Car Battery Problem

Went out to start the car the other day and discovered the battery was flat.
Had the break down out, the jump started  the car with no problem (so that ruled out the starter motor and solenoid). I put a multi meter on it and it was putting close to 14.7v in (so not alternator)

I sat with car running to put charge in the  battery. I disconnected the negative lead, checked what the battery was holding 12.85v. The breakdown person said to perform a parasitic draw test, so I did that and found no problem.

Was told to leave negative lead disconnected, the battery should hold its charge with that lead disconnected. Went out the following morning and it had lost charge again, it had dropped down to 12.08v. Just managed to start the car, went for a longish drive. I then disconnected the positive as well, just in case. This morning it was at 12.42v

Took the battery to Euro Car Parts for them to put it on a drop test. Had replacement battery.

This is a useful guide:

12.65V - 100% good
12.45V - 75% condition
12.24V - 50% condition
12.06V - 25% condition
11.89V or less - utterly dead

If your battery shows anything less than 12.4 volts it's time to replace it.

With your engine running, your battery should read 13.7 to 14.7

Here's a link to a YouTube video I made:


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