DaveGee

Fair enough - thanks for the clarification.

DaveGee

fsmich

Please check and report back,lol. My indy was doing a brake flush, and did not charge me for the piwis "coding". Maybe he was pulling my leg and did some other magic to keep it from charging at 15+volts.

Here's the rest of the AG quote.
"we did not forcast some Porsches going into the 15.4 and as high as 15.7v range during the colder temps. And the fact is it appears only SOME of the Cars go into this range. So when they do go above 15.2v at any time our battery knocks down the voltage which means our batteries voltages will flutter when the protections are kicking in"

AG recommends a lithium charger for their lithium batteries. You should buy one and try to return it after telling them you used your Schumacher to charge it.

My 40ah AG has been flawless for 3 years. I asked for the piwis coding because I did not like seeing 15v on the car's gauge.
The 40lbs it saves is good for about .3 secs on a 2min road course, which is why I bought it . It was by far the cheapest weight savings mod I've done. But I would but it again for the way it starts the car alone. It rip starts the engine!

polobai

I have the 40ah antigravity unit for almost 3 year now with no issues. My voltage stays around 13.7-13.8 while running and I think the voltage spike has something to do with cold weather (I am in Florida and don’t run into this much). I don’t plug it in-and the car sits for weeks at a time once in a while. I only had to plug in the lithium charger when I was doing my meth install and had the car down for 5 weeks or so. I also have their battery on my motorcycle that gets started twice per year and it starts up every time. Also over three years old.

Porsche_nuts

5 lbs versus 50 lbs may be worth the price just to save yourselves from back pain and from going to the doctor for muscle relaxers.

mc3456

I think you are accidentally conflating two different things (battery size vs type). Yes, some people are choosing tiny race car size Lithium batteries, and they don't hold a charge as long the larger OEM battery, but if you get the 40 or 60 ah versions, they do not need to be plugged in regularly to charge them. The larger the battery, the longer it can sit unused, just like a regular OEM AGM battery. The benefit of the AG is that they are 35-40lbs lighter, plus have the emergency reserve feature built-in. The vast majority of weight savings comes from just switching from OEM to a Lithium battery, regardless of size. The weight difference between the largest Lithium battery and smallest version is minimal, as in 3-5lbs.

The bigger issue is that depending on which 911 you have (often the ones with RAS) seems to be a charging system conflict resulting in some unnerving warning lights. Contrary to a recent post, cold weather has nothing to do with overcharging while installed in the car. My AG issues primarily happened during Summer-like temps. The car trying to charge the battery as if it is a different type is causing the issue. The battery is actually awesome, but AG did not set reasonable expectations that the conflict could occur and they unintentionally misled people that the batteries were plug and play for ALL cars. With that said, people have learned that adjusting the car's expectation about the type of battery may prevent the voltage spike.

Attached are pics of what the voltage spike looks like when tripping the dashboard warning lights to appear. Clearly a conflict with the car’s own BMS fighting the AG battery's internal BMS. Car attempts to over-charge the battery, thereby tripping warning lights, and then the battery's internal BMS cutting power causing a vicious circle that does not resolve itself on its own. Clearly, some 911s are capable of being programmed for Lithium batteries as they are offered from the factory on GT3 RS cars.

Zylinderkopfdichtung

Weighing in with my experience: I’ve had the 40Ah Antigravity battery in my Carrera T with RAS for a year. I’ve driven ~5500 miles on this battery, and tracked in half a dozen times. It has seen freezing temperatures through 90F+.

I’ve never had a RAS or other fault. I did not reprogram the car’s BMS though I have an iCarsoft with the capability. The battery has been plug and play for me.

I do leave it attached to a CTEK Lithium charger when not is use.

mc3456

Wondering if the year of the car makes any difference with the charging software on the car. What year is your 911T? My C4S is a MY2017. Clearly, there is some sort of solution to the issue for ALL 911 models, because it is not like a customer is to blame for just installing the battery, since some cause the warning lights and others don't. Either Porsche updated software along the way, or perhaps are using RAS Control units from different suppliers or something. Either way, the more people share details, the sooner the issue will be figured out.

polobai

Also to add mine is a 2018 with RAS and no programming for lithium battery.

Al.Fresco

Antigravity changed their BMS toward the end of 2019 so that it would not trip on higher charging rates that some 911s were throwing at it, previously causing the battery to protect itself which in turn caused the error codes from the car.

Antigravity

Antigravity Batteries here... I will try to anwer many of the questions here but just as important I will try to clarify many things since three is quite a bit of MIS-INFORMATION in this post. I am also going to say I will answer the questions and it will be facts and the truth based on 12 years in business of developing Lithium products for Consumers, Weekend Warriors as well as being in World Championship Vehicles in Cars,Trucks and Motorcycles and other Powersports including Drag Racing, Boat Racing and most any Motorsport that uses Batteries. Just want to make sure you guys know I"m not going to say anything that is not a fact, and that we do have the experiance and expertise that you can trust what I will say.

To the original Poster, thanks for going with Antigravity Batteries we appreciate it.... but, while the ATX20HD is a monster of a little Battery, and it can/may work fine in your vehicle (provided you maintain it and keep it charged), it is actually a very low capacity for a Lithium Battery in a 991 Porsche, and we officially consider it too low of a Capacity for a Modern Porsche being Porsches are especially sensative to Voltage and want alot of overhead in battery Capacity, called Amp Hours. The ATX20HD that you show is used quite a bit in the Performance/Race Car enthusiast crowds in Suburus, Hondas , Mustangs and the TUNER CAR Market, Race Car Market but those are Cars dedicated more to Track and Race use primarily and a Street driven Porsche is ultra-sensative to voltage issues and even being mildly over-discharge since they have a bit more in electronics going on in them compared to a Subaru WRX or Ford Mustang. Also the guys usually going to the ultra small Lithium Battery are hard-core enthusiasts who spend alot of time with their Car, making sure the battery is always charged and completely understand this. You might be one of those people and that is great, BUT the average consumer is not so we would never recommend the ATX20HD because it is NOT really an adequate solution, nor considered a direct repalcement battery. It may have problems if not taken care to a higher degree of and one of our warranty issues is says... "you must use the correct size battery for your Vehicle". You have to use the right tool for your job. It cannot be expected that a Battery with half the Capacity will work the same and last as long as the proper recommended product. This is not to upsell anyone, this is just plain facts. this battery was intended for Race vehicles and Powersports Vehicle like Motorcycles, UTVs and Racing Cars that just need the start and that don't need the extra capacity necessary for a Street Driven vehicle.

With that being said.... we'd love to keep in contact with you and see how its going for you since you taking this route. We just don't want others assuming its OK becuase typically a Car owner is not so into watching a battery so closesly, they want to just drop it in and forget about it.

Last, there are also additional stresses on a very small battery because it is working harder to turn over the motor than a bigger battery would, it is getting charged and discharged more often (called a cycle), so it actually sees much more use than a large battery since a larger battery doesn't even flinch to start a Car even if over-discharged a little. Also a smaller battery cannot alway accept a higher amp charge rate from the Car if that were to happen. So again we just don't want anyone going this route. Usually the smallest we recommend for a Racing Porsche is out ATX30HD... which is a 24 Amp Hour Battery also in a very compact format... but that is still 9 amp Hours More than the ATX20HD shown above.

We are a very conservative company and want the Customer to be excited and happy with their purchase.... so when a person goes with this small of a Battery we get scared because we don't want the Customer to be unhappy or report the battery as not being adequate. So just make sure to reach out to use if you have any questions about the size battery you can use for your application. We'd be glad to answer.

I'll follow up with answering some of the other questions above, and correct some of the mis-information I saw posted in some other posts so that I can clarify the facts about lithium for those interested.

Antigravity

- ICU99 You DO need a Lithium Charger specifically for charging a Lithium Battery and they range from $50 dollars to $120 dollars in general. You would want to get a Lithium Specific charger with a 4 amp minimum and also a decent name brand like CTEK or Tecmate/Optimate because they make good chargers with a good charging profile you can trust. Please see my response below to Asselus to understand why you need a specific Charger.

- BlackCheetah... Your information is relatively accurate.... BUT in a 991 and depending on the level of accessories 1 amp will not be enough to over come the Parastic Drain of the Car if the car has any other electronics like a Camera, and or Radar Detector, or even a USB Charger in the Cig Lighter Port... The issues that comes up is the 1 amp of output from the Charger will taken by parastic draw or potentially other Accessories like the Radar detector. This will allow for a very small amount to be left to charge the battery itself and the re-charge will be very slow. So we recommend to everyone that you do not buy any charger below a 4 Amp LITHIUM SPECIFIC Charger to maintain your Car Batteries.


Asellus there is no "Snake Oil" here. Here are the facts, a Stand Alone Charger that you use to charge your Lead/Acid battery, like a Battery Tender or CTEK Charger , does not operate like a Alternator in the car when charging. These modern Lead or Lithium stand alone chargers have Charging profiles that are developed for the chemical type of the battery they are charging. For example a LEAD/ACID Charger will often have charging profiles that actually helps eleminate Sulfate that can develope on the lead/acid battery plates by spiking the voltage to the Lead battery which removes sulfate from the Lead/Acid Battery. A Lithium Battery cannot and will never develop sulfation because it is a completely different chemical make-up so spikeing higher voltage to a Lithium Battery serves no purpose and can damage the battery. Last a Alternator does not have a charging profile that has these voltage spikes to remove sulfation like a stand alone Lead Acid charger does. An Alternator simply uses a constant current/constant voltage type of charging that actually works great for Lead or Lithium. Also, a Lithium Battery also does not need the absorbtion phase of charging like a lead/Acid battery needs so it can charge much faster. So there is a different charging profiles for a stand alone Lithium Charger vs the Lead Acid charger so that is why there are specific chargers for specific battery chemistries.

Last you brought up the Battery Management System of a Lithium Battery should have a system to make it compatible with a Lead/Acid Battery Charger.... this is not accurate. While the protections of a Lithium Battery's Battery management system may protect the battery from voltage spikes from a Lead/Acid charger in Sullfate mode, that is not a cure for not using the proper tool for the job. There are other factors in a Lithium Chargers profile that it performs to make sure the Lithium Battery is taking a charge properly and a Lead/Acid Charger won't have those functions. So simply just get the correct specific Charger for maintenance of your battery. If you drive every few weeks you may never even need the charger on a Lithium Battery... but best to have one, and just use the proper one.

blackcheetah

Thx you for your input it is very appreciate so you say my ATX20HD that has 900crank amp but only 15amp capacity? I tough it was a 30 amp battery like shown behind the battery box?
I will report back in 1month about my battery
If i like it or not ,for now everything is fine Car start with radio and light on i know it would not last long without alternator

Antigravity

YOur welcome and we just want to make sure you are happy with it... you said you had it in a 993 also, but the 991 has more draw and electronics and more sensative to low voltage and will throw flag like Steering flags when low on voltage. so I was a little nervous. But just keep trying it for a while and let us at Antigravity know how its going. YOu can email me from my signature.

So you can understand better there are two things in regards of what to look at with any Battery... but especially if you are going smaller. They are called "Amp Hours" and "Cranking Amps" They are two completely different measurments for a Battery's "Capacity" vs a Battery's "Power"

1- The" Amp Hours" is MUCH more important than the "Cranking Amps" Amp Hours are the Capacity you get with the Battery. Its a way to measure how much energy the Battery can store. To put it in simpler terms Amp Hours its HOW BIG the Battery in side the Case is. For example if you consider having a Cup of Water and compare that to a Gallon of Water, the Capacity is how much water you have available to use. The Pint is a much smaller capacity, and can quench your thirst and work fine for a little while, but you will run out if your drinking more than a little bit. Whereas the Gallon is better because you have a bigger capacity that can last much longer and you don't have to worry about refilling it so much compared to having just a Cup of water. So higher capcity means a bigger battery, with ability to store more energy so you can have more energy to power the accessories on your car longer when the car isn't running, you car can be in storage longer, the battery won't drain as fast, and if you have a bigger battery in the first place then you will alway have more POWER available for starting as well.

2- "Cranking Amps" are the ability of the Battery to provide a quick burst of Current which is basically the Power to turn over a Car Motor. For Lithium this high output discharge is very easy to do and we have incredibly tiny batteries that weigh only 1.5 lbs that can easily turn over a Porsche Motor and get it started just fine, but even though that tiny battery can start the Car it will not have enough "Amp Hour Capacity" to run the lights more than 10 minutes or less because it is so tiny and has no "capacity" (Amp Hours). So it basically useless for a Car because it will go dead so quick. So yes your ATX20 Battery can put out a "Pulse Discharge" or high Cranking Amp number of 900 Amps which is more than enough to start any Car on the Road.... but it will not have the ability to store as much energy as a larger Battery intentionally made for Cars to deal with the Cars requirements for being able to sit in storage a reasonable amount of time, to start in freezing weather, to run emergency lighting and other factors. So that is why we say its best to go with a minimum of 30Ah and 40Ah is better, and 60Ah is best.

3- We do have tons of people running these ATX20HD (15Ah) and the ATX30HD (24Ah) in the Tuners, Racer, and other Street Performance Vehicle as I said... but for Porsches its sort of a different animal being that alot of the smaller Cars also use smaller Lead/Acid batteries too...

4- I understand you are confused about the PbEq Amp Hours we state. Per our website and Box we show a real "15 Amp Hours" for the Battery and then a "PbEq Rating" which is 30Amp Hours The PbEq raiting is a rating to give the Consumer a general equivalancy in performce to a LEAD/ACID Battery. So for example our 15 Amp Hour of Lithium Battery will Perform as well as a 30Ah Lead/Acid Battery. Pb- stands for Lead Acid, EQ stands for Equivalent. But if you notice, you will see that Porsches come with a 70 and 80Amp Hour Lead/Acid Battery so even a 30Amp Hour Lead/Acid is half the Capacity of what Porsche comes with and we are claiming our 15 Amp Hours Lithium can replace a 30Ah of Lead.... but it can't replace 70Amp Hours of lead... we say our 40Amp Hours Auto Battery is the replacement for the 80Ah stock Porsche Battery..

Hope that helps describe it a bit better... if you confused give us a call and I can explain it very easy over the Phone... its hard to type it out.

mc3456

So then, do you recommend the 40Ah or 60Ah to replace the OEM battery? How big of a difference is there regarding how long a car can sit undriven for somebody without ancillary items (dash cams, radar detectors, etc.)? Lastly, when is the next sale, or Rennlist Group Buy? Thx!

blackcheetah

Thx so much for your input very educatif, my last porsche was a 996tt 3.8liter with the same battery