Battery drains overnight

[Jaydog]

Hello. I have a 98 Discovery (210,000 km). A few days ago I went to start it in the morning and the battery was almost fully drained. All I got was dim dashboard lights and a ticking relay with the key in the second position (nothing happened in the start position). After jumping the vehicle everything ran normally (the battery charged) and I was able to use it for the whole day. The next day... same thing. Now I have been unplugging the negative lead every night so I don't have a drained battery every morning! Any ideas?

 

[joey]

Do you have a light staying on? put a meter on the negative side of the batter and attach the battery wire to the meter... pull fuses till the voltage drops... something is staying on.

 

[Jaydog]

Hi Joey - thanks for the reply. With the key out of ignition and the negative lead lightly tapping the battery terminal I get a little spark. After disconnecting the main fuse labeled: Window Lift, Central Door Locking, Rear Blower the spark is gone. Now if I turn the key to the second position (with the neg. lead attached) the fan in the engine compartment turns on when normally it is off unless the engine is running. I'll see if I can get a voltmeter tomorrow so I can do the test properly and check some other fuses also.

 

[Disco Mike]

When a battery dies, just jumping it will. not give it enough charge to run for days. Take your truck to the local parts store and have them do a free charging system test that must be between 13.6 and 14.4 volts. If the battery is dead, get one with at least a 700 CCA rating, if it is the alternator, don't not buy a rebuilt, they don't hold up.

 

[drbit]

Alternator. Had the same prob on Disco 300. If one of the rectifier diodes goes it allows a reverse current to flatten the battery overnight. Can be rebuilt cheaply. I did my own.

 

[Jaydog]

Update...
Found a blown fuse labeled: trailer lights/auxiliary. Same fuse also runs the stereo/CD player. Both brake controller and CD player are unplugged and new fuse installed. Let's see what happens now. Battery has not been discharging recently but I think it's because the fuse finally melted. Still troubleshooting!

 

[supersgn]

Hello Friends, I recently jumped started another vehicle and accidentally connected the terminals the wrong way and notice that i suddenly over night my battery was drained. any ideas?

 

[Disco Mike]

Sure, doing a wire cross on the battery can effect everything from the alternator to the ECU.
How mechanical are you?