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[Capritain]

Haven't drive my car for a year now but start it up once a week.  Noticed the battery was weak/dead.  Autozone charged it confirm still good.  Car start right up, but once let go the + and - cable, it dies.  Bad alternator?  I just replaced this last year!

[Rocketman]

It's very harmful to remove the + or - cable from the battery while the car is running, that's a trick you could do with older generators but not alternators. Alternators require a field voltage from the battery to remain running

Is your battery light on? If not your charging system should be working properly

[mitch1204]

Doing that creates arcs and can send a power surge to the sensitive ECM.

Get her running and check the voltage at the battery. A healthy alternator will put out 14.0-14.5V.
13.0V is worn and close to replacement time.

Now a battery sitting in storage, especially exposed to cold weather will discharge over time. Once it completely discharges the battery will never take a proper charge again. Partially discharged is okay for a recharge.

Always store a battery disconnected at room temperature in a well ventilated area. Trickle charge it at least once a month.

Wal-Mart sells a $20 Schumaker maintenance charger. It turns itself off and on as needed and keeps a battery in good condition.

Test your alternator like I posted but I wouldn't be surprised if that battery doesn't charge well.

[Capritain]

OK after kids in school, new work hours finally getting back to the Capri game.  Couple years ago replaced alternator and new battery last year. Took the alternator out also still have the old alternator. Tested at autozone both is good 14-+V.  At the battery terminal only 11v. Sooooo comes down to wiring.
Please help me begin where to start. Look at the connector seems to be clean of any rust.
How far can I drive with a full battery charged?

[Capritain]

After getting the confirmation that both alternator is good I put the original back on. Made sure the belt is tight. Start up wola! Meter jump up as it should. Check meter at the terminal, YES 14v! Now I can beginning working on it again with little short time before the winter.

[Capritain]

After getting the confirmation that both alternator is good I put the original back on. Made sure the belt is tight. Start up wola! Meter jump up as it should. Check meter at the terminal, YES 14v! Now I can beginning working on it again with little short time before the winter.

[Capritain]

WTH! Park for couple days battery is dead. Jump start and noticed meter was week. Check voltage and it's only 12v. Engine of and is 11v. Could it be one is warm the belt loosen?

[blueamber]

A good battery should never read 11 volts, unless there is a significant current draw off the battery.

Just wondering what alternator you are using, the bosch or mitsubishi?  Bosch has a visible cooling fan.  I had a bosch go bad once on a 91, measured 14.5 engine on, good battery, yet battery drained within a few days of non-use.  Turned out the voltage regulator on the bosch had gone bad, and was allowing current flow, engine off, draining the battery.  I tried 2 times replacing the voltage regulator, kept getting defective China ones, so gave up and converted bosch to mitsubishi plug and installed a mitsu I had laying around.  No more issues.

If you actually are reading only 12 volts at times with the engine on, and this has happened with both alternators, I'd also consider the connector at the alternator to be flakey.

Something else that doesn't exactly fit with your description of events is a light bulb in the trunk or glove box staying on all the time due to a faulty trunk or glove box switch...

[Capritain]

Oh sheet! I totally forgot about the trunk. I just remember i opened it earlier. OK so battery fully charged 14+v engine on. 13+very engine off. Gonna leave it over night see if it discharged this fast.