Battery question

[wvmystichrome]

The battery in my 95 Lincoln goes dead. Kind of common where the car does not get drove a whole lot. Computers drain it pretty quickly. OK I charge it up to drive it the other day. I usually keep a battery tender on it but had not because I had drove it to the inspection station a month - 6 weeks before. No problems. Well battery charger says it found a dead cell in the battery. Well I push recondition battery and it goes thru it's paces for about 2 days and comes back with battery good. I kept the tender on it with no problems. Get in and start it up to go to work Friday and the little battery light comes on. Car kind of jerks a little on idle. Ford tech at local dealership said to test at idle between the positive and negative for charging volts. He said I should have 13 something. I had 14.44 with lights ON and 14.60 with the lights off.

Any ideas if it is the battery or the alternator? I hate to lay out $100.00+ for a battery if it is the alternator. Oh and the battery is about 3 years old.

Thanks

 

[king nothing]

Take it to (insert your favorite parts store here) and they can test both the battery and the alternator in the car

 

[big dad]

If you have a lead-acid battery and it has removable caps you can check the specific gravity of each cell with a battery hydrometer. There should be no more than 25 points difference between each cell. A good battery will read a specific gravity of 12.50 or higher. If there is 50 points difference between any of the cells the battery is toast.

 

[mrlrd1]

Battery light isn't for the battery, it's for the charging system. If it's on, the voltage is low, which means the alternator isn't charging. At idle, turn on the headlights, rear defrost, AC at highest blower motor speed, wipers on high, and leave the LF door open. If you drop into mid 13v range or lower, replace the alternator. It should be around 14.4v at idle with no load. Idle with load less than .5v drop. Loaded at 2000rpm should be within .1v of idle/no load.

A battery with a dead cell is junk. You CANNOT charge it and fix it.

You should replace both.

 

[GeorgiaSnake]

Remember this...the battery is in the car for only 2 reasons. #1 to provide power to the starter to start the engine. #2 to be an emergency power source if the alternator goes bad. Also keeping a charger or some such devise on the battery if the car isn't operated will over time make the battery go bad or otherwise shorten its lifespan. If the car sits unused for some long periods the best thing to do is to just disconnect the battery and reconnect it when you want to drive again. This is what I do when I put my Vert away for the winter, I disconnect the battery. If nothing else, the clock function in my radio will eventually draw the battery down.

The Snake

 

[Stormtrooper5.0]

Don't overcharge!! It will shorten the life and or ruin the battery. It will also cause the battery to gas and release hydrogen gas which can be very bad. If one of the cells in the battery is gone, just replace it now and save yourself a headache. With a rough idle I'd say it was probably the alternator but I can't be positive.

 

[GeorgiaSnake]

quality of idle has nothing to do with the charging system unless the alternator is completely inop and you are running on just battery power and now the battery is almost dead or the alternator is bad and only delivering way less than 10 volts, but then you would be running on the battery until it got too low... Rough idle is not caused by a bad alternator or battery.

The Snake

 

[mrlrd1]

quality of idle has nothing to do with the charging system unless the alternator is completely inop and you are running on just battery power and now the battery is almost dead or the alternator is bad and only delivering way less than 10 volts, but then you would be running on the battery until it got too low... Rough idle is not caused by a bad alternator or battery.

The Snake

Contradicting yourself?

Most Ford PCMs will have all kinds of drivability issues below 11 volts. 10.5 seems to be the most common threshold for electronics glitches. Here's a question for you: If a battery has a bad cell and the alternator will not charge under load, what voltage are you likely to see?