Battery Goes Dead Overnight

This is an older vehicle, 1998 Chevrolet Express 3500 1 ton van. The complaint is that the battery discharges overnight, even after replacing with new. The owner had been recently disconnecting the battery overnight to prevent the drain and that did work. Since the van was now running, I drove it into the shop and did a quick voltage check that the alternator was working.

The alternator looked to be doing what alternators are supposed to do. I shut the engine off and opened the hood. I would be charging the battery but after that looking at battery draw so anything obviously on would need to be off. The underhood light was on but I would need to disconnect it for the draw test. The interior dome light was also on even when it shouldn't have been. Dome Override got the dome light off. I wonder if the dome light was the drain. I'll get back to that later after the battery charge.

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Okay. The battery is at 100%. I'll attach the cables and give it a few cranks to dissipate the surface charge. Then I'll wait a few minutes and measure current draw.

8.5 mA is well under the 25 mA spec for this van. It will sit tonight just in case I have an intermittent draw but I'm pretty sure the problem was the dome light staying on. Sometimes a problem is staring you in the face. Or, glaring you in the face.

Thanks for reading!

Kenny@ggauto.repair