I just bought the CTEK(Porsche)charger for my (new to me)2006 997S.
Have used it for about 5 hours per day for 3 days. Still doesn't indicate a full charge. Should it be plugged into the cigarette lighter,or the outlet in the passenger side of the center console?

 

lighter

 

Why does it matter?

 

I believe the lighter is never switched off, even if the car goes into low power draw mode. Plus, the lighter is much higher current rating.

What does the charger indicate after the 5 hours? Which stage of charging is it at?

On a side note, I use the CTEK but the 7A version. Besides working a little better for bigger batteries (but not as well for super small batteries), it can be used in power supply mode which is very handy for testing things out instead of dragging out the linear power supply. It does float charge at the end differently than the 3A.

 

It is not good to charge lead-acid batteries at high current debits. You should switch to 3A mode and avoid 7A. Even 3A is iffy. The Porsche-labelled CTek has both a 3A and a 0.8A mode.

 

Had mine plugged in to the 997 lighter, took approx 2.5 days for it to go from full charging to pulse maintenance mode. Considering the battery had drained pretty far (the engine cranked over very slowly last time I started it) it seemed to do a good job.

I use Battery Tenders on a 67 GTA Mustang and 05 Viper and am happy with those as well. Hardwired to the Viper battery with a pigtail out the rear that I plug into and use alligator type clips on the 67 with the hood propped up.

 

Thanks to everyone(especially 997 rolls for being the OP).Mine has been plugged in for a few days.
Hope it is fully charged by tomorrow morning!

 

On the Porsche, it never really sits at 7A. It goes into const voltage mode almost immediately and the current tapers very quickly. I have to say the CTEK is extremely well regulated unlike other chargers I have seen. I hear what you are saying but in my case, but it just doesn't get discharged much before going on the charger. In fact, it is a very similar pattern to normal starts.

The porsche alternator regulator is interesting. It really tapers the voltage down fast. After start, it runs at 14.4 to refill the battery at significant amps. Then it tapers down to 13.8 quite quickly compared to other cars. I think this is why the porsche battery seems to discharge faster on non-use - it just doesn't saturate charge for very long. This is exactly what the CTEK solves which is why I think it works so well for us.

 

Why not just keep using the Battery Tender you have now ? I have used one on all my cars and motorcycles and wouldn't use anything else. Here's my setup. Hardwired a powerlet socket to the battery below the front bumper and just plug in !!!!!