My car has been at Tilleys shop for a little over 2 weeks. He mentioned when he started it after it had been sitting a few days that the battery didn't seem to have much juice and that he had to put a charger on it to test it. I came to his shop 2-3 days later started it, it started up fine, and voltage was around 11.5 with the car off, the voltage from the battery that is. So my question is how long do the batteries usually hold power after the car has been sitting a while. Thanks.

 

Anyone know?

 

C'mon guys anyone know?

 

If the car sits for a while and there is any type of draw on it, it will go down very low. Also voltage that low is something you want to keep an eye on. Usually with the car off the batter should be at 12+ volts. I imagine the weather is a bit cold out there too, so there's probably the likelihood that the battery drained in the cold weather. You also need to have it tested to see if the CCA's are way down after driving it a while, then its time to replace.

 

Alot of the 4th Gen cars have voltage draws when switched off due to the alarm system, etc. Let it sit long enough, and you're dead. When I know I will be letting my 97 SE sit, I plug in a battery maintainer, works like a charm, no more dead batteries..........................

 

I had my Optima Red Top connected to the car while it was garaged for 5 weeks and it fully discharged as far as I can tell, so I guess JFP is right, although I doubt the 4th gen Maxima is different from any other car in this respect.

Question: how bad is it for a battery to completely discharge? Does that hurt battery performance or shorten life at all? It's less than a year old and a damn good battery but it's happened twice to me so far.

 

Running the battery down very low is particularly bad for it, even though Optimas are better than most at recovering, no lead/acid battery can stand that a whole lot, and most never recover from the first occurance.............. You can test to find out what is causing the draw, usually alarm systems, mobile phones, etc, but unless you want to be pulling fuses (or the battery) every time you let it sit, a battery maintainer is the better way to go. Some cars (Porsche, BMW, 04+ Nissans and others) now actually have systems to limit current draw by all but "essential" electronics; but the system will still go dead if left long enough. Porsche and BMW offer and recommed maintainers if the car is going to sit............... I use them on all my cars if they are going to be idle for more than a day or two, works like a charm.............

 

If a typical battery is about 50 ampere-hours it will supply 1 amp for 50 hours, 100mA for 500 hours and 10mA for 5000hours. A guess at the engine off discharge current would be around 50mA for alarm, keyless entry and ECU memory backup which works out to be 1000hours or 41 days.

You can measure the discharge current with an ammeter by taking off the +ve lead and inserting the meter in line. (dont try to start the engine!) your battery manufacturer should provide an RC (reserve capacity) value for your battery which is number of minutes it'll provide 25 amps for.
Ampere hours = R.C. * # minutes / 60

I've left mine for over 2 weeks w/ no problem but then I don't have an alarm.

 

Thanks for the equation! Another thing I thought of is that my hood was open for most of the time, so maybe the hood switch for the alarm (which I believe is messed up anyway) being had something to do with it. Or it's just a 4th gen alarm thing. My Max has every option except TCS so I bet that's it.

I just hope I didn't f*ck up my expensive battery.

 

If i know im going to be working on the max for an extended amount of time, i just unplug the negative or positive terminal so there is no drain on it. Works like a charm whenever i plug it back in to start it, even if its been after a few weeks. Learned this the hard way after draining it the first time.

I have an red top btw.

 

JFP in PA is right - all cars today, not just our max's, are drawing juice from the battery all the time. alarms, clocks, ecu/computer, stereo and things we might add on. if the car sits 2 weeks it could be a problem.

HarrisH said the body shop guy had problems after a "few" days. normally that shouldn't be a problem, but a lot of shops leave the door or hood or trunk open and the lights run the battery down.

 

UPDATE: I tried several different chargers, including a big automatic charger at an auto parts store, and they all indicated that my Red Top was stone cold DEAD. I even called up Optima customer service to find out how to make a warranty claim since the store I bought it from (Batteries.com) no longer sells Optimas. They said to take it to a local battery store and have them do a proper load test.

Well, I took it to a Batteries Plus and they said they would have to charge it overnight before they could even do a load test because it was only showing SIX (6) volts! I went back today and they told me it's fine, it's showing 900 cold cranking amps which is better than the advertised 800 CCA! I saw it myself on their meter. So I guess the battery is fine.

From now on I will be plugging my $25 Craftsman battery maintainer in whenever I park the car for more than a day!

QUESTION: I have some heavy duty (4 and 8 gauge) ground wire (from a grounding kit) in my engine bay, connected to the battery negative terminal. Could all this extra wiring add to the load on the battery when the car is off, or does it make little difference? Thanks for any help.

QUESTION: Since I have a Red Top with an extra set of terminals on the side, my grounding kit is connected to the side negative terminal. This means that if I ever want to disconnect my battery, I have to disconnect both the negative terminals and that's a pain. Is there any problem with just disconnecting the positive terminal?

 

The parasitic loses vary from car to car

 

Question 1: NO difference.
Question 2: NO.

 

How old is the battery?

 

Battery should always read above 12v even sitting. Now whether or not it will work still is something that it will ahve to turn on to find out. If it's below 12v, there's probably a bad cell inside of it.

 

Batteries routinely go below 12V; I don't believe that means the battery is bad. See the other thread: http://forums.maxima.org/showthread.php?t=447499

 

Take the battery to Advance or Auto Zone and have it tested.

 

LOL, did you even read my update?