Removing a 996 Battery

I went to remove my battery to charge it up and also clean around inside where leaves can collect and the alarm went off after I disconnected. The car was obviously unlocked and the alarm unarmed. Any idea how to shut the thing up?

Some UK cars have a supplemental alarm siren with a built in rechargeable battery. Also a tilt sensor. You need to turn the key on before you disconnect the battery cables or the siren will go off. There must be a high rate of battery theft in the UK.[ ] We do not have this in the US. We just disconnect the battery. Since your year has an electric front trunk release do not close it when the battery is disconnected.

Just the job, thank you!

Anyone know? Can the battery be charged in situ or is there risk of damage to the ECU? My (cheap & basic) charger puts out about 13 volts but I imagine this could go up under load(?) Thanks, Conrad

I have charged my battery many times while it was still hooked up. Sometimes when I go to my local dealer they have a car in the showroom with a charger like mine connected and the battery cables hooked up.

Safer to use a Battery Conditioner if you are thinking of doing this regularly - these are designed to be left connected to the car indefinitely.

A basic battery charger is a pretty crude affair and you're relying on the battery itself to act as a voltage clamp so that the AC ripple inherent in any simple transformer/rectifier does not cause problems. The ability of the battery to do this depends on its condition and the more powerful the charger, the lower its source impedance is and the more important it becomes for the battery to do this job. For that reason, I would always disconnect the battery before charging it. Whether you remove the battery depends on how well ventilated the charging space it. In my case, I needed to remove it to clean the area around it. A well designed electronic control unit will be protected against over-voltage and reverse polarity but like the Cambridge Audio hi-fi amplifier which blew up when I intentionally tested the short circuit output protection and found it didn't work, it's much better not to go there. Far better, as Mark Bennett says, is to use a battery conditioner which is a regulated DC supply which charges the battery first using a constant current supply to load up the battery independent of the voltage it is presenting, then a boost phase to ensure the battery is fully charged followed by a holding phase where the charger charges at constant voltage (13.6 - 13.8v) to keep it fully charged ("trickle charging"). These chargers can be left connected indefinitely without disconnecting the battery. The 996 has sensible power saving measures to shut down electrical systems after a few days to prevent battery drain. One of my other cars, an SL55 AMG, will happily flatten one of its two batteries in 7 - 10 days so I always connect it to one of these chargers when the car is not in use. The make I use is called Mascot, Type 9640, available for about £27 online.

Ive used this http://www.halfords.com/opd_product_details.asp?id=16907&type=0&cat=28 for a few years since i was stranded with a battery that wouldnt turn the car over. Inexpensive and does the job well

Thanks for all the info. guys. Battery conditioner no good for me though as I don't have permanent power to my garage. Conrad

I have power in my garage, but I believe there are several solar powered trickle chargers available. If there is a discrete location for the panel, this has to be the answer. In fact I feel like buying one just to take advantage of the free electricity!!!

I've actually got one of those; used to use it on my 968 because the battery voltage would 'plunge' after only a relatively short period of non use - particularly in the winter - such that the starter would struggle to turn over the engine, invariably requiring a re-charge/jump start. Use of the solar charger certainly worked, but at the time my car was parked outside in the light. I'm wondering if there would be sufficient light in my garage through the small window for the solar panel to have any effect? I would certainly recommend them for use outside though.

Can't you mount it on the outside of the garage so that it faces south-ish, out of reach of idle hands and then just run the cable inside? Surely someone else out there has done this? In fact, you make a good point. Now that some new cars are available with a solar panel in the sunroof, used to run the air con when the car is parked up, why not have a solar panel fitted to keep the battery in tip top condition?

Good idea, but how do I readily feed the wires INTO the car and then lock it with the windows shut? I wouldn't ever consider leaving the car unlocked even though it is in a 'secure' garage. I understand a higher capacity Porsche battery is available and this might be the way to go.

The cigarette lighter is always live, so you can route a flat ("bell wire") cable over the top of the window glass. Alternatively, the battery is actually open to the elements, so you can route a cable down in front of the wipers to the area where the battery is.

That is how my battery conditioner is routed/connected.

The messages on the UK message boards are inconsistent if all cars have a live lighter. Some cars do, and others do not. In the US all lighters are live. If you want to use the type of charger that plugs into the lighter socket and your lighter is in fact live, then look at the bottom of the door seal. There is a half-moon cut-out for the wire, so you can close the door with the charger plugged in.

I have a motorcycle, for which a conditioner is essential, as they have smaller batteries, and my unit came with a connecting cable that you hard wire to the battery (complete with an inline fuse). This cable is terminated with a connector that mates with one on the end of the conditioner cable. With something like this, you could site the permanent cable somewhere accessible when the car is locked up, such as the slot between the bonnet and wipers as suggested, and simply open the bonnet feed cable, connect, close boonnet, lock car and Bob's your uncle!

Now that is EXACTLY how mine is connected[ ]

Doh, I've noticed that half moon before as I was wiping the seals and it never ocurred to me what it was for! Lot's of good suggestions here, thanks everyone.