Do I have a battery drain?

[gerry100]

'86 Carrera 3.2 , 124K miles

My 86 just killed its third NAPA battery in 18mths ( Napa has been good and given appropriate refunds).

Car sits for weeks depending on weather and saltiness of the roads.

For longer stretches I put it on a tender, but have noticed that this didnt even keep the clock running this last time.

Battery would not take a charge this time, so I'm out to buy a Non Napa battery in the morning.

The last NAPA I returned had frozen to the point of busting out of the case, so there may be quality issues somewhere.

Just wondering if I'm missing something

[HarryD]

You need to test for a parasitic drain.

With the car off, remove the negative cable and check the amperage draw with a multimeter set to 200 ma. The meter goes in series with the cable. You should see not see an off scale reading.

If you do, remove each fuse until the drain stops (you can replace the removed fuse after each reading except for the one giving an excessive drain). That will tell you which circuit is the problem. If no fused circuit, then you will need to look at the unfused areas.

Hopefully someone can help you out with a wiring diagram to find the culprit.

[eastbay]

Until you find the drain:

[Hotshot]

DM me I have all the 86 wiring diagrams.

[EC900]

Definitely something heavy is drawing power and not the clock. It will take some time and patience to sort if in an unseated space this time of year, perhaps keeping the battery on a tender with Neg. disconnected during storage and until drain source is located. Not sure where NAPA sources its batteries, it’s just a label. I prefer respected name brands over generics if I can, as the specs can vary a lot even though the same manufacturer.
I have a 2 yr old Continental battery and kept on a tender, the clock being the only thing it’s powering.

[echecsqueen]

When you open your driver door, does your interior light come on? If not, your switch may not be activating and thus killing the power to the windows, door lock etc when you open the door. The switch is a ground on only. If it gets corroded, it doesn’t make contact when the door opens and then the battery slowly drains. Another test is whether your power windows work with the key out. If they do, your car doesn’t “know” that you opened the door.


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[darrin]

Originally Posted by echecsqueen

When you open your driver door, does your interior light come on? If not, your switch may not be activating and thus killing the power to the windows, door lock etc when you open the door. The switch is a ground on only. If it gets corroded, it doesn’t make contact when the door opens and then the battery slowly drains. Another test is whether your power windows work with the key out. If they do, your car doesn’t “know” that you opened the door.


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This! my trickle charger sensed the drain from the power window relay (as my door lights no longer turned on when the driver's door was open and my power windows were always active, even with driver's door open) and refused to trickle charge my battery. Battery would die within a week or so of sitting. Once a lead acid battery is allowed to drain a few times, it's toast. Easy to check, surprisingly frequently happens and will cause the issue you're describing.