An unexpected Porsche headache this morning, as the Cayenne left me stranded at the LPG pump with a flat battery. It had started OK on quite a cold morning and I’d driven the fifteen miles or so to the station with dipped headlamps on due to fog. I left the sidelights on with the engine off while I filled up but, when I was finished, the Big Pig wouldn’t crank enough to start the engine. Five minutes with sidelights on had drained whatever voltage was left in the battery.
I always carry jump leads, so I borrowed the working car of a friendly passer-by and got a jump start: it fired up straight away. I drove around the corner to the local Euro Car Parts and bought a new Bosch S4 019 battery to replace the non-Bosch item I had fitted just over a year ago: £104.40 including VAT, which was not too bad for a big battery with four-year guarantee.
The old battery had been a bit of a worry since Christmas, when I had to jump start the car a couple of times after it had been standing for a few weeks. Although my 2004 Porsche Cayenne S has now done 154,000 miles and is still on its original water-cooled alternator, diagnostics showed no problem with the alternator and all the wiring looked OK, so it had to be a battery problem.
When I first bought the car, it had a great Bosch S5 Silver battery fitted. I had a few things play up a bit including the starter and forum wisdom suggested the battery was at fault. Euro Car Parts could supply a Lion battery with slightly more amp hours (100Ah/800 CCA) than a new Bosch S4 (95Ah/800 CCA) and a three-year guarantee, so I bought one and fitted it. Of course, it made little or no difference, but I left it in there. I’m sure I still have the old Bosch S5 battery somewhere, which would no doubt still work perfectly but anyway, the deed is done.
Today was a busy day for the Cayenne trailering 911s up and down the country. It behaved perfectly all day after I had changed the batteries over, so I am hoping this issue is now resolved. It feels better to have a Bosch part back on the car – Porsches never seem to work right with anything else. I’ll claim on the three-year guarantee for the dud one so it should all work out.
How to change/replace your Porsche Cayenne Battery
- M10 multispline 3/8 socket & ratchet
- 10mm 3/8 socket
- 10mm spanner
Most Porsche Cayenne 955 (Gen 1) models have a single large battery under the left front seat: that is the passenger seat on a right-hand drive car. The seat base lifts up on a pair of rear-mounted hinges to allow access to the battery box. The multispline M10 bolts which hold the front of the seat frame down are under the two plastic covers in front of the seat: these just clip off to reveal the bolt heads.
Undo the bolts and tilt the seat up: hold it up out of the way with a strap to the grab handle if you’re worried. Now you can see the battery cover, which has four clips, one in each corner: undo those and lift the cover off. Your 10mm spanner will undo the terminals (remove earth first), and the 10mm socket will undo the front corner bracket, and the big side clamp holding the battery in place. If you’re worried about losing your radio settings etc, connect a battery charger to the terminals before you unhook them.
Once the two clamps are off and the terminals have been detached and secured out of the way, disconnect the small battery vent hose and get the old battery out of there. It is worth cleaning any dirt and dust out of the battery tray before sliding the new battery in.
A bit of petroleum jelly on the terminals before connection is an old-school habit, but not too important in these days of sealed batteries that do not give off corrosive vapours when charging. Then reconnect everything, put the lid down and bolt the seat back to the floor: use a bit of blue Loctite on the seat bolts. Have a cup of tea & a decent biscuit – you just saved yourself a few quid by not going to a dealer.