moyamin

Hello all, The battery of my 2008 911 Carrera 4S with about 40K miles died after sitting in the garage given our NE winter. Now I can't get it to jumpstart with even hooking it up to our bad boy Dodge Ram battery. I also tried two different models of 12V battery jump starter that I have. Neither worked. The engine cranks very slowly in all cases. Am I missing something?

Also, what kind of new battery do you recommend.

Thank You.

Wayne Smith

What is the voltage at the battery during cranking? Are you leaving the cables attached for a few minutes before trying to start? Is the truck running and at or above 2000 rpm when you are trying to start the 997?

moyamin

I am not sure how to read the voltage on 911 dashboard, but the cables were attached for quite a while and I did rev the ram a couple of times before trying.

Wayne Smith

You'll need a voltmeter held at the battery posts to read the voltage. Meters are cheap to purchase.

Connections are never good (some better than others but never good). I suspect the cables you are using are minimally connected and your dead battery is pulling the voltage down. But without knowing the voltage there is little advice to be given.

WPOZZZ

How old is the battery, and was it hooked up to a maintainer during the winter?

French Fries

Are you jumping from the battery and not the fusebox? Which jump starters do you have? From my experience lithium ones aren't strong enough for the 997 battery, I've tried all the higher rated NOCO models. You can connect the truck battery and 2 jumpers at the same time - try that to see if it'll get the job done before you call someone or try more products. If that fails get two jumper cables and call an UberXL, that should do the trick.

slicky rick

Replace that battery your done

cdk4219

Yes replace the battery, or charge it back to see if it will hold a charge. The alternator isn’t a battery charger and it really doesn’t like to do those duties

Kitc2246

Many jumper cables can't carry the amps needed to immediately jump start a dead battery. Same for jump packs. Leaving it connected to the battery for a few minutes hopefully charges the dead battery to a point that the jumper and dead battery will start the car. Obviously replacing the battery should solve the problem. You can try to charge the battery over night with a battery charger. A CTEK or equivalent battery maintainer will not normally charge a completely dead battery. If you DIY you can remove the battery and have it charged and load tested. If its more than five years old I'd just replace AND get a CTEK or equivalent. If you don't have AAA or equivalent check or call your car insurance to see if a jump is covered. I have AAA and towing on my insurance.

frybear

I use a jump pack, starts up right away with that vs. trying to jump from another car...nada.

ADias

That's the way to go.

celo626

Jumping in here - I have a '13 C4S and it is typically on a trickle charger (Porsche). Circumstances changed and I had to park it at work for a few days. In that time, I drove to Porsche for my 40K service. I drove it the 8 or so miles back afterwards. Took a week off during the Fourth, and came back and car will not start. Have tried leaving it on the trickle charger for 4 days, and tried a jump pack as well as a jump from a Silverado. Nothing seems to work. Voltage meter reads 12.2 or so at the battery. I thought it should start with that much juice, but I guess not. Anything else to try before I buy a new battery? Really I just need to jailbreak my car from my work & get it home. I have received the "sockets disconnected" error message, but now I get messages about heated steering wheel (which I don't have) and other oddities. Thanks in advance.

moyamin

I hope others can suggest something else, but a new battery worked for me. My airbag light stayed lit after the start, which I read is normal on 08. It needs a specific device to turn it off.

ADias

If after a week (when the car consumed a mere 7Ah) your battery did not start the car, it means the battery is dead or heavily sulfated. Change the battery.

celo626

so, installed a new battery and still no dice. It made slightly more of an effort to start though, but my voltage is still not exceeding 12.2. What’s next??