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There seems to be a lack of understanding in these forums that lead-acid batteries have a design lifetime, and that lifetime for automotive batteries is around 5-6 years. There is nothing you can do to extend this significantly.
Not true. Our batteries are not lead acid, they are AGM. And you can certainly extend the life of both with a properly used battery maintainer.
Originally Posted by dday54
I totally understand this....I checked the battery and it seems to be the original. I put a charger on the battery and it charged OK., but I'm going to replace it anyway because I don't want to have problems during the winter months. I'm planning to do the job myself.
Next question is...what is the best brand and battery model (Sealed - AGM) to get for 991.1? I don't want to go to Porsche for this due to price. In reading some for the forums, I'm concern about 3 things:
1) Original does not have a vent that I can see. Is having a non-vented battery very important when shopping for a replacement?
2) Some forums discussions talked about having to reprogram the vehicle when changing a battery...is this necessary on the 991.1?
3) The car has a 750 CCA battery right now...If I install an 850 CCA (95 ah) for example, will this cause any problems (electrical) ?
And thanks to everyone that responded.
Here is the best battery post on RL. Everything you need to know:
AGM (absorbed glass mat) is a type of lead acid battery. It is a more robust design that helps to prevent electrolyte stratification and plating of salt deposits on the electrodes. It’s still possible to shorten AGM battery life by allowing repeated deep discharge cycles, such as would occur by not using a battery maintainer during seasonal storage. But you can’t really extend the life beyond the typical 5-6 years even with religious use of a maintainer.
One thing that may help to ensure full battery life is to turn off auto/start-stop. Using this feature will cause deeper discharge cycles, which shortens battery life even if the battery is returned to full charge. True, the OEM batteries are oversized (and heavy!) to mitigate this. I don’t like the feature myself, but some folks apparently use it out of concern for the environment. Might make for an interesting poll?
As it has been previously mentioned in this thread, car batteries will last around 5 - 6 if kept in good shape.
Don't get fooled.... and old battery can be charged and maybe it will arrive to the correct voltage, but it won't have the necessary ampers and you will still have problems when starting your car.
My car is a daily driver and my drives are very short. Because of this, the battery doesn't have a lot of time to charge (as compared to a long drive) so I use a battery charger at least once a week in order to keep my battery in good shape. Specially on the 991.2, I think that the battery is not charged all the time (or charged at lower rates...) because of fuel economy.
I did a permanent install and connected the cables straight to the front of the car. Charger is left in the front trunk and charges depending on the temperature inside of it (more voltage during winter and at nights when its cold).
Really simple to do and a simple way to make sure you will always have your battery in top shape.
By the way.... if I know that I'm not going to be using the car for at least three (3) days, I will plug the battery charger.
This is the way I connect the cable. The model is a 991.2. Interior looks kind of dirty but this is a daily driver and in my country we just finished a rainy winter (going for spring detailing soon.....).
I use a power cord and the car even has the space to pass the cable into the trunk without a problem.
One thing I do notice - each time I start it, I get a message in the display "Battery Protection Active during parking" or something like that.
I noticed a similar message on my recently acquired 2015 911. I believe systems shut down after the vehicle is parked for more than 7 days. I am looking that up now to confirm.
I also noticed the following in the Owner's Manual:
After you install a new battery, it must be initialised in the control unit.
It "appears" that the 911 negative battery post has some type of sensor. Other manufacturers (VW and Acura that I owned/own) control charging though the ECU which is why a battery type/spec must be entered.
10-15-2018, 12:38 PM
