Electrical System

[BeachBunny]

I'm sort of fed up with the DIY stuff with my car. This is the second new battery in one year that it's destroyed (and, no, I didn't leave my lights on or anything). SOMETHING is sucking up the power. I just can't figure out what it is and I've tried EVERYTHING (Ok, that's a lie. Not everything. Just constantly recharging, testing, and replacing). It's pissing me off and making me want to pick it up and throw it like The Incredible Hulk or something. So, I'm going to have a mechanic look at it. Does anyone have any ideas? It could be soooo many things. It's just that I get really cynical and suspicious when I take my car in. Give me your knowledge!

[drz]

Something like this is hard to diagnose. You must have a short or some other resistive path somewhere (I am sure you knew this already). I don't know if an alternator can be partially bad in a way that wouldn't result in a drain battery for several months. How old is the alternator?

I don't knwo what the normal current draw is supposed to be on these cars, but one way to try to narrow down the issue is to start pulling fuses one at a time while monitoring the current with an ammeter and see which fuse closes the circuit causing the big drain.

Does this happen after rain/carwashing? Sometimes seals wear and water ends up where it shouldn't be.

[johnnyBgood]

+1 with drz........

you can have someone that is somewhat mechanically inclined, remove the negative cable on battery & attach a 12 volt test light to it & then to ground.......if there is a short the test light will light......then you just start pulling fuses, when the test light goes out, you have found your short! Note: we know the battery is in trunk, so you will have to have the trunk lid open, therefore the trunk light will be on, causing a draw, so you will have to hold the trunk light switch down with something.......I have some more info: will post later.......

jbg

[johnnyBgood]

ok......Got the Bentley out!

1). Charging System Quick-Check-

Using a voltmeter, you should have 12.6 volts across the battery terminals with the key off & approximately 14 volts with the car running.........if you have about 14 volts with the car running, your alternator is fine.......

Also make sure your battery cables are tight, if loose, they will cause a slight draw & if the car sits long enough, it will go dead......


jbg

[johnnyBgood]

Found this link & this picture too: checking for a short

diagnosing battery drain - Pelican Parts Technical BBS







jbg