BATTERY DRAIN IN 3 DAYS

[JohnnyJ]

On my 79 Corvette the battery drains if the car is not run for 3 days. Any advice on how to find the problem?

 

[tonyvdb]

First think would be to make sure it's not the battery that is the problem. If you have an amp gauge see if its drawing any amperage with everything shut off. If it is you could start pulling fuses and see if it make a difference. If you find pulling one stops the draw then you have found the circuit that has a problem.

 

[LVMYVT76]

could be a week cell in the battery, disconnect the battery and charge it correctly, and have it checked. If it checks good, you may a interior light that is on, like a map light accidently turned on or a gove box not shut all the way letting the light stay on. I gave up on delco batteries because they would have bad cells in less than 6 months, changed to a differeent company, now no trouble.

 

[1stC3Vette]

First think would be to make sure it's not the battery that is the problem. If you have an amp gauge see if its drawing any amperage with everything shut off. If it is you could start pulling fuses and see if it make a difference. If you find pulling one stops the draw then you have found the circuit that has a problem.

That is exactly how I did it on my brothers '76. Place the meter between the negative battery post and the negative battery cable. Note the amount of current draw, then pull each fuse until it goes to zero or very close to it (.01 or less). Do not try to run the windows or start the car like this.

Good luck,
Dino

 

[Tritium007]

A bad cell will definitely be a problem. A fully charged 12v battery should actually read about 14v when unloaded. A bad cell could still give you around 11 or 12 volts and it looks like the battery is ok, but when it gets loaded down by the starter, it just can't handle the amp draw. Another place to look for the phantom light is on the vanity mirror on the passenger sunvisor if you have one. Good luck!

Mike

 

[6880 Mike]

...Another place to look for the phantom light is on the vanity mirror on the passenger sunvisor if you have one....

Vanity mirror was the culprit on my fiancee's '96 convertible.

 

[JimVette]

First let me say that AC DEelco batteries suck. I have the ZR1, a Trailblazer and a Camaro and none of the batteries lasted more than 2-3 years. Second look at the power window switches in the up position. The only way I found it bad was to disconnect the battery and when hooked up you could hear the switch engage, up side only. Good luck

 

[JohnZ]

A fully charged 12v battery should actually read about 14v when unloaded.

A fully-charged battery will normally show 12.4-12.8 volts across the terminals engine-off, and 13.5-14.5 volts across the terminals with the engine running if the regulator is working properly.