I have a battery tender plus that i use on my motorcycle. With all this battery talk i hooked it up to the jag and its in red light charge mode. Flashing green means you have about 85 percent charge so im below that. How l9ng should it take to fully charge the battery or is this charger too weak for the car? Its a 12v 1.25 amp charger. Thanks

 

When I used that model it would always take at least 3/4 of a full day.

 

Yep, 1.25 amp sounds far too weedy to me.
I have a 15 amp tender and it takes about 60 minutes to complete all 7 cycles, and about 55 minutes of that is the last cycle.

 

The danger of using a very low amperage battery maintainer is the possibility that something in the car's electronics stays energized and draws the battery down faster than the charger can compensate. I've had that happen on a vintage Corvette. The ignition switch was worn such that if I didn't get it in exactly the right spot when pulling the key out, the accessories would remain powered on and I didn't yet realize it. The battery depleted, but the 1 amp charger kept going, futilely trying to bring it back up. In the process, it boiled the battery which generates hydrogen. When I went to start the car the next time, it of course wouldn't turn over but instead instantly sparked, the hydrogen exploded and blew the caps off the battery, scaring the crap out of me. Its generally recommended to use a smart charger with enough amps to cover all of the car's electrical accessories (stereo, computer, dome light, etc.) plus some extra so that there is very little chance of depleting the battery. Also you want a charger with some safety features (a "smart" charger) that will not only shut down when the battery is full, but also detect various charging errors and shut itself down is something isn't right. There are quite a few options on the market with around 4 amps which should be enough. The CTEK brand is very popular on this forum. But mainly you just want to make sure to get a good quality unit because there is some danger of fire if a unit malfunctions.

 

Yeah ill keep this one for the bike. Its been 6 hours and its still not up to 80 percent yet. I doubt if the car battery ever had a full charge since i bought it.

 

Thats more of a maintainer than a charger and isn't meant to charge a flat battery. It *may* charge your battery but would take awhile (days maybe?). I have both a Plus and a Junior and they will both maintain the F-Type battery over winter no problem, assuming the battery is healthy/decently charged to begin with. Hell, my Junior takes around 18 hours to bring even the healthy battery to "green" maintain status but once there, stays there.

 

Apologies since this has likely been covered somewhere - I just can’t find it. I have a Ctek (Porsche-branded) charger/maintainer 14.4 V/3.3 A which connects through the cigarette lighter. Should I use it? Is a connection right to the battery better?
Thanks

 

most people seem to use a 5A Ctek , the 3.3A should work however the cigarette lighter isn't powered all the time, when ignition is off it disconnects the cigarette power after a couple of minutes so so can't use that to charge the battery

 

Well, given that your CTEK unit has the Porsche name on it, it likely cost 3x what the identical unit with the CTEK name on would cost (that also stands for the CTEK units with the names of Jaguar, Bentley, Audi, Mercedes Benz, Rolls Royce, Maserati, Bugatti...you can fill in the rest). That being the case, you might think it would work through the lighter socket...but it won't, for the reason already stated: the socket does not remain live.
I have to ask: does your F-Type in fact have a cigarette lighter? Because the "smoker's package" was an option almost never ordered for these cars - a dummy chrome/black lighter-wannabe sits in its place.

It is so easy to permanently wire the CTEK unit (even if it has the Porsche name on it) - and once that is done it is a matter of a few seconds (if you are slow) to connect or disconnect. Instructions in various threads related to "CTEK".

 

As well as the socket where the lighter should be, I also have a 12V socket in the cubby between the seats which might stay powered when the car is asleep - I've never checked that though. However, as others have said, it's more convenient to wire a connector to the car to make charging a breeze.

Another point to consider is if you have an AGM battery - does your Porsche charger support those?

 

Putting pig tail on is really simple!

 

Thanks for all the replies - very helpful.
SCM pointed out the AGM question. I do have a JLR AGM battery. It seems a "smart" charger can be used on an AGM battery but not sure if mine is smart enough. Probably better to start over. I have seen the Ctek MXS 5.0 4.3 Amp recommended.
I said cigarette lighter for lack of a better description - I guess accessory socket is better. I do not have the smoker's package.
The pig tail does seem the way to go.

 

There's a button to select AGM mode on the CTEK chargers. I've got an old Multi XS 3600 CTEK that sounds more like your Porsche one and that has no AGM button. I now have two MXS 5.0s, so I can recommend them.

 

scm: No AGM switch - I will upgrade. Thanks for the help.