Replace or Recharge Battery
 

I have a 2000 Boxster. The previous owner installed a new battery in February 05. (He paid over $200 at the dealer.)

I have had to store my car temporarily while I'm having a garage added to my house. The facility I'm storing the car in does not have electricity available for a battery maintainer. I usually drive the car 3 or 4 times a week and average about 7000 miles per year. The previous owner only used the car on weekends.

When I visited the car on Sunday after not driving it for two weeks, it wouldn't start. I'm fairly confident that it is the battery since all I heard was a clicking sound and the lights on the dash were dim when I turned the key. So, I popped the front trunk and came home. The light in my front trunk doesn't work due to a faulty switch, so I don't think leaving the front trunk unlatched will cause an additional drain.

Here's my question. Should I replace the batter or recharge it? I won't be able to bring the car home for another two months, so realistically I may only be able to drive the car once or twice a week. I'd hate to put a new battery in and have it discharge. On the other hand, my experience is that once a battery lets you down, you can't rely on it.

Take the battery out of the car, bring it to a auto parts store or battery store and have it tested to see if it can take a charge. That should tell you whether you need to recharge or replace. There's no reason to replace a battery that just needed a charge.

Either way, if it's going to be sitting for a month or more, take it out of the car and put it on a battery tender. This will keep the battery from being ruined.

Since you still have battery power it's probably normal drain. I suggest you have the car jump started asap and take it somewhere where you can fully charge the battery. If the battery dies comepletely you may not be able to open the trunk unless you have a trickle charger that plugs into the Cig socket.

Personally, I wouldn't trust a three year old battery. These cars are very finicky when it comes to power supply, as my friend found out earlier this year in his '02 S. A low battery can cause all sorts of havoc with the ECU, let alone alarms, etc. Upon removal from storage, I would replace the battery, but you will need to drive the car for about a week before all systems are go again (DME ready codes).

Do you replace your battery every 3 years?

There is no set age to replace a battery, too many factors influence it's life. You use a battery until it can no longer hold a charge. The battery isn't meant to run the car's electronics, it's meant to provide enough energy to spin the crank, provide enough spark and operate the fuel system until the car starts and the alternator can take over. There's nothing special about the Boxsters needs.

Whenever a battery goes flat it shortens it's life. A three year old batt that is going flat is probably a goner. Maybe this is your opportunity to get a new lightweight Braille battery.

100% agree

"probably" is the key there. There are simple tests for holding a charge that will tell if the battery is truly a goner or not. And the test is free. So why replace the battery if you don't know if it needs it?

If it is a stock Porsche battery, they are simply put, junk. I find the Costco battery to be much better at about $60.

Save yourself some misery and buy a new one and a battery tender if appropriate.

Good luck. :)

Thoughts
 

Can a 3 year old battery go bad? Sure.

Is it the kind that has caps or plugs that can be opened to see the battery fluid level? Check and fill to line with distilled water.

Jump start. Remove jumpers. Seem to rev ok?

While running, have someone sit in the car and rev to 2k and measure the voltage across the battery posts. ~14.4V? OK, alternator seems to be working.

Drive OK? Drive for 15+ miles with a/c off and in daylight. Should now be charged.

Stop. Measure voltage. at least 12.5+V? OK.

Or drive to a battery place and get them to test the battery.

Does completely draining the battery hurt the battery life? Yes. One time fatal? Usually no.

Any aftermarket add ons that are in the car that could be draining the battery? Electronics, alarms, radar, phones, etc?

The trunk lights go off after about a half hour on mine. Been there, done that. Battery wasn't drained when I came out and saw mine the next day with the trunk (or door) still open.

I'd not just go swapping the battery before understanding what is draining it.

There is also a way of removing a fuse at a time and measuring the current drain to see what circuit the drain is coming from.

And if you do replace the battery, there is no need to pay $200 when there is a whole list of perfect fit ones.

Thanks for the comments and advice.

The car is currently in a storage unit that is about three feet wider than the car. The front is facing in, so jump starting it will require pushing the car out. I think I will remove the battery, charge it and have it tested. If it checks out OK, I'll put it on a battery maintainer at my house for the balance of the construction period.

If I buy a new battery, it definitely won't be from the dealer.

This just reinforces my belief that the car should be driven frequently.

If you're going to keep the battery or want to know in the future how good the battery really is check it Old School...If the cells are accessible (and many still are even though the unit looks sealed) check each one with a simple acid test squeeze bulb you can get at any parts store. If the electrolyte has been allowed to go below the plate and you had it on a maintainer, forget it. Fill the cells with distilled water and charge away, then you can check each cell. My battery is at least three years old and it's fine but I'm careful to never let the acid level drop or charge it partially dry.

The Moll battery on my '03 BoxsterS lasted approximately 6 years. I think that is pretty darn good. As mentioned, it is important to check the fluid level regularly and top off with distilled water. The original equipment battery is certainly overpriced. I went with one purchased from AutoZone when the orig bellied up.

@mikefocke... I agree with your testing but your values are a bit off. A healthy battery will produce about 2.2VDC from each of the six cells which are wired in series, so the battery total should produce closer to 13.2VDC. If the battery is less than that, it is either not fully charged, low on electrolyte or has broken or sulphated plates, all of which can happen to a battery over time. So, a range of 11.9 - 13.2 is probably in order.

The same goes for the alternator, a range instead of an absolute value. Bosche rates the alternator with an output of 13.5VDC-14.5VDC. Anything in that range is OK.

Why risk your car not starting or having problems for a simple maintenance item that costs a hundred or so dollars?

Why spend $100 or so dollars before even finding out if there's a problem?

Update - I brought the battery home and put it on a battery maintainer for a few days. I reinstalled the battery this morning and brought the car home. (My contractor doesn't work on the weekend, so the risk of damage is reduced.)

I drove the car 50 miles today in a series of 10-15 mile trips. Unfortunately, the car turns over very slowly (I didn't think it was going to start a couple of times). I haven't had the battery tested yet, but I guess that is not a good sign.

I'm reluctant to buy a new battery right now because the car will be spending most of its time in storage during the next two months. I guess I could take the new battery out, bring it home and put it on the maintainer each time I return the car to storage.

Any thoughts?

It could be the alternator, but it probably is the battery.

If you have the car sitting for 2 months at a time, you should at least disconnect the battery, but if you want it to last as long as possible, it probably should come out of the car and be on a maintainer.

Don't disconnect the battery. Every time the car sits without power, the DME resets to default and you will need to drive the car for approximately a week before all DME systems are "ready". I'd park it and bring along a new battery when you are ready to remove the car from storage. Your current battery is toast.
But do remember, the car will need to be cycled to get all systems ready again (a real problem if you need emissions testing).

There's no harm at all in letting the DME reset.

We don't have emissions testing in our area, so that isn't an issue.

The contractor has completed the foundation work, so I'm hoping that the worst of the construction mess is behind me. At least I can get up and down the driveway without encountering huge ruts. I still can't leave a car on the property while they are working, but I may be able to work out an arrangement where I can drive the car two or three days a week.

Removing and reinstalling the battery when I won't be able to drive the car for an extended period looks like the only option I have. The only problem is that the battery is in an awkward location for lifting. The best technique I have been able to develop is to put one foot in the front trunk and then lift it straight up. Leaning in from one side or the other looks like a recipe for a back injury.