cayenne battery
 

So

Wifes cayenne feels like its been sluggish at first start in morning.

Feels like its pulling hard to turn over.

Bring to local independent.

He tests battery and says its at 8.6 volts.

Says good idea to put in new battery. $300

Then says, by the way its likely that starter needs replacement also. $750

Does that make sense?

Did he put a load on the battery? Voltage doesn't really tell the whole picture. Could it be an alternator or grounding/cable issue? How old is the battery?

Updated Battery / Starter / Alternator Harness
Per Porsche's technical bulletin.

Issue: Battery discharged and/or will not charge properly. Voltage drop due to alternator-starter-battery harness damage at starter terminal. This issue is often mis-diagnosed as a bad battery, bad alternator, or bad starter, and these parts are often replaced in multiple repair attempts before the harness is determined to be the cause of the issue.

Before ordering or replacing other parts, have the car professionally inspected. Check the voltage drop between the alternator and battery. Bring the car to normal operating temperature. Turn on as many power consumers as possible (AC, headlights, radio, defroster, etc.). Use the same grounding point for the following voltage measurements:
- Measure the voltage at the "B+" terminal on the alternator.
- Measure the voltage at the battery positive terminal.

If there is a voltage drop of greater than 0.5 volts between the alternator and the battery, and all of the connection points are tight, check the harness terminal at starter. It is possible that the crimps on the starter terminal where the two cables are joined together incorrectly, causing an excessive voltage drop between the alternator and the battery. This voltage drop does not allow the battery to charge properly, and as a result, the battery will continually discharge until it will no longer start the vehicle. There may be no visible damage to the harness, and more measurements may be necessary to determine which cable or part of the cable is responsible for the voltage drop.Updated Battery / Starter / Alternator Harness:Suncoast Porsche Parts & Accessories

It is most likely just the battery. I had similar indications and replaced mine myself...pretty easy task as it is under the driver's seat...but if you don't want to do it, have the independent do it. Cost me about $200 for a battery at Autozone. Worked perfect for last 3 years.

Bulletin above is not for Cayenne.

Crap! My bad:)

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Sounds like an opportunistic mechanic. Do as Fint says, grab a battery at Autozone for a few hundred and DIY it. Porsches get really sluggish when cranking with a weak battery, and they sometimes develop weird gremlins as well.

Ha

I saw that same video on you tube.

He has some sort of machine that measures the battery under load and the starter.

Under load the battery drops to the 8.6

He says that he can't get a clear read on the starter because since the battery is low it throws of the amp reading that tells if the starter is working properly.

This car has been a gem.

I think a new battery will solve it.

It is probably 5 plus years old at least.

Im thinking he is pretty straight. He let me know that the front brakes are getting close to need replacement.

The brakes ill do. Easiest brake job ever. Fronts anyway.

Don't put it off either btw. For whatever reason, Porsche batteries like to go from passably marginal to DEAD, often overnight.

Roger that.

ill have the shop do the battery since its there.

To the OP, sounds like a load to me. Mechanic sees $$. My guess is that the battery needs to be replaced and the starter is fine. But I could be wrong.

Seems like these days, they all do that, except maybe for miatas. Most of the battery failures that I've had in the past 25 years have worked great, then maybe 1 or 2 slow starts, then completely dead. I think I've had 2 miata batteries in the past 10 years or so that gave me lots and lots of warning, but I'm guessing that may be because they are AGM batteries.

Why is the battery at Autozone $200? Last time I bought a battery, the top of the line stuff is maybe $90?

I start seeing Cayenne Turbos for $20k and less. Intriguing ...

G

My guess is under $200. Most of the vented batteries are around $150.

The price of lead is sky high. All batteries are expensive right now.

What a pain in the butt.

What happens if the battery is shorted or dead?

The last two batteries that died on my daily driver were fine one minute, and so dead the next even with a jumper cable on it it would not crank the starter. My radio would not even come on. I presume there is some workaround. It probable involves removing the seat entirely.

I can confirm this from experience!

What a weird place to put the battery!

I guess it keeps the center of gravity low.

IIRC, some running electronics won't work if given less than a 9.0V supply.

Basic stuff with a voltmeter:
Test disconnected(no radio/alarm/etc parasitic draw)
Test connected.
Pull the fuel pump fuse and test while cranking.
Start and test what the alternator is pushing at idle and 2500rpm.

More than 3-5 years old and it snows there? Replace.
I just replaced my Diehard mfted in 2006.

That and there is not a free inch anywhere else to put it. The turbocharged V8 literally fills the engine compartment.