Good battery not keeping charge

Hi All I have an issue with the car battery not holding a full charge. The battery is new and I do not suspect it. I suspect something is draining it while the car is standing. If the car is not used and in the space of 24 hrs, the battery will go from 12.6v, which is a full charge, down to 12.35v which is somewhere around 60-65% full. The car is a 2001 C2 tip, is kept in the garage, not locked or alarmed and the key is taken out of the ignition. Any ideas would be welcome, thanks.

Hi! When the car is running does the volt meter show at 14v. If its not around the 14v mark it would say to me your alternator is the next suspect part you need to investigate! Jack

The alternator shows 14v and more when started and settles on just below 14v. My issue is that the battery is dropping from full to 60-65% while the car is not used for a day.

I did think of the alternator because they are susceptible to damage from water ingress and at some stage I believed that it was the culprit, but it has since behaved better. I'll explain why. Have you noticed how much water gets trapped in the rear lid after washing the car? When I open the lid after a wash there is an unusually high amount of water that falls out of the lid. Some of this water will fall onto the alternator and if left there, will eventually rust and/or compromise the alternator's bearings, brushes and electronic components. I now place some plastic over the motor, under the lid to wash the car to keep the water away mainly from the alternator. After finished washing I take the plastic out and run the car proper to dry the remaining water. Previously the water did effect my alternator, but I think it has survived since I have been keeping it dry, the voltage output is currently showing just above 13.5v which I am told is the minimum to expect from a good alternator. BTW water entering the air filter is not a problem as it just runs out of holes on the bottom.

I believe you need to lock your car in order for it to shut down most of it's electronics. After a few days of being locked it goes into a power save mode and even turns off the electronic locks. -S.

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Thanks Ubermensch, I'll try that and see what difference it makes.

Yes I heard the same. To lock up th car even in the garage when you leave it for any lengh of time. Saves on the battery someway or another.

Do you have a Boomerang installed on the car? These tracking systems are known to drain batteries as they never allow the car to fully "go to sleep".

These cars require a battery tender if they are not a DD. They have lots of things going on when parked and not running that consume current.

Mine does exactly like yours does, I think it's normal.

just wanted to put it out there, check the date the battery was made and sold to you, plenty of times a battery's have sold but has been sitting on the shelf to long and has to be exchanged for warranty.

No boomerang or similar device installed. The car is almost a daily driver, I don't go for more than 24hrs without finding a reason to drive it. I'll lock it from now on between drives to see what difference that makes and will report back.

Locking it will turn off some systems immediately and even more systems after 5 days. However if yours is running down in 24 hours I would say something is going on. I always lock mine every time. But mine can easily sit for a week without any issues. Just remember that if it sits for over 5 days your key fob will not unlock the door. You must unlock the door with the key and then get the key in the ignition and turn it at least to the first on position within about a minute or the alarm will go off. I would put it on a battery tender every night until you get it figured out.

I've recently experienced some trouble with the car starting. The last few times I have started the car it is having a hard time turning over. I checked the battery voltage when it was running and it was at 14v but before I turned it on it was 11.9v. Is this the same issue that you have had? I guess I should probably get my battery checked out

I've been having the exact same issue ever since a new battery was installed a month or two ago. After a night on the charger, car would start and run fine, positive charge on the gauge, alternator tested in spec when the battery was replaced. Went back the the indie who checked the battery, turns out there were three dead cells. Unfortunately I'm having the same problem with the second battery but have been away for the last few weeks so I haven't had a chance to deal with it. FWIW all was well with the original battery I replaced it as preventive maintenance....Oh well, i guess, If it ain't broke...

yup battery's sit on the shelf for a long time, and are only cycled for new ones every couple months. and depending on what type of cell it has that is not good for the battery

Thanks for all your suggestions. Have taken the advice of locking the car when not in use, even if it's for an hour or overnight at home in the garage. My findings are that the battery does not drain as much when the car is locked as it did when the car was left unlocked.

FWIW, some years ago, the EPA mandated a reduction in the amount of lead battery manufacturers could incorporate. The purpose here was to reduce the amount of lead that ultimately ends up in landfills. One of the unintended consequences seems to have been that today's batteries will not fully recover from a complete discharge, in spite of an extended re-charge effort. Could it be that your "new" battery has been discharged at some point? Just guessing. relinuca

Mine has sat for over a week maybe 2 and has been ok, put an amp meter on the neg side and pull the fuses one at a time till the draw goes away. This will atleast tell you what circuit is causing your extra batt draw.

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When you say "put an amp meter on the neg side". How do you suggest I measure it? Are you saying measure by removing the lead and putting the meter in between the lead and the neg battery terminal? Thanks. Regards Ant

yes an Amp meter goes in line NOT ACROSS.... so disconnect the neg lead of the battery. Place a 10A meter between the battery and the neg batt lead. Take note of the current draw. Start pulling fuses one at a time till you see a substantial drop.

When I was having trouble with a convertible top this past 2 weeks, I needed to check my battery. I took it to Pepboys and they checked it out on a machine for free without removing the battery from the car. Their finding is I have an excellant battery. BTW a Porsche dealer told me I needed a new battery almost 18 months ago so I took it to 'Pepboys' and they told me the same battery was in good shape and that I didnt need a replacement. Needless to say that I never went back (or ever intend doing in the future) to that particular Porsche Dealer again. Once bitten twice shy. So what I am saying is that Pepboys will check your battery out for free as i think most auto sales places will if they think they have a possible battery sale on their hands.

My 98 has a Quicktrack system fitted. Now I know why my battery drains when left for some time. It had me stumped.

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Do you still have the original battery?

As some others have said, improper storage can make even a new battery not hold a charge, I have had this issue a few times in the past. I would also suggest a full AVR test that will test the battery, alternator, and starter and idle and with load, as well as measure battery CCA's and test for parasidic draws on your electrical system.

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I was having the same problem & this is what I finally did. Now, it's ready anytime you're ready (mine's set up to where you just plug it in or un-plug it) to me that's alot easier than having to fool with the terminal clamps! Even though I usually drive it at least every couple of days, this is quick & easy & you have a Full Charge! jmo