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Assuming you turned off the ignition. I've never turned mine on to start and it just stays on full time. Also, hadn't seen that version of the CTEK, so let us know how it does.
Yes I only had the ignition on when I plugged in the charger. Will try it in the future without having ignition on prior to connecting to the footwell socket. Car all locked up whilst charging. Car is in my garage. Been out a couple of times over last 5 hours To check everything is ok. Just been out again and battery now in the “care” mode having completed its charging. The CT5 Stop/start is easy to use as everything is automatic with nothing to press.
 

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My question still remains: Can the CT5 charger (or similar), via a cigarette lighter plug connected to its 12 volt output, be plugged into the outlet next to the glove box to back feed the electrical system (the reverse of using the cars electrical system to charge it)? The reason this concerns me is due to the finite risk of finding a completely dead battery or at least a very low voltage and not being able to release the latch on the trunk where the battery is located. In this scenario it appears impossible, unless in a shop, to access the battery for a jump start, charge, or replacement.
 

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Hi Barryng,

There is a procedure to get the front trunk open. I think it is on here somewhere. Basically, you connect a battery to a terminal in the fuse box, which then allows you to open the frunk, thus gaining access to the battery. You would have to use the physical key to open the car door if the battery is flat. But...I think once you gained entry to the car, going on what has been posted here recently, plugging a charger into the cigarette lighter apparently allows charging, so you could then logically assume that you could then use the frunk unlock button on the drivers door sill to open the frunk. The charger however would have to have the amperage capability to power the cars systems up and also power the frunk release solenoid. I have no idea what the car draws just sitting, and if the battery was really flat, the charger is going to struggle if required to power the car, and commence charging the battery. You may have to leave it for a while, till the charger gets some charge into the battery before attempting to open the frunk.

Both the Manual and the " Good to Know " App detail how to attach an external battery to get the frunk open and gain access to the battery. It is a pretty straightforward procedure.
 

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I carry one of these for an emergency power source. As said, you can clamp on to a terminal in the driver footwell fuse box. It also has plugs to directly charge your phone and other equipment.
Got it at Costco for about $60.... :giggle:
29631
 

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Hi Barryng,

There is a procedure to get the front trunk open. I think it is on here somewhere. Basically, you connect a battery to a terminal in the fuse box, which then allows you to open the frunk, thus gaining access to the battery. You would have to use the physical key to open the car door if the battery is flat. But...I think once you gained entry to the car, going on what has been posted here recently, plugging a charger into the cigarette lighter apparently allows charging, so you could then logically assume that you could then use the frunk unlock button on the drivers door sill to open the frunk. The charger however would have to have the amperage capability to power the cars systems up and also power the frunk release solenoid. I have no idea what the car draws just sitting, and if the battery was really flat, the charger is going to struggle if required to power the car, and commence charging the battery. You may have to leave it for a while, till the charger gets some charge into the battery before attempting to open the frunk.

Both the Manual and the " Good to Know " App detail how to attach an external battery to get the frunk open and gain access to the battery. It is a pretty straightforward procedure.
If my Cayman will to be sitting for an extended period of time without the battery maintainer attached, I'm of the habit of leaving the hood/frunk latch open just in case. I learned this lesson the hard way! I should also note this required me to remove the courtesy light bulb from the frunk to ensure that light doesn't run down the battery itself!
 

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There is a specific pin in the fuse box by the driver's seat (at least in the US) for feeding power to the trunk release mechanism. It is described in the GTK manual. If I recall correctly it is identifiable by its red color, and you pull it out or something. Of course if you park the car in a place where you can't open the door then you are in trouble.
 

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Thanks for the suggestions. Although I do remember, even with CRS at my age, about the existence of a specific fuse to apply 12VDC to, I am looking for something that is easy to use and does not require remembering anything specific, a look-up, or special leads to connect to a small point (as could be AAA with only battery jumper cables) . To this end, I ordered two plastic battery holders from Amazon, each holding 4 AA batteries that are likely to always be readily available somewhere. With a few drops of crazy glue I attached the back of one battery holder to the back of the other and have a 12VDC source, albeit limited in max current and total energy. Then it was an easy matter to simply wire the leads with a bit of hit shrink and solder to the leads of a cigarette lighter plug (Amazon). I also put a 30 Amp diode (Amazon) in the circuit to prevent back flow into the AA batteries as this could be very dangerous if I use high capacity un-rechargable lithium AA cells. It and two four packs of batteries are in a quart Ziploc freezer bag in the glove compartment. I am thinking the "idle" current from any minimal car loads in a car shut down for an extended period is very low and can be handled by the eight AA batteries. It has been my experience the car sitting unused for three weeks in my garage still appears to have reasonable voltage and starts instantly so the extended car turned off load must be very low. Additionally, research has indicated the short circuit current for a AA battery is 10 Amps, maybe even 20 Amps, depending on the cell. Therefore, I believe, if it wont damage any of the car's electronics and can back feed the car, this will work if plugged in and then immediately giving the trunk releases a pull to gain access to the real battery. I also think it has the potential to keep everything energized long enough to not loose any memories if changing batteries. The only problem is that I have not had the Kajunas to test it as I am not willing to potentially damage my Boxster, ergo my questions. A potential problem that also must be tested is how much current will be drawn when plugged in after the car has been substantially electrically dead for some period of time. There might be a brief relatively high load until the newly energized electronics realize the car is turned off.
 

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Roadside service with jumper cables can connect right to the (+) that pulls out in the fuse panel and ground on the door. This is what it’s designed for... no special tools or clamps required.

What you’re attempting to do is far more complicated and potentially risky than needed.

Sometimes the simplest answer is, in fact, the best one....
 

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Well, in my car it's on the right side under the glove box, but I use it to charge. I mean the Porsche Charge-O-Mat Pro (which is a rebranded CTek that doesn't seem to match any exact version for sale) only comes with a cigarette lighter adapter. So when I'm gonna let the car sit for a couple of weeks I plug that in and it works great.
 

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My question still remains: Can the CT5 charger (or similar), via a cigarette lighter plug connected to its 12 volt output, be plugged into the outlet next to the glove box to back feed the electrical system (the reverse of using the cars electrical system to charge it)? The reason this concerns me is due to the finite risk of finding a completely dead battery or at least a very low voltage and not being able to release the latch on the trunk where the battery is located. In this scenario it appears impossible, unless in a shop, to access the battery for a jump start, charge, or replacement.
If you mean the footwell outlet - yes that is what I am using as I don’t have the smoker package.
 

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@Barryng, I think I've seen on here somewhere that you can't force enough amps to start the car through connecting through the same 12v port with which a trickle charger can connect. I am no expert on things electrical, however. I did have to replace a battery in another of my vehicles a year or so ago and did not want to have to reset everything on it. I have another hobby that requires 12v power out in the field and with all these batteries around with cigarette lighter outlets, I bought a device where you can just plug into the OBD II port to power the car's electronics. It comes with clamps for a nearby car's battery if you need to do so, but I think this will be the perfect tool if I every need it.
 

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I plug my CTEK into the smokers package 12V outlet in the console. Works fine.
Thanks. Please explain what exactly your doing. Do I correctly understand you plug the 12VDC output of the charger into the console cigarette lighter and it successfully supplies at least a trickle charge to the battery when the car is shut down? I am assuming the charger must be plugged into a 120 VAC outlet when doing this.
 

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I plug the cig lighter adaptor plug into the 12V inlet on the car. Then I attach the wire from the plug to the CTEK charger. Then I plug the CTEK into wall power (120V). Then I close the door on the wire since there is a nice rubber gasket down there and in my experience hasn't hurt the wire. Then I just wait for the LEDs in the CTEK until the green one comes on in a couple hours. Then I disconnect everything in the reverse order, i.e. unplug the CTEK from wall power first.
 

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I plug the cig lighter adaptor plug into the 12V inlet on the car. Then I attach the wire from the plug to the CTEK charger. Then I plug the CTEK into wall power (120V). Then I close the door on the wire since there is a nice rubber gasket down there and in my experience hasn't hurt the wire. Then I just wait for the LEDs in the CTEK until the green one comes on in a couple hours. Then I disconnect everything in the reverse order, i.e. unplug the CTEK from wall power first.
Thanks. That gives me confidence I can back feed the system and 1) not damage anything and 2) drive at least some minimal current back to the battery.
 

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Thanks. That gives me confidence I can back feed the system and 1) not damage anything and 2) drive at least some minimal current back to the battery.
I had the same concerns, but after search threads here and elsewhere figured I'd give it a try.
 

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Has anyone use a Porsche battery charger connected to 12 volt accessory outlet on Cayman 718.
I have the 12 volt outlet located on the left passenger side under the glove compartment. Will it trickle charge when plug in to the 12 volt outlet for long-term duration or connect directly to battery. Please advice before I purchase the charger. Thx :)
Not a problem at all to use the 12V accessory outlet. I have used used it for the last 3 yrs. on my Boxster 718 for winter storage.
 
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