Numerous List Members have reported flat betteries after only a few daysout of use. The 964 seems to be prone to small current drains - immobilisers, glove compartments, alarms, all have been blamed.

Solution 1 is a starter battery - success came however, when for the first time I used the, Red Flash 8 Ultra Light Portable Power Pack. which I purchased a couple of months ago and keep in the boot. After in the past having to push the car out of the garage, manoeuvring the two vehicles together before fitting on jump leads. This time I was able to connect the Power Pack to the battery, switch on and away. It was worth every penny it cost me. Ken C

Solution 2 is a Battery Conditioner - I use a Carcoon charger which cuts out when fully charged, and cuts back in if necessary when the voltage reaches a lower level. No more flat betteries - Rob F

I found my car with a flat battery only 24 hours after having driven it 40 miles or so. Camtune (in Godalming) diagnosed the problem as being the sampler fan (apparently it is used by the climate control to obtain the air temperature in the cabin). It was running on after the car had been switched off. They disabled it somehow and I haven't had any more flat batteries. However, I also don't have climate control although the heating still responds to the temperature knob - Tom D

Flat battery problems & a Tiptronic problem:- I kept getting a flat battery & although I could use jump leads from my wifes or neighbours car (assuming they were around when I needed them), I finally decided to bite the bullet and bought a Priority Start Battery Protector from Mathew at Type 911 in Beckenham.
This clever piece of kit continuously monitors the voltage (when the ignition is off) and when it drops below 12 volts, isolates the battery. Then when it reads a requirement for power again; such as when you put the sidelights on; it automatically reconnects the battery.
Installing it was a 15 minute breeze with the easy to understand instructions provided and although it's a tight squeeze, I found the best position for the unit was strapping it onto the positive battery terminal rather than round the complete battery as suggested in the instructions. The Pain is that in the isolated mode, the clock & radio settings are lost (big deal!). The alarm is also disabled (unless you have a battery back-up system) but will automatically re-arm when the system reconnects. The Gain speaks for itself. The battery will always have a full 12 volts available for starting even after a few weeks/months!!
If the system has isolated the battery; the central locking won't work, & the alarm LED will not be flashing. NO PROBLEM. Open the door with the key, turn on the sidelights and you'll hear a whirring sound under the bonnet as the unit reconnects itself . Press the remote central locking/alarm button on your key to turn off the alarm and away you go!! It might seem expensive at just under £100 but what price peace of mind? - Dave B

Solar powered battery charger was from Innovations (£25) & plugs into the cig lighter (which needs to be rewired to stay live with the ignition off). Works very well & Ken also has a different make which he's happy with.