junjunphoenix

Battery is good. Alternator is charging.

But cold crank in the morning is weak. Sometimes not enough to start the car.

I know there could be a million reasons for the battery drain, but are there a few primary reasons (historically) which happen to recurr more frequently than others?

Thanx.

freakness

How old is it?
How are the connections at the battery...nice and tight ?

junjunphoenix

Yeah, I tested each cell in the battery. Water level is high and each cell tests fully charged.

Connectors are cleaned and tight. But you're right, maybe I should clean them off some more ... just to be certain.

freakness

simply won't hold that charge for very long. Is it cold where you are ?

Shard7

their higher internal resistance limits their cranking current, especially when cold.

A general rule of thumb is 5 years in hot climates, 6-7 years in more moderate climates. Beyond that, the battery will fail you sooner or later (cold temperatures will cause the battery's weakness appear)

If it's the original factory battery in a 99, you're definitely due for a new one. You're gonna need to replace once during the life of the car, so might as well get it over with and avoid being stranded.

A4SilverT

You are locking the car, aren't you? Paradoxically, when the security system is ON, the vehicle uses far less power. Apparently several of the more power-intensive subsystems go to sleep when the vehicle is locked. Left unlocked, even a good battery will drain in a week.

Other common causes:

Aftermarket electronics;

Central locking system.

But I agree with freakness. It's likely an old battery that's not holding a charge.

And you did look at this in the FAQ, right?

<a href="https://forums.audiworld.com/a4/msgs/2456949.phtml">Bad Battery? Parasitic Current Draw? How to Troubleshoot</a>

DevilAudi7618

This might be a silly question but....
does it matter if you are locking the car with the remote, or manually with the key? Having lots of problems with my battery not holding charge also.( https://forums.audiworld.com/18t/msgs/3353.phtml ) My remote died and rather than fork out the $200 for a new one I just manually lock it.

A4SilverT

I'm fairly certain that the security system is armed and everything else is in sleep mode.