My battery won't stay charged.

That is, it won't stay charged when the car is parked for 4-5 days or more.
This car has been a project car for 2-3 years that I will work on for a while then drive as weekender for month or two while I collect parts for the next project.
I have a couple of suspected causes in mind and hope you "R-listers" can point me in the right direction.
First is the battery. I've always used Ultima batteries (I'm on my third with this car) but this "charge and drain" cycle has caused these batteries expire early - so says the dealer I've bought from. He said maybe my charger was too aggressive causing the battery to "cook" out the electrolyte. I bought a new Sears 2/10 amp with this last battery and I'm still having the problem. Yes, it's a "RED" top.
BTW, the car itself does a fine job of keeping the battery charged as long as I drive it every few days. Unfortunately that's not always feasible.
The next obvious choice is that something on the car is "ON" and slowing running down the battery. Here's where I could use some help. I've pulled the fuses for the normal stereo/clock, didn't seem to help. Besides the battery shouldn't run down in a few days with those...
What is the correct way to run down a circuit that is malfunctioning? I just got a nice digital multi-meter, but the instructions are basic at best.

Sorry for the long post. Any/all ideas/ suggestions welcome.
Are these cars just hard on batteries?

m

 

This may sound absolutely ridiculous but a couple of years ago my battery kept running down after a few days and I took it to the local shop. Turns out someone had pushed the light just in front of the glove compartment into the on position. It was staying on and draining the battery. Ridiculous I know, but you might check it.

 

It sounds like your alternator is fine but something is drawing too much current all the time. I'm sure even with the car off and the keys out there will be x amount of current draw but very very little to ever cause the battery to go dead. Now you have me wondering what that current draw is. Both you and I should check our cars by disconnecting the negative connection to the battery (with the car off of course) and hook up our meters in series to re connect the wire and see what kind of current the electrical system is drawing. If there is a difference between our cars (and it shouldn't matter much if our cars are different) that you have something going on. I will do this test this weekend sometime and let you know what I get.

Brent

 

Brent -
Thx for the help.
right now the battery is out of the car, and charged.
I'm going to check the voltage every 12 - 24 hrs for 4 or 5 days and see if it drops - that will answer at least part of my question(s)...
M

 

This happens to me too. i bought my car as a project car and drive it for fun only on the weekends. It can only sit for a couple of days before the battery goes dead. I took out the fuse for the radio/interior lights as I know there is a problem on that circuit but the problem persists. The only thing I can think of is the clifford G4 alarm system is drawing too much electricity. I think that if i were to drive it every day it would be fine because i drove it all over the place last weekend and didn't have any problems. I'm going to get a meter and perform the same test. But for now I keep it plugged in to a battery maintainer.

 

Timing is ironically perfect - my humble 82 SC is experiencing this over past two weeks - charging pulling 4+amps at each sitting, will start - but leave for 4/5 days and it's dead!!! In fact it has always been like this now you mention it.
Interesting thread this...keep talking - Ta
Andy

 

Well here's an up date.
BTW, I said my battery is an Ultima - it's an OPTIMA.
Voltage at the terminals with the charger attatched is almost 14 volts - just what it should be. Initially after charging the battery (unhooked and out of the car) is 13.5 volts. After 24 hours it dropped to 11.3 volts and has remained at 11.3 volts for almost 48 hrs.
I think i'm going to contact Optima batteries on Mon to see if they will honor their 3 year replacement guarantee.

 

Mitch, I just checked the current draw from the battery with the car off and the keys out. With the trunk light switch defeated there was 0 current that the car was drawing. Just with the trunk light on it was .71amps which is about right since my battery voltage is 12.66v and the bulb is 10watts. So 10/12.66= .79amps so the bulb is really 9watts under load. Either way there should be no current draw when the car is off and the keys are out. Did you ever check the voltage when the car is running? If not more than 15v and there isn't any current draw when off then your battery is suspect. It already seems suspect since the voltage is going under 12v but I think at times mine will be in the high 11's. My car has sat for way more than a week at a time before attemping to start it and will start right up with no battery tender to it in between. You might want to take your battery to your mechanic where he can check for current capability under load. Just checking the voltage won't tell you if your battery is bad. Then let us know,

Brent