Just got a daily driver yesterday, meaning my 996 Turbo gets to live out the winter in my heated garage. If we do not get snow causing them to salt the roads and the temps are warmish, I still plan to maybe drive it 1 day a week. What battery tender do people recommend while sitting idle in the garage? I have one from harbor freight but not sure I trust it to stay plugged in for days at a time. If I connect it to the battery, is there a way to get the cable out while being able to close the frunk? I don't want my truck light to suck energy out. One plugging into the cigarette lighter would be perfect, so I could leave one of the windows down just slightly and snake it out. Seems only the pricier options have them.

Thanks in advance. Hoping not to spend $100+ on a battery maintainer, but also want the car to start if I decide to use it.

 

i use NOCO

 

NOCO. Most Walmart have them too.

 

This is what I use. Plugged in for 12 years straight without one issue.

 

Same here. Been using this brand for more than 25 years.

 

CTEK is the Porsche brand without the Porsche label. Which ever one you use suggest the permanent connectors to the battery. Too many issue with the internal plug ins timing out or not reconnecting if their is a power interruption.

 

I've got noco and ctek. Noco has bigger wires and more substantial plugs, the unit is better shock protected too. Noco can't recover a dead battery (new ones might, worth checking), but has better restoration capabilities for a drained one. However, if its totally dead, you need it testing to see if it recovers.

Also, make sure you get a proper rated charger for your battery, the smaller ones are for bikes and the bigger ones are for trucks, so you want something mid range, I use 5A on my cars.

I would recommend getting a battery tester, beats waiting for it to fail.

 

I've been using a CTEK ( 3300? ) for many years in fact on my second one. Same as Porsche branded for like 50/60 bucks? I use it a lot in winter as the car mostly sits.

Just don't plug it in with the prongs reversed into an AC socket. That ***t hurts. Doh.

 

Since 2001 I am using the jr battetry tender....Still working!!!!

 

Our 996 turbos do not appear to have large enough alternator nor a smart voltage regulator leading to chronic under-charging. so it's a wise to monitor your battery
I've met many cars at porsche meets who are replacing their batteries every 10-18 months. Sometimes the dealership also sells them a new alternator.

I have run a lot of Off-grid marine engine and house load battery systems. The steps below may be more than you want to read. ha.

1. I would not use a cigarette lighter input.
Battery chargers can suffer voltage regulation problem or pass-through a transient AC voltage spike. A short spike might not bother your battery but it will likely blast some other parts of your electronics. It only takes one voltage spike to really mess up your driving season.

The best is to connect direct from charger to the battery with medium-gauge short wires. it's not difficult to open the frunk and twist the 2 plastic connectors giving full access to the battery. Then use a cheap voltmeter to check the battery directly on the battery lugs before connecting charger. Opening the top also forces you to look at the terminals and surroundings for trouble, especially leaves clogging the drain below.

2. When to charge?
using a voltmeter directly on the lugs and waiting a few hours after driving - if you see 12.2 to 12.3 volts call it good. if less voltage it's time to charge. if less than 12.05 volts the battery is likely unreliable or dead. You can also watch the voltmeter instrument while driving, the voltage should start 14V but roll off to 13V as time passes if the battery is good - but accuracy is suspect.

3. What battery do you have? maintaining a big 80-100Ah AGM is different than a 40Ah FLA.
The AGM has a lot of reserve power and life without liquid maintenance, but it requires a definite charge profile (more expensive charger). You must have an AGM charger, the larger the battery the larger the charger needed (my 80Ah Porsche battery initially needs 30 amps to Bulk up). The AGM requires BULK (14V+) -ABSORB (13.75V) -FLOAT (13.2V) current, then OFF when approaching 100% SOC. AGM dies soon if allowed to sit in a discharged state. AGM does very badly if only trickle charged; I've seen big expensive new heavy quality AGM batteries die after one winter sitting on a trickle charger.

The FLA is a simpler battery, bulk charge 13V then trickle at 12.5V but you must monitor the acid level in every cell - trickle charging can boil out quite a bit of acid, even if just in one cell.

Lithium is another world and not a good technology for our cars unless you are racing and swap batteries at pit stops.

4. When to stop charging? disconnect the charger and let the battery rest a while. if it is holding 12.2-12.3V call it good.
Because I've seen so many batteries ruined by chargers (even expensive Victrons and Mastervolt) that didn't stop charging - I always disconnect the charger when done.
Replacing a battery is an expensive pain, including transporting the old and the new unit, then lifting the unit in and out of confined space without spilling acid or damaging your back or shoulders.

The small devices giving battery "health" are not reliable. The health device will call a battery good until the day after the battery is dead. Measuring charge capacity requires a 10-hour or 20-hour test.
Current-shunt-counters can be good if the battery Peukert-factor is known. Otherwise the voltage measuring system above is the best guess for battery charge-state.

I routinely get 15+ years life from my batteries. Lots of my marine systems were critical or remote, so needed to be robust.
Doing all the above may be more trouble than you want just to avoid Dead Battery in a far away parking lot.
Enjoy the maintenance of your Porsche!

 

Deltran Battery Tender, Noco, Ctek... All good.

For a quick pick, can't go wrong with this:

 

I use the Porsche battery maintainer that plugs into the cigarette lighter. I keep it plugged in unless I'm going out again soon after a drive.

 

I went from the Porsche one in the cigarette lighter, to the CTEK, to the Battery Tender, and now use NOCO, which I like the best. I also bought NOCO jump packs for everyone in my family - they work awesome too.

 

there is a porsche one for sale in marketplace.

https://rennlist.com/forums/market/1425885

 

Thanks so much for all the suggestions. My red oil light and battery light are coming on occasionally whenever I put the headlights on. It's strange. I can turn on the fog lights and HVAC using much more energy, but the low beams seem to trigger it. The car was at a body shop for a couple months where I know it was moved around a bunch without being driven enough to charge the battery.