Battery problems
 

Twice now I have come out to find my 2018 GT3 with a flat dead battery. I have a tender installed but forgot to plug it in and it was dead after two weeks. I do have a Uniden R3 direct wired in the over head light terminal. I make sure to turn it off when I stop the car. Is this a typical experience?

You must have another source draining your battery.

Do you have a USB cable attached to the center console? that drains the battery too

Also, do you lock the car? I think that having the car locked can make a difference. Mine was good for at least 6 weeks with the car locked. The power ports had turned off and the car started, although the battery was weaker.

No tender for 8 weeks and started right up. Something else is draining your battery.

Definitely not typical. Everyone I know gets at least 4 years from their batteries, and those with tenders get up to 6 years. Was your GT3 custom ordered or did you buy from a dealer's lot? Sometimes a GT car will sit on a dealer's lot for many months, and not all dealers are conscientious enough to use battery tenders to keep the battery fully charged.

All my other cars do fine for weeks without a tender, the AMG's especially. My cayman will go dead after 6 weeks without a tender but this is pretty weird.

Antigravity Lithium battery. Keep reserve charge. Saves weight too. I had issues if I didn't drive for 2-3 weeks on vacation when my car was stock. I can leave it for as long as I want now. Problem solved.

Maybe you actually own a Ferrari.

Haha, partially true, back in ninties mid 2000 yes I would agree, also my 993 use to drain a good size battery in two or three weeks, but modern Ferrari's can sit for a month, no issues.
It's better to have it on a maintianer on cars which aren't driven frequently for the long term health of the battery .
But a 991.2 GT3 should not drain a battery in such a short duration, OP have your car checked.

We have a cool product that can track this for you.... IT will show the drain on you battery and if you take off what is causing that drain it would show you.

But most the other suggestions the Rennlisters offered are on point. We deal with this subject alot being all we do is Lithium Batteries for Motorsports. The most often and highest parasitic cause drains nowadays are the Cameras, Radar Dectectors and the Chargers-USB and otherwise. Also when people add extra accessories to their cars they are often wired in wrong, and defeat the Cars built-in Battery management system that actually works very well to put most the cars to sleep with a low parasitic drain. The 991s are VERY good at putting the Car to sleep, and the batteries last very long. A 30Amp Hour Lithium Battery can last about 7 to 8 week in a stock GT3 without any accessories.... that is a for sure fact being I have that car and have been testing on it over a year and a half...

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My "18 GT3 has similar issues. Batter is less than a year old and dead. No ability to charge. My 19 GTS Targa hasn't had this issue. No accessories in car.

Options for non Li battery ?