Battery charge - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I've had my Boxster for a bit over a year. I once went to go to work and it wouldn't crank. However, this was after I had it in the garage for several days with the doors open (and, as a result, the courtesy lights on) while putting in my racing seat. Last week it got really cold here in Chicago. I think it was 4 degrees with a -15 wind chill. I had some errands to run and the car cranked slowly, but started immediately. I thought it was just the cold. So over the next few days it warmed up a bit (but it IS Chicago, so not that much), but the car continued to crank slowly, but start immediately. Yesterday I got in the car to leave for work, and nothing happened when I turned the key. Everything turned on, but the solenoid didn't click and the car didn't crank. Today I pushed it in the garage and put it on a charger for about 2 hours. The car cranked fine. I drove it for about 20 minutes and shut it off. It started again no problem. I drove it about 5 minutes, shut it off and it started again. Drove it 2 or three minutes, shut it off again, and it started fine again. I took the battery to Advanced Auto Parts and had them test it. They said it was fine, but it needed to be charged. The car sits outside in the Chicago winter in the driveway. Usually, I start it and drive it 1/2 hour to work, then it sits outside again. I drive it 1/2 hour home and it sits outside again. Is it possible that the cold, plus the relatively short drives depletes the battery a bit more every time I drive it? It doesn't seem like the alternator is a problem. In the cold the car has the A/C on, the fan on high, the rear defroster running, lights, the stereo, and maybe the wipers. I don't get any dimming of lights that would indicate a problem with the charging system. What do you guys think?

Well, I've been in Chicago and it really gets cold. I would only use a Sears Die Hard their. Any other battery from Pepboys, AutoZone, etc. are cheap. Go to a Sears and have them check the voltage output while the car is running and a load test on the battery. My bet it's the battery not the car.

How did they test the battery? If all they did was run a voltage test, they wasted your time. The only true test of a battery is to fully charge it, let it sit and cool, and then load test it. You cannot run a proper load test on a partially discharged battery. A load test is a "pass/fail" test, the battery can either deliver the amps or not. From what you describe, it has all the earmarks of a dying battery.......

How old is the battery?

Would cite a DieHard as being superior to any other battery. Sears doesn't make em, they contract them out. Just like they do Kenmore appliances and I have a house full of them and 80% of them have problems within 2 years. http://sites.google.com/site/mikefocke2/batteries has a list of batteries known to fit. The use pattern the original poster has described is very hard on a battery. Every load on it, cold weather, sits outside, no maintainer, relatively short runs and no long runs with few accessories on to really charge the battery. Plus we don't know how old the battery is or even if the battery fluid levels are viewable or maintained. I do like the load test before installing a battery, you should also do a voltage test to see if the voltage regulator is allowing the alternator to try and charge the battery correctly.

if it's 3 or 4 years old, it's time to replace it. I was at wal-mart looking at the same thing and comparing prices with the autoparts stores. Walmart has a maxx battery made by exide(who makes a good portion of batteries), it was $75 with exchange and 3 yr free replacement and prorated up to 7 or 8 years from date of purchase.

if you are planning on using the car this winter, i would replace it. There is no way that battery will make it.

From my experience anything like Die-Hard from sears or a generic from a parts store will all work the same. If your looking for a really good battery buy an Optima, I would get a red top for your Box I ran a yellow top in my last car and it was great also. Don't get one from Wallmart or costco those aren't the same as the ones I'm talking about. If your find an Optima for $120 ish that's the wrong one you will be looking at spending $250-300. Just my opinon you may not want to spend that much.

Since the car is used, there is no way for me to know how old the battery is. I've got maintenance stamps, and a couple of receipts, but not one for the battery. I bought the MAXX from WalMart. Not sure if I should put it in though. I'm leaning toward just sucking up the $75 hit and putting it in. Not sure. They said they discharged it, charged it then tested it, but that's not what it looked like they did. I just looked at the printout they gave me. Although the guy said, "The battery's good, it just needs a charge," the printout says, "Battery charge is low and must be charged to determine condition. Screw it. I'm just going to replace it. If I still have problems, I can diagnose from there.

When you get that cold, the car requires more cca to start. After a few years it no longer has the 495 cca or 700 ca max like when the battery was new. most likely, i'll be buying one this weekend also. I went to put the top in the service position after having the car on the battery tender and it's pretty much toasted. the only thing i go to wally world for is oil, car batteries and mounting/balancing tires(not on the boxster). Surprisingly they do a sweet job on them.

Or test the electrolyte for specific gravity. Sounds like a battery issue to me too. Basically, if the battery is 3 yrs. old or older, it is always suspect. Lead Acid batteries also incrementally lose their ability to hold a charge with each discharge. After about 5 discharges, it's usually shot. This would be exascerbated in cold weather too. Bottom line, quit p*ssing around and if it's 3 yrs. old, replace it and be done with it. Last thing you want in a Chicago winter is to be stranded in the cold by a so-so battery.

BTW, if you have a BatteriesPlus in your area, they have a deal right now on batteries for a 986 for 69.99 ($10 off and $10 mail rebate). They told me they'd load check it, but they did the same check that Autozone did except in the car. They told me that the batt was only about 35% charged. I charged it on Friday, drove it to work on Saturday, and back home today, and it's down that far. He tested the Alternator and the voltage regulator is good, but the alternator is only producing 30amps. I don't know how much it is supposed to put out, but most alternators put out 45 or 60amps in my experience. However, I just checked the Bentley manual and it looks like there are a couple of tests I can do to check the battery myself (specific gravity). I also discovered that my car is missing the battery hold-down(s).

Sounds like two of the three pairs of diodes are gone. An independent alternator rebuilder can easily swap the diode pac on one of these, or do a total rebuild, usually for less than replacement. Batteries and Alternators are interlinked - one goes bad, it overworks the other leading them both to premature death. It's a good idea for owners to regularly check the health of their batteries and alternators before a problem occurs, instead of getting to autozone once an issue arises. This is made pretty easy with some of the testers out there. One I like is the Actron-CP7677-Automotive-TroubleShooter-Multimeter . In addition to all the functions of a normal DMM, it also includes a tach and can test for short cicuits, bulbs, fuses, relays,battery load, alternator load, MAF and TPS sensors and more - it includes a pretty comprehensive manual to perform all the functions. You can even use it around the house. It has 18" leads (incl. aligator clips), a 2" LCD screen that even tells you where to plug in the leads, independent ON/OFF, a Hold button, flip-out stand and shock holster - a lot of tool for the money. Cheers!

That's a pretty reasonable tester. I expected it to cost more. BTW, I didn't mention it, but BatteriesPlus checked the diodes when they tested the alternator and they were good.