M. Essaie

This would be for the case of garaged, unlocked so no alarm to draw the battery down. After 10 days mine starts up totally normally but now I need to leave it for about three weeks. I have the Ctek but something in me recoils from the idea of a powered device left plugged in and unattended...... I'm thinking that if I gamble and leave it without the charger worst case is it won't crank and I then connect the Ctek for recovery.

BondJ

The Porsche DME began to climb in complexity from the 987.2 but not to the point where a few weeks without a maintainer (assuming a good battery) will matter. For peace of mind charge it overnight before you go away. And lock it. It will go into sleep mode after a few days and draw less juice

vitaminC

And maybe leave the charger connected but not plugged into the wall? That will simplify things if you need a boost.

scootr

I leave mine for 3 weeks at a time without a problem. Ensure nothing is left plugged into the accessory port. You could plug the Ctech in upon your return to boost the battery a little before restarting.

Bxstr

Ideally, if I'm not driving it for a week, it gets plugged in.
Most I'd want to leave it is probably 2-3 weeks. Totally unscientific advice. But if I have access to a maintainer, I'm using one.

Regarding the CTEK. No issues leaving it unattended. My car is parked in a storage facility for 4-5 months every winter, they're all on CTEK chargers. Many of the cars are worth multiples of mine.

318touring

I've left cars plugged in for a couple of months on Ctek chargers, whether for overseas trips or not having the time to drive them.

hueyhoolihan

i've recently let mine sit in the private storage facility for over two months without a charger on it. there were no problems when attempting to start it (2007 base version) up. i've owned it now for about two years and have yet to find it necessary to purchase a new battery.

Antigravity

Modern quality chargers are designed to be left on Cars, brands like CTEK and Optimate say that in the instructions, you can probably download the Users Manual on thier sites to get more comfortable. They also don't charge over 14v or all the time once the battery is charged. So all should be good, but if you don't know exactly how long your battery can stay in a good state of charge in your car without a charger on it, then best to keep it on a (good) charger for sure, because if you over-discharge the battery that is what will damage it, but just as important there are hundreds of threads on Rennlist about when a Porsche Battery is going bad or low on voltage you get flags constantly and chase gremlins. So best to ensure it doesn't get over-discharged and potentially damaged in the first place which is the #1 cause of damage to batteries.

Kitc2246

I had my emergency frunk release cable under the left wheel well re-routed to a more easily accessible location. I've replaced the battery in my 09 and my current 13. The auto Start-stop, which I have turned off, not working is one of the early indicators of a dying battery. Random codes can indicate an immediate need for a new battery. As above I routinely connect the CTEK if not driving the car at least once a week. Connected all the time during the Winter when seldom or never driven. I get my Interstate AGM H7 from COSTCO. I could use an H6. The H8 will fit, but way overkill IMO. My O9 would not start after doing a long detailing with the doors open. My CTEK brought it back quickly, but replaced it. I have a lithium jump pack and a 10 amp charger, but have never used them on the Porsches.

Mathman

I've had mine sitting for 17 days w/o a charger. Started right up. Probably wouldn't go longer than that.

Ubermensch

I would leave the CTEK plugged in. It's literally what the device was design for. I just started storing mine in a location without an outlet to plug into. I decided to install one of these to make sure I can always start it up:

Battery Brain T3-12V Battery Brain Gold Battery Brains | Summit Racing

Essentially it disconnects the battery when the voltage drops below a threshold, but before it can't start the car. Press the remote and it reconnects the terminal and you're off to the races.

PCA1983

3 days.
I use a CTEK 4.3 maintainer, with cigarette lighter attachment.
My battery was built in late 2016, tests good, and is still going strong.
Lead acid car batteries do not like discharging. It causes sulfation on the plates.
I put my CTEK maintainer on anytime it is going to sit 3 days or longer.