Cayman S Battery

Buddy · May 12, 2011

Engine cranking has been slow for a few weeks and seems to be getting worse, so last time I was near to the OPC I called in and checked on the price of a new 80ah battery, £164 over the counter including PCGB discount.

Probably the same price at any OPC but I'm rather locked into a genuine Porsche Battery since the extended warranty demands it.

My son had a none Porsche battery on his Boxster S and was told they would not extend his warranty even though he'd bought the car with battery from a Porsche OPC.

I've heard that if you have a failed battery and call Porsche Assist they take the car to the dealer and then you get a bill for around £240.

As there are other things which would be covered by warranty I checked voltage standing and charging and found 12.1 volts about an hour after switch off but running I have 15.3 volts showing some overcharging.

So, no alternative, I'll just have to cough up, I'm just a bit dubious of a battery which probably won't last better than one half the price. I'm seeing on the net that the Porsche Branded Moll batteries are not considered the quality for the money.

Peter Anthony · May 14, 2011

I had a replacement battery on 28/09/2009, Â£171 incl vat on my Cayman S. Any fitting charge is lost in the additional Â£116 incl vat costs of checking and testing on top! It happened when my son was using the car and we had borrowed his motor to go on holiday. Battery went flat at the start of this month and it went into the OPC. They tested and replaced FOC and returned the car home washed. Seems the parts have a warranty of two years and you must have done a 1,000 miles on it. Battery had a failed cell. What do we know of other manufacturers such as BMW? I also have a 330D and I believe when they sell a used car it has to be at full BMW spec so maybe non BMW parts would invalidate a warranty.

Buddy · May 14, 2011

Hi Peter, I've never known it where a warranty could be void for an alternative brand of battery which can be considered a wear & tear item, plus of course is a Porsche battery always available? They probably have a greater cause to change them in winter or when cars come out of storage in spring, so best to phone before going to buy a replacement. It was certainly annoying when my son was told he needed to replace a battery effectively bought from Porsche because it was a different brand! I usually use my car through the whole year but last summer bought an old MX5 for commuting rather than be using the Cayman in heavy traffic doing 130 miles a day round trip from home to a job I was then working on. Well, the job went on from July to March and I was usually using the Cayman at weekends and the occasional odd day to work and no doubt the lack of use has a great deal to do with the battery not holding charge as well as previously but that only became apparent when I started to use it again regularly and even after a 20 mile run it will crank slowly. Maybe if I'd used one of the CTEK trickle chargers I've read about it would still be ok. When charged it reaches full charge overnight giving 12.6v but this falls to 12.2v over 24 hours, maybe a trickle charger would do the trick even now but previously it could stand for a couple of weeks and be ok so I do need to replace it pretty soon but I'm considering a CTEK or similar unit to help preserve the replacement. What experiences of these units have others had?

DarrenG · May 14, 2011

Hi - I've used the CTEK charger for just over a year and its been a case of so far so good...I garage mine for weeks at a time and leave the charger connected at all times. I read somewhere that it slightly discharges then re-charges the battery for optimum efficiency and basically the LED on the charger alternates between orange(charging) and green(fully charged). Its easy enough to fit and the lead from charger unit to the battery is quite long....hope it helps. Rgds.

Buddy · May 15, 2011

Went out in the Cayman last night and called in for fuel, battery had been charged and lights etc were all bright so no shortage of power. Switched everything off while I filled up and paid. Came to start up and it took a couple of tries of the key, second crank was pretty slow so I thought D**n Battery! Returned home about 20 miles later and dropped the voltmeter across the battery 12.6 volts so good state of charge, this dropped to 12.45 later so not bad. Checked it this morning, still 12.4 so it begins to look like a possible starter. Went to the local accessory shop and got one of those LED indicators for testing of the battery, alternator & starter. Connected to the battery and started the engine, first indication was faulty alternator, overcharging. Electrolyte levels are ok in all cells. Put the battery on charge to ensure fully charged battery and battery health looks good but half charged, tomorrow I'll try the Alternator unloaded and loaded, I just can't understand how a seemingly overcharging Alternator can cause slow cranking. Which has usually been after I've been out and when I come to restart after leaving it parked a few minutes on the road while I'm getting the other cars out of the way to put the Cayman in the Garage. It's only recently this has been happening and still raises a question on the starter.

Buddy · May 16, 2011

Had a Porsche trained mechanic friend take a look and he said the Alternator is compensating for a weak battery, all cells just made the "fair" band on his hygrometer and as it was freshly charged it indicated weak battery but at least all six are giving enough effort to do their job, he also checked the alternator and said it was good and even coped well under load supplying a consistent 14.8 to 14.9v . He said that when the battery was discharged the alternators can go to overcharge to boost the battery. One other thing he warned of is that on the 987 & 997s he has had a couple which had a problem with the lead from the alternator to the starter motor, causing slow cranking he said that they had overheated and needed to be replaced some main dealers don't know of this and start changing Starters, Alternators etc, the lead apparently is about Â£82 and it takes about 4 hours to change it. Just about to call the OPC for a new battery.

DarrenG · May 17, 2011

Many thanks for the update and the tech feedback, much apprecaited. Dont forget the PCGB discount on the new battery.....Rgds.

Buddy · May 17, 2011

Charged the new battery today and fitted it this evening, what a difference. I make more than my club fee in discounts each year, daft not to be a member isn't it? Not to mention all of the other advantages of associating with other Porsche nuts.

Buddy · Jul 6, 2011

Bought a Charge-o-Mat on Ebay which arrived today, it was unused and for only Â£38 should be money well spent. For the past 4-5 days I have only done one short return trip and got the car out of the garage to do some work in there then put it back hours later, Charger has now been on for about an hour and is still indicating charging. Useful not having to disconnect the battery and to plug into the lighter socket, as the lead goes through the window and across the driver's seat it's unlikely to be forgotten. Like lot's of others I do occasionally need to leave the car untended for weeks at a time so it will come into it's own then. Although it's unlikely at present for me to not use the car for a long period I'll use it over the next few weeks and post my findings.

richardrimmer · Jul 8, 2011

Just had to replace the battery on our 2007 Cayman S as it let us down recently. The car has a tracker fitted which doesn't seem to help with draining the power when the car isn't used for a couple of weeks. Unfortunately the car isn't garaged so it's not so easy to use my C-Tek charger that I have the RS connected to when it's parked up. Club discount doesn't make the battery seem very good value still at nearly Â£170 but as previously mentioned, Porsche extended warranties and non-genuine parts don't mix! We even had them trying to get out of fixing a fault because non genuine bulbs had been fitted at some point (not by us).

Nick_USA · Jul 8, 2011

ORIGINAL: richardrimmer Just had to replace the battery on our 2007 Cayman S as it let us down recently. The car has a tracker fitted which doesn't seem to help with draining the power when the car isn't used for a couple of weeks. Unfortunately the car isn't garaged so it's not so easy to use my C-Tek charger that I have the RS connected to when it's parked up. Club discount doesn't make the battery seem very good value still at nearly Â£170 but as previously mentioned, Porsche extended warranties and non-genuine parts don't mix! We even had them trying to get out of fixing a fault because non genuine bulbs had been fitted at some point (not by us).

Solar powered charger could be an option for you then.