Good evening.

I have a 93 Vette. My battery keeps draining. if I drive the car fairly regularly, everything is fine. If i let it sit for awhile (like now because of the weather) the battery dies. I have a trickle charge (which I was getting ready to hook to the battery tonight) but the battery is dead. This has happened quite frequently. Any thought?

Thanks

 

do you have any aftermarket electronics in the car?

 

It sounds as though your battery is shot. Try giving it a good charge on a battery charger and see it will accept the charge. If not, time for a new battery.

If it does accept the charge, and seems to be OK, use an ammeter on your positive battery cable to see if you have a high parasitic drain on your electrical system.

 

Yes I do. An Alpine head unit.

 

How old is the battery? Sounds like time for a new one.

 

Actually not that old....

 

yep.

I replaced a few batteries after letting it go too long without a trickle charger.
If the battery is good just use the semi-perminant wire leads on your battery and plug it in to the charger whenever you know its going to sit for awhile.
Just make sure its Fully Automatic trickle charger like the Battery Tender Jr, thats what i have along with a few others for my quads.


The OEM stereo draws a charge (clock) as well as other things I'm sure.

Jim

 

NEVER let lead acid batteries sit, they self discharge even disconnected and lead sulfate collects on the plates and ruins the battery. Car batteries are not deep discharge batteries and every deep discharge reduces the amphour capacity until you have essentially a motorcycle battery and then a door stop. If you let your car sit for long periods (4+wks), connect a battery tender which keeps the battery charged up. Batteries kept charged experience normal battery life, batteries deep discharged experience short life.
You might also have excessive leakage current and aftermarket electronics can be the source of the leakage. GM says leakage current should not exceed 50 milliamps. My 87 draws 27 ma. and I have never had battery problems. At night, look for underhood lights, vanity mirror lights, door map lights, console lights and don't leave your key in the ignition as this keeps the antitheft module on.
You should measure the leakage current by disconnecting the neg battery cable and connecting an ammeter from the cable to the battery post. Pull the courtesy fuse so you don't have courtesy light current and have to wait for them to time out. If you have more than 50 ma. leakage, pull fuses one at a time and if one drops the leakage current, that circuit needs further investigation. Try disconnecting your aftermarket radio too. It isn't a good idea to put an ammeter in series with the positive battery post because if the wrench touches metal you will short circuit the battery. Always disconnect the negative terminal first as the wrench can touch metal with no hazard.