I also went through lots of batteries until I finally got a battery tender. The Porsche always has power going to the cigarette lighter, so you don't need to hoot it up to the battery all the time (which is hassle). Just plug the tender into the cigarette lighter.

 

If it sits more than 2 days, I use the tender.

 

Tenders the only way to go. Just replaced it in my 2010 and wasn't pleased. My fault, left it off the tender for 2 weeks and it went totally flat. Did upgrade to an aftermarket cause the factory unit seems to be sub-standard.

 

Hate to add to the pile, but I used the Porsche tender that plugs into the cigarette lighter. I had a tiny little motorcycle battery and never had an issue. If you are using a tender and it still dies, you probably have a bad alternator...cheap and easy fix...

 

is there difference wether you plug it in at the cig lighter or hook it up to the battery terminals?

 

I was told direct was better, but it shouldn't really matter. However, if for whatever reason your cig lighter's fuse is blown, you won't know that it is not charging.

 

But that is what a C-tek tender will do for you. It will extend the battery life to about 4 years... just by plugging it in . Can be done in the cigarette lighter, leaving the drivers side window in a crack and plug it in a power socket in the garage.

 

My car is used very infrequently. It is always plugged into the Tender

Same battery for three years now. Actually I have been hoping the battery would fail so I have a legitimate excuse to upgrade to a light weight unit.
Maybe even relocate it to the spare tire area.

 

I guess I am Lucky because I have never had a problem with my Bosch battery even after letting the car sit in the winter for weeks,no battery tender..
I replaced my battery almost 3 yrs ago with the bigger of the 2 sizes..

 

The auto shut down (for using remote key) is 5 days as I understand. I had to change the "factory" battery at 4 years. I do put on tender if I'm not using for more than 5 days (I use the factory cigarette lighter adapter).

I have the car in my garage and don't lock the car doors to save some battery.

Went to non factory battery (Interstate I think).

John in Vancouver

 

I'd get less than 2 years from an Optima. Went through 4 of the between my C2 and Boxster. Went through 2 Costco batteries also, then they quit selling them. I now know why. Porsches that are not driven every 18 hours or so will eat batteries. When the key is off there are still many things happening in the background that are consuming power from the battery. It's only a matter of time before the battery degrades, sulphates and permanently dies. To prevent this and extend battery life to what it should be, use a tender. I plug mine in every night whether I'll be driving the next day or not.

 

+1 Keep your battery on a tender when you're not driving it and it won't discharge. Everytime the battery discharges (even if you can still start the car) it forms sulfates on the plates reducing battery life. If you keep a tender/trickle charger on it, it will not discharge between starts and your battery will last longer.

 

I had a similar problem, but found out the alternator had a short. It would charge when running, but then drain when sitting. I have heard many people have shorts from the trunk/hood/glove box lights not turning off or shorting. You can put a meter between the battery terminal and battery and wait about an hour, then see how much drain you have. Pull ea. fuse and the one that decreases the drain the most may have a short. My 996 can now sit for weeks and have plenty of power. I put the tender on it about once every month or so if I have not driven the car, but it fully charges in a couple hours. My bet is there is a short somewhere in your system. I also installed a 140amp alt as I have a huge stereo syst. No problems anymore! I'm sure it is not normal for the battery to drain in under 3-4 wks. I have a cheap autozone battery and no issues anymore.

 

WOW...After reading all this I must be blessed with my Bosch battery...

 

i would have your alternator checked. what is the voltage when the engine is running? it should be about 13v. anything less than 12v indicates your alternator is not charging the battery while driving.

also, the terminal of the battery needs to be clean. a wire brush socket can be used to clean both the terminal and the battery cable.

a tender is great if you don't drive it much. even if you drive it every week, it will extend battery life. from environmental perspective, it's a good idea not to cycle through batteries every 2-3 years. with a tender, you can get twice out of a battery.

plugging into the cig lighter is fine since the ctek or porsche tender is very low amp. anything over an amp, you'll want to charge to the battery so you don't risk burning out the low power cig lighter harness.