Battery charged - electronic issue

Hi all, I left my battery go flat over the winter period,I've now charged the battery up and powered the car on. My car alarm kept going off and I couldn't stop it so I spoke to porsche and they said to disconnect the car alarm which I have done. Now I seem to have all sorts of electric issues, I have no ABS,PSM, indicator lights on the dashboard with also my spoiler failure (as its currently set up). The car felt really sluggish and quite noisy, I'm not sure thats due to it not being used and now having the correct systems on. I have 14Volts on the battery whilst the engine is on, but I have no idea why im lacking all this electric faults. any ideas?

Your battery may be toast after having gone flat for so long; I would highly recommend getting it tested asap. A failing or dead battery will throw all sorts of seemingly unrelated faults on these cars; they are very sensitive to battery health.

I would also highly recommend using a battery maintainer from someone like CTEK if your car will be sitting idle for any length of time. They keep the battery charged while you're not driving it but will not over-charge it like a trickle charger will. (Which would also ruin your battery if left on long enough) You can leave the maintainer hooked up indefinitely and expect it to fire up first time when you go to start you car.

As @tomerie said, your battery is likely damaged. You cannot let lead-acid batteries go very low, because that damages them and requires replacement. Voltage during engine running is not a good measure of battery health at all... when the engine is off for a few hours, you can read the voltage and see what the SOC (state of charge) is at that point, but I don't think your battery is going to come back from being dead. If you're in a cold region, that further damages the battery when dead, too. Just replace it. Sometimes, when the battery dies, the various computers in the car lose their settings. This can require reprogramming them. The dealer can do this, because generally it requires PIWIS.

Thanks all, I figured it would be battery related ive got one on order so will replace once its arrived and hopefully will clear me of any errors !

Toasted battery …. Buy a Ctek and your troubles With that won’t happen again

Yes, when the battery dies, the ECU loses connection to multiple devices so it thinks they are lost/broken. Scan the car and you might see codes like ABS sensor Voltage out of Range, etc. That is why when you change batteries, you want to keep current to the car on modern cars. A lot of people here recommend the very same trickle charger from CTEK , the MXS 5.0 to keep your battery happy. This is basically the same charger Porsche sells with a Porsche label on it, but I have posted that while this is good, the one that is better is the CTEK Multi US 7002 because it does everything the 5.0 does PLUS it has a Supply Mode. The supply mode allows you to connect this charger and supply current to the car while you swap batteries so you don't get all of these issues. So if you get a trickle charger, for a little more money the 7002 has the supply mode that helps you change the battery and keep current on the car. I personally would use supply mode with the alligator clips on the body instead of lighter port but that's just because I am extra careful, but it's probably ok. The supply mode is NOT to jump start your car, just to keep enough current to keep all the sensors happy while you swap. So, you need to replace your battery with the exact same type. If it's lead acid, then lead acid. If it's AGM , then use AGM . If you want to go from lead acid to AGM , I am not sure what year on you have to register the battery with the car, but if you use the same battery type and MAH rating you should be fine. Once you have a fresh battery , clear all the codes from when the battery was dead and the car should be able to find all the sensors and keep everything happy.

This above, missed it the first time.... I would try just resetting codes myself, then if that doesn't work try dealer.

There isn’t any need to order anything. There’s nothing special about the battery in these cars. It’s just an off the shelf battery that you can buy anywhere for about $200 or less. Don't fall for the Porsche $500-600 battery rip off, as a comparable Walmart battery is exactly the same since all automotive batteries are manufactured in one of only about 3 to 4 worldwide factories. They are the OEM for just about everything and every brand because the auto makers do not make batteries themselves, and there is nothing different but the sticker on them

That's unnecessary with a 986 or 987. These are pre-registration/adaptive charging. They use a simple voltage regulator that responds to temperature and battery resistance to determine the charge rate used. There is no coding of this needed or even possible. If it has a lead-acid battery I'd suggest for the few more $$ it will cost to go with an AGM battery. Aside from no spillage issues, it tends to be higher current rating for the same physical size, and is usually longer lasting. ANY battery installed in a Porsche should have an external vent. Make sure the battery you buy comes with the vent kit (usually an small elbow and some tubing) and use it.