Almost no warning: Battery Failure

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Almost no warning: Battery Failure

Postby Old Guy on Thu Sep 17, 2015 8:36 pm

So yesterday the 16th we drove from Oceanside to Las Vegas. No indications last week of any problems (e.g., going to/from the Sunday tech session at Hoehn). When I started the GTS at home in Oceanside is was just slightly hesitant but started right up. I was headed for the gas station. Upon getting gas, it definitely was slower cranking, but started. Drove back home, loaded up the car: same...started, but.... With a 300 mile trip to take I was worried, but all seemed well. Ran at full speed up the 15, making a convenience stop + gas at the top of the Grapevine. Didn't think before shutting off the car. This time it barely cranked, but started. Ran full speed another couple hundred miles; got to our son's in Vegas, fortunately very near the brand new Gaudin Porsche location. No start (but all dash lights and gauges working). Started the car with a Schumacher XP400W "Instant Power" unit (nifty!!) and rushed to Gaudin, arriving just at 5pm. "Failed battery" the service writer pronounced. "Happens all the time." Appointment made; returned early AM today (using the same starter unit...left the hood open overnight to avoid getting locked out of the trunk).

Several hundred dollars later, new Porsche battery fitted and all systems reset or reprogrammed. The car took off to Lake Tahoe; all seems perfectly OK.

So is this how our newer Porsches have battery failure? All of a sudden? Everything seems to be working electrically (radio, gauges, radio, nav) but in the space of less that a day the car simply stops cranking over? No warning messages from the car's sophisticated computer monitoring systems that the battery isn't taking a charge? Just: no-start...that's it?

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Re: Almost no warning: Battery Failure

Postby Jad on Fri Sep 18, 2015 8:34 am

Yep. You actually got more warning than most with a couple slow starts. Once the new maintenance free batteries go, they are gone and won't hold a charge. Not Porsche specific either. Most modern cars are actually over powering the old school 12V battery systems with too many computers I have read. Remember 6V systems?
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Re: Almost no warning: Battery Failure

Postby Steve Grosekemper on Fri Sep 18, 2015 1:01 pm

Yes, super common especially with newer cars and batteries.
That is why when your car goes in for its oil service or low mileage annual service the battery should be checked.
We now use very expensive computerized digital battery testers so this doesn't happen.
They can detect a drop off in performance well in advance of failure.

And the newer batteries are much more expensive due to internal insulation and resistance.
Has to do with all those computers and fancy electronics.
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Re: Almost no warning: Battery Failure

Postby Old Guy on Fri Sep 25, 2015 8:18 pm

Good info, Steve. Thanks. It gets "funnier." We left the GTS in Vegas and drove back our M3 (my plan: get it track ready). So all goes well...but...the morning after we arrive here in Oceanside I go out to start up the M3 and guess what: WOULD NOT START. So what is this, my aftershave? deodorant? The M3 battery dated back to about 2008 so I reckon it was ready to fail...and indeed, it did. New Interstate now installed (thanks to OMS) and all is well. Cost: yeah, in the good old days batteries were under a hundred bucks. Our new one was just over $200. All's well.

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