Need a little advice here folks. My battery will not start my 08 C4S in 4 days of no use and is completely dead in 5 days. Had to do the fuse panel trick to get the hood open in order to get a charger on it. Charges up fine.
OK a bit of history. Brought the car to my local stealer on LI, who charged me $150 to tell me everything was good, Battery, ground, alternator, but said my recently aftermarket radio/Amp was causing the problem. Fine. I disconnect the the huge fuse from the radio to the battery when I was not using the car and figured all was ok. No such luck. I am out of ideas anybody out there have any ideas?

Just remembered I chased a similar problem years ago on my wife's Miata it turned out to be the factory alarm system. ????

 

Assuming no extraneous battery drain and also that this is the OEM battery, it may just be time for a new one. The OEM batteries are a well-documented problem area. I've had an OEM battery that seemed to be strong, slow start one day, charged overnight, started fine the next day and then failed the following day.

 

bad battery. time to replace. Mine had to be replaced after 1000 miles

 

Battery checks out fine. It is not OEM and as I got the car "pre owned" I do not know how old the battery is. Although it is a Duralast with a 7/12 sticker on the side. I'm stumped.

 

maybe not helpful, but IIRC my manual has a troubleshooting guide for battery drain.

 

I would get a second opinion on your battery. Is anything else not stock? These electrical systems are so interconnected that changing any one thing can cause gremlins. It does however sound like the battery is cooked. Many times when a battery is drained completely, it won't accept a full charge afterwards.

 

Sounds like a dead battery or maybe an alternator issue to me.

 

I know my local stealer said everything checks out, but could this be the the dreaded starter to alternator cable frying? It does have the classic symptoms. How do I check this?

 

Change your battery.... no matter what you are thinking or what people tell you. If your battery is 3 years old... It IS THE BATTERY you should replace FIRST before you spend any other money , time, effort, beer, cookies,, you get the idea :-)

 

Although I'm turned off by the whole "stealer" generalization embedded in the OP's forum personality, I agree with those who state the battery is just old. They have a limited life. Toward the end of my '08 C2S's battery life, I was charging it daily with the Porsche smart charger and it was never going to regain those lost cranking amps.

You have 2 choices, replace items when they die or replace on a average lifespan under preventative maintenance. I knew I was going to trade the car soon so I opted to not replace the battery. Perhaps I was simply fortunate I was able to preserve the battery long enough to make it to the car's final days (with me).

 

What he said! Replace the battery and be done with it!

 

Late to the party here, but did you leave the keys in the ignition? That will drain the battery in that time period.

 

3 year old battery should still be good.
I suspect it could be alternator? Or there any mods from previous owner like LED DRLs?

 

I'll bet that GuzziGreg already solved the problem that he wrote about on Nov 8th. Also, he wrote that his car doesn't have the original battery. He has a Duralast with a 7/12 sticker on it. We shouldn't assume that his battery was 3 years old.

.

 

Well if he did maybe he should also share how. We should share in good times and bad.