I had the same exact issue with an AntiGravity 60ah on my 991.2 C4S with RWS. AG took the battery back, but they had no advice about how to resolve the issue at the time, so they gave me a refund. It was frustrating because it is a slick piece of kit and the potential weight savings is amazing. Tempted to try another one again now.

 

I installed the 60 AH AntiGravity battery over two years ago not and it has been flawless. I normally use a LI specific battery maintainer when parked in the garage and during the 6 months of 'winter' storage in this climate. Took a 5 K miles trip last Summer and no problems what so ever. Great new technology and , while expensive, I consider it on par with the other technology of our German machines!

 

No issues with my AH40. Very happy with the weight savings over stock and I have tons of CCA’s, never an issue.

 

Sorry, but I’m not impressed by all the “no issues” comments. The battery costs $3800!!!. There better not be any issues.

I’m firmly in the “replace every few years for $200” camp.

DaveGee

 

The Antigravity battery referenced in the title is $660-$950. The references to a $3800 battery are what BMW charged for the OEM Lithium battery that came in the M3.

 

The M3 has a LiPo and standard lead-acid (or more likely AGM) battery, no? I recall my buddy at the dealership talking about how horrid that system was. $2500 cost for the batteries if they got discharged too much. Poor BMS and all that. I've got one sitting in my garage I was meaning to rebuild and sell.

You can code the 991 to have a lithium battery alternator profile? Astounding, I had no idea the BMS in the 991 was capable of this. I saw no such setting last time I perused, I'll have to check again.

That said, the BMS in the AG battery is designed to not require such changes to your vehicle, and in fact protects itself from over and under charging, per AG themselves who openly state they have tested this on many vehicles and basically never saw over 15v, which means that your alternator and your old 1997 Schumacher battery charger should be A-OK to charge. That said, they also go on to say that AGMs shouldn't be charged over 15v which is objectively incorrect, and that alternators "sense air temperature" to raise voltages, so what's the real truth here?

 

Correct. The AG battery is around $750. To put it into perspective.. Porsche is charging $11,000 for a lightweight package that shaves 60lbs off of the cars weight. You can shave 40lbs off by just changing the battery. Want to shave another 25lbs?... change the wheels to lightweight. Want to shave another 25lbs? Change the exhaust to titanium. Almost 100lbs saved and still less than Porsche charges...

I went with the highest amp AG battery because I had an aftermarket stereo, custom installed radar and front and rear dash cams, so my parasitic draw even when the car was parked in my garage was high. With the AG battery I had no errors or faults, no need to recode anything and the battery cranks like a MF...

 

That was the direction I went with HREs and an Akrapovic exhaust, but it was frustrating that the AG battery was an issue that AG did not solve for me, except with a refund. 2 trips to the dealer to address the RAS warning lights was enough for me. I asked the dealer if there was a Lithium BMS setting for the car but they feigned ignorance, so it was just easier to put the OEM battery back into the car. With that said, I will discuss coding the car for a Lithium battery with an indy Porsche shop. I would love to shave another 35lbs off the front end being a C4S. Hoping it livens up the steering feel a bit more.

 

You’ve got to do what works. electricity can be bizarre and I claim no mastery over it. I’m doing something different than most. I only top charge and disconnect. All lithium equipped vehicles just will not take any charge regardless of the charger used. It’s more of a manual operation for me monitoring input voltage over time and voltage cutoff either by me manually or automatic by the charger. After all you are only adding dc at a certain amp input. All chargers simply add virtually nothing in my situations before reaching max volts. All lithium equipped just remain high volts. So I’m in a different camp from those leaving chargers hooked up for extended periods. Chris at anti-gravity said there was no need to code for lithium however next maintenance I’ll have them do it anyway.

 

My experience was more a case of the battery BMS and car BMS not working well together. The car itself was over-charging the battery causing a huge spike in voltage which caused the battery BMS to cut the voltage dramatically for a second to compensate, but that was triggering the RAS system control module fault. Dealership was making claims that the battery voltage spike could permanently damage the RAS control module, so a quick assessment of the costs of covering a new one (likely not covered by warranty), made me realize it was probably better to just send the AG back and try again in the future. With that said, I will look into the re-coding of the car to accept a Lithium battery.

 

Can I borrow someone's credit card?

 

Ouch. Seems like a risky game to play to save a few pounds on the wrong side of the car, to me.

 

Not to minimize the problems that the OP had, most folks pop these in and they just work fine. I'd buy one in a heartbeat.

 

To each their own. I'm nowhere near a good enough (or aggressive enough) driver to notice 40 pounds missing from the cowl of my car, and it's just not worth the headache of "ah crap, did I plug in my car" every four days. I didn't buy a Nissan Leaf for a reason, damnit!

 

HAHA! I totally understand.

I'm the guy who is on his second Tesla though. ;-)