I searched the forums and found a few posts about using a battery tender/maintainer (Porsche/Ctek) with the 991, but it doesn't seem to be working for me. I have a Porsche battery maintainer that I have from my 996. I tried plugging it into the center console (smoker pkg) plug, the passenger footwell plug, and the glove box plug. It seemed to me that all 3 did not stay live and shutoff after awhile (quite some time, but eventually shutoff.) The red light on the battery maintainer would light up when I plug it in at first. After some time, the light would go off which seemed to indicate that the plug is no longer live or the battery is above the charge threshold. If I open the car door, then the lights come on and the plug becomes live again, which then causes the battery maintainer light to come on. So, I concluded that the plug was not live and no battery tending was happening. I checked the owners' manual p259-262 and no mention of maintainer/tender. Could someone enlighten me on what I'm doing wrong?

 

I have a battery tender junior and use the center console cigarette lighter. In my case I have found that I have to lock the doors in order for it to work. If I plug in my battery tender and leave doors closed but unlocked, it does not charge. Once I lock the doors however, it begins to charge and continues to do so until I unplug it. I know it sounds weird. Do you leave your doors unlocked?

 

Just picked up my 911_50 and as part of the tender discussion, was told to lock the car, as it will then begin shutting down components that draw electricity over time. Perhaps the tender offers only an amount of current sufficient for a lower draw?

Just a guess - would love to hear the proper answer.

 

I just got my CTEK 7002 this week and plugged it in last night (using the center console since i have the smokers package). I did not lock my doors and this morning the green indicator on the CTEK was lid up that the battery was fully charged...

I do have entry&drive, so don't know if that makes a difference...

 

I did not lock my doors. I'll try that next time. Thanks.

 

I just recieved my ctek, I went and hard wired directly to the battery, just as easy as using a plug, the cord stays in place, I pop the trunk and plug it in.. Works great.

 

If I have it plugged in I wouldn't really care about having it locked to save a little current draw.. If the goal is to save a little 115vac draw it isn't going to make that much difference..

 

I don't have a 991, but on my 997.2, I do not have to lock the doors for the charger to work in either the cigarette lighter or the footwell socket. When I plug it in initially, I have two amber lights. After it has been plugged in sufficiently long to charge the battery, one of the amber lights stays on, and the previously amber light turns green indicating full charge. I have the Porsche branded CTEK 3300.

 

I've had no issues with either the C-Tek or Battery Tender in the footwell or console. Doors unlocked.

 

My 981 center console would stay hot all the time, doors locked or otherwise. 991 I need to lock the doors for it to work, baffled me for weeks to figure this out as it would charge for 30 minutes and the light would turn red/go out (don't remember).

I emailed ctek months ago and they were "looking into it".

Strange that it's different on each 991...

 

I use a Battery Tender that connects to the positive post of the battery and negative "bolt" to the right of the battery and don't have any of these problems. I just close the trunk on the cord and let it charge. Sometimes the old, simple ways work best.

 

I don't have "entry & drive" and I don't need to lock the car to have the charger/maintainer trickle charge the battery, and I use the center console plug.

But there's something odd going on that I've noticed.

Back when I was shopping for a battery maintainer for my new-back-then '05 997, I found that the electronics for the Battery Tender and Sears Diehard Battery Charger & Maintainer were made by the same manufacturer - in fact the plastic housings were identical as well, just different nameplates slapped onto them. So for about 20 bucks I bought the Sears unit, which worked just fine. When I sold my 997 I let a buddy borrow the charger for his bike.

So when I took delivery earlier this year of my 991, I went ahead and bought a new Sears unit, which I noticed had undergone a design change - at least on the exterior with the elimination of the voltage setting switch. The unit now automatically detects the battery voltage and charges accordingly. When the battery is charging, a steady amber light is displayed, and when it reaches maintainer mode a slowly pulsing green light is displayed (part of the design change), which I thought gave it a cool look. The next day I noticed it had gone completely blank - no display. I used a multimeter to verify the output was dead, so I took it back and exchanged it for a new one.

Three failed units later and I'm just gonna get a refund instead later today. Meanwhile I got my old unit back from my buddy (who sold his bike) and it still works like a champ. The redesigned Sears unit (and if Battery Tender is using the identical design) is not recommended. It appears that the electronics are not as robust and easily fail over a short period of time, if you buy one to charge/maintain the battery on a 991. Apparently (and it should come as no surprise really) the 991 places quite an electrical demand on battery chargers/maintainers.

 

BCS14, could you explain what you mean? Other than modern cars having lots of systems that put a load on the battery which can cause it to drain in 2-3 weeks, is there something unique about the 991?

Interesting experience on the Battery Tender as well. The one I am using is 10+ years old (thus the clamps and not the 12v connector), and is still going strong. Hopefully I don't have to buy a new one anytime soon.

 

Yeah sure. I meant that in the context of my post, which was essentially a comparison of my experience using a charger on my 991 versus my 997.

I wouldn't say there's anything unique about the 991 in this respect. As you point out, as cars get more advanced and more computerized their numerous electrical systems put quite a load on the battery. The latest iteration of the 911 is no different in this respect. Which further clarifies what I meant, btw.

Without looking it up, I'm going to assume the battery on a 991 is of larger capacity than the one on a 997 (measured in Amp-Hours or AH for short).

 

Thank you BCS14! I appreciate the clarification.