Battery Drain Problem

[ALPacer]

I have a 1978 Corvette that has a battery drain. The battery goes dead within a weeks time. I have replaced the battery with a new one and have had the alternator checked. Both the battery and alternator checked out fine. I want to check for a draw on the system, but I need to know what accessories will be on with the car shut down. As far as I can tell, the only thing that should draw any power is the clock. Anybody have any suggestions? Also, does anyone have the schematic for the alarm system for a 78 Vette? Could this be the problem? Thanks for any info.

Scott
Birmingham, AL

 

[Bob_K]

One way to search for battery drain is as follows:
Disconnect the battery
Remove all fuses
Put an ammeter in between the disconnected battery wire and terminal. If it doesn't read 0 the problem should be between the battery and the fuse box. I don't think there's anything else connected.
If it does read 0, install 1 fuse at a time until you see current flow, that will tell you what circuit to look at.

Hopefully someone with a bit more automotive electrical experience than me can give some better pointers. That's just a generic method that probably needs to be tailored to automotive applications.

 

[firstvette1960]

Battery drain

I had that problem with my last Vette, a 1973 t-bar coupe.
It was the storge compartment behind the seat. The lid had warpped enough that the light didn't go out when it closed. Took the bulb out and that solved the problem.

 

[JohnZ]

Ummm...where do you find these three-year-old threads?

 

[Wayne robson]

may help

I have a 1978 Corvette that has a battery drain. The battery goes dead within a weeks time. I have replaced the battery with a new one and have had the alternator checked. Both the battery and alternator checked out fine. I want to check for a draw on the system, but I need to know what accessories will be on with the car shut down. As far as I can tell, the only thing that should draw any power is the clock. Anybody have any suggestions? Also, does anyone have the schematic for the alarm system for a 78 Vette? Could this be the problem? Thanks for any info.

Scott
Birmingham, AL

following on from robert, you dont disconnect battery, remove all fuses and test acros their terminals for battery voltage with a VOM, or small 12 volt test light, you will find the clock connection with current, if you can disconnect the lead to the clock, and anti theft system. there then should not be current between any of the others with the ingition off, if there is youve identified the circuit that needs further looking in to, alot of fuses have two or three conections to them, by removing them one at a time you can usually find the bad one which is causing your car to battery drain, regards wayne.

 

[Wayne robson]

following on from robert, you dont disconnect battery, remove all fuses and test acros their terminals for battery voltage with a VOM, or small 12 volt test light, you will find the clock connection with current, if you can disconnect the lead to the clock, and anti theft system. there then should not be current between any of the others with the ingition off, if there is youve identified the circuit that needs further looking in to, alot of fuses have two or three conections to them, by removing them one at a time you can usually find the bad one which is causing your car to battery drain, regards wayne.

also i forgot to mention the same method applys when a fuse keeps blowing, caused by shorting out somewhere.

 

[Vette79]

Might want to purchase a Battery Quick Disconnect Switch as a Temporary solution prior to troubleshooting your problem. Rob and Wayne provided great info to follow.

 

[muddywaters]

The cables are long on the C3's, there always seems to be battery drain problems on Vette's unless their used everyday, none of mine were, if it sits, disconnect........

 

[Evolution1980]

Ummm, guys...Just a friendly FYI... ALPacer sold his car back in 2005 and bought a 50th anniversary 2003 model.
Somehow I don't think he's too concerned about the battery drain problem on the '78 anymore. :cool

Regardless... FirstVette1960 and Wayne Robson, welcome to the

 

[76okievette]

Not sure about the 78 but I had the same problem on my 76 and it was the alarm system. The alarm relay was stuck closed and it caused the battery drain. I did not find it the local vette shop did and he replace the relay and all has been fine for a couple of years. My alarm did not work but it was still draining the battery.