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Electrical drain troubleshooting - 99 Kombi Posted by Larry West [Email] (#1140) [Profile/Gallery] (more from Larry West) on Sun, 9 Feb 2014 06:18:59 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Back in a previous thread (see link), I asked for suggestions on what might be causing my seemingly massive electrical drain over a short period in my 1999 LPT auto wagon. The last time was draining a brand new battery in 42 hours to the point where I got nothing in the cabin. No lights, no central locking, no anything.
I got my battery back from my mechanic, who had it on the charger for almost 5 days, bringing it back from the dead (hopefully). Yesterday, I put it in the car, and made some measurements.
The set-up:
I found one of those battery disconnect devices at a local Harbor Freight. That, two battery clamps from a local electronics store, and my automotive Multimeter let me set up to measure the drain while maintaining current flow at all times.
The battery disconnect goes between the negative post and the negative cable, and the multimeter set to the 15A scale "jumps" the disconnect so that when the battery is disconnected via the device, all the current flows through the multimeter.
Got the car all warmed up, and out of its snow-bound parking space. Hooked up the multimeter, shut off the engine, and disconnected the battery. Now all the current flowed through the multimeter.
Initially, current drain was about 0.63 amps. I'm told it takes some time for all the computers to shut down and go offline, so this is rather normal.
After 10 minutes (almost exactly), current drain dropped to 0.54 amps.
After another 5 minutes (15 total), current drain went down to 0.25 amps.
After a further 5 minutes (20 total), current drain dropped to 0.13-0.14 amps.
After an hour, the drain had not changed from the 0.13-0.14 amps seen 20 minutes after shutdown.
While waiting, I had to open the door a few times (my multimeter shuts off after 15 minutes...), and the current would then spike up because of the lights and the DICE circuit that turns the lights on, but it always dropped back to the same current as it was seeing before I opened the door (i.e. no computers came back "online").
Once the battery was reconnected, everything worked as it should. Central locking, lights, even the alarm siren. Nothing was out of sorts.
To me, a drain of less than 150 mA shouldn't cause a newly charged battery to go flat in 42 hours. But I didn't drive the car a long way, nor did I wait longer than an hour to see if something turned on later.
If anyone (Anders?) can think of anything else to test, or a different method, please let me know. For now, the car will sit with the battery disconnected until I can take it for a good drive and back to see if anything changed.
I did find that the plunger switch for the hood was broken off its mount and was sitting - disconnected - atop the coolant reservoir... But I had NOT heard a peep out of the alarm siren when the battery drained.
_______________________________________ Current: 2002 9-5 Aero Kombi Cosmic Blue 2000 9-5 SE sedan, Imola Red 1990 900S Rose Quartz, Auto Past: 1999 9-5 LPT Combi 1999 9-5 LPT sedan 2002 9-5 Arc 1990 900 5-speed 1986 900 turbo Convertible 1991 9000 turbo 1980 99 GLi 1986 900 turbo 1986 900 S 1991 900 turbo 1984 900 turbo 1976 99 GL
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