crazy-weird drain? It was the power hatch pull down! Most cars don't have these. What happened is that the motor/gear housing was cracked so the motor was turning on intermittently trying to bring the hatch all the way down but couldn't do it because of the cracked housing. And it was really quiet since it was only trying to turn but really couldn't. But it was still sucking down the amps. It was so unpredictable because it wouldn't try for days sometimes. When I would drive the car the vibration, bouncing and flex would make it try to pull down but since it wasn't that big of a draw the alternator easily made up for it.
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