Cigar Lighter Install I Thought Was a No-Brainer???

[joshnjulie1]

Another quick one.
I should have the negative disconnected too right?
When I put it back on it seems as though the pos cable just acts as a ground and it reads the actual juice of the battery (12.2)

 

[DirtDonk]

No, one cable always has to be connected. I don't think it matters whether it's the ground or the positive. You're just testing for drain by actually completing the circuit with your test probes.
With both disconnected, and only using the test light or meter on one, it's not possible to have any current flow.

And yes, you could easily have a bad cell. But it sounds like with one connected you're getting a flow somewhere. Do the one-cable-connected thing, then start disconnecting things like fuses, extra power leads, and if it comes down to it, even the alternator.
Lots of battery drains turn out to be failed diodes in the alternator.

Paul

 

[joshnjulie1]

Moved this valuable info to "Battery Drain Test & Troubleshooting" in the tech section.