thunderdent

Quick question for the board.

The time has come to replace the battery in the GT3RS (991.1).

The original option was checked for the lightweight battery option.

I just upgraded my R8 with an H7 Antigravity Battery and love It.

I ordered an H6 Antigravity battery from my same vendor, and it arrives tomorrow.

My question is this. What are these plug-ins on either side of the OEM battery? How will the new battery work with this? I know other people have upgraded to Antigravity, and they even sponsor this forum.

How will I plug these in? What happens when I don't? Just the ones I have circled.

(please ignore the extra comfort cables I have hooked up for the trickle charger.)

Thanks in advance for the help!

FourT6and2

My RS (.2) didn't have those plugs. Never seen 'em before.

EDIT: Whoops, you have the motorsport battery. Not sure what those plugs are for...

thunderdent

Interesting yours doesn't have it.

Anyone else the ticked the "lightweight battery" option on their spec sheet have this battery?

I have my AG battery rep checking into it too. He's never seen it before.

I don't want to switch to something that won't work with the car.

GrantG

I would guess that the plugs read from the battery what type of battery it is (that it is LiFe battery with 40AH or whatever), so that it knows the proper charge voltage and current (a bit different than lead acid). I think there may be a way to designate the settings you want with the PWIIS tool to work optimally with the Antigravity (that I think has its own electronic brain to maintain proper voltage and current charging).

Or if we are really giving Porsche credit, maybe the electrical plugs give information about the voltage of each individual cell to ensure balanced operation. Balanced charging is safer and extends the life of the battery.

If you remove the plugs and read the pins with a DC voltmeter (with one probe to ground), you may be able to confirm this (should be around 3.3V per cell or something like that). Be careful not to unintentionally bridge two pins together with the probe.

thunderdent

I did find this.

https://rennlist.com/forums/991-gt3-...m-battery.html

His bullet point #4. I'm assuming that means just leave it unplugged. Thoughts?

GrantG

Interesting - I guess his recommendation was to leave unplugged, but probably best to hear it from him or someone at the dealer.

Antigravity

Well, sorry for the delay.... I did a whole response yesterday, and got busy forgot to press submit, then closed out my Google window.... so here is goes again.

Per my picture below you move the "plug" that is on the Porsche Lithium Battery, over to the Intelligent Battery Sensor (IBS) located on the Negative Battery Cable. As and FYI Porsche designed their Lithium Battery to transmit its data such as voltage , current, temperature directly from the Battery on its lithium batteries to it computer system. But, the fact is the IBS does exactly the same thing and transmits those data points, but it just relays from the Battery connection itself rather than from the internals of the Battery. So you can move that plug from the Battery over to the IBS and plug it in there. Also there should have been a cover on the IBS plug in area so see is its corroded in there. This plug HAS to be plugged in or the Car will not know the voltage and status of the battery and will probably throw massive flags. You may have to update the PIWIS setting for the Battery to AGM when you do this since it is now reporting from the IBS,. Also the Lithium Setting in the 991 is not the best setting for the Charging profile because per the Porsche Bulletin it charges at a max rate of 13.8v, which is FINE and a little better when tracking only, but for regular driving without sustained high RPMs it better to use the AGM charging profile, even on our Antigravity Lithium Battery.

As and FYI, I personally owned and tested our Batteries extensively in my 2016 991.1 GT3 RS. And it has this exact plug, plugged into the IBS since I had the AGM Battery in the Car originally, not the Porsche Lithium Option. So I know about that plug. As far as the other plug on the other side of the Porsche Lithium Battery, that is Battery plug that won't interfere with anything for the Car, but I don't know what it is.

FourT6and2

Good info. Question about something you mentioned:

You said that if "tracking only" it's better to update in PIWIS because you're at high RPM a lot. Well... I drive on track and on the street. But I'm at high RPM on the street a lot too. You know... driving canyon roads, twisty mountain roads, etc. But it's not as sustained as at the track obviously. And when I go to the track, I drive there. So I'm on the highway for two hours sometimes. Not at high RPM. But when at the track... all bets are off. I've kept the car set to regular battery setting. But are there any potential alternator issues long-term by doing so? What about potential issues to the AntiGravity Battery?

Either way, my battery has been performing great since install. It did throw a code at one point (which we talked about). But after resetting system, no issues. Must have been a fluke. I also didn't drive the car for almost 5 weeks (no battery tender). And it started right up without hesitation.

thunderdent

Thank you for the response on the plug-in location! I'll swap the plug over to there when I install the new H6 AG Battery.

I don't have a PIWIS. I assume is the same type thing as my VAG-COM Audi cable. My closest Porsche dealer is 3 hours away. And my battery is dead, so I have to change it myself.

Is there another way to change the battery profile to AGM?

I also purchased the CTEK Lithium trickle charger from my AG rep. So that is the correct one to use? I'm using it on my new AG battery (H7) I just put in my R8.

thunderdent

That cable seems to be just an OBD reader.
Would my current cable work? Link to a place for the software?

thunderdent

An update here.

I removed the Porsche Motorsport Lithium battery.

I removed the plug from the battery.

Replaced that battery with the new AG battery.
(Batteries are close to the same weight, Porsche one actually seemed just a hair lighter, but I didn't weigh them.)

Plugged the clip into the negative terminal as you showed above (there's actually a small diagram sticker on the OEM battery telling you where to plug that for each type of battery) It also confused me earlier because it had the Li and the Pb both on the sticker, I put it on the original Porsche maintainer on the AGM setting because I saw the Pb on the sticker on the OEM Motorsport battery. So I prob fried the damn thing doing that with desulphation mode. But I digress.

Back to the new AG battery.
Everything fired right up. No codes.

I did put the new AG battery on the new CTek Lithium Ion maintainer.

I have not changed the vehicles computer system to the AGM setting instead of the Lithium setting it is currently coded for my car. I have no way to change it, and I don't have a local Porsche dealer close to me. My thoughts are the CTek Li maintainer will keep the battery to where it should be. When I drive the car, the alternator in the Lithium setting will only charge it to the 13.8v. Which isn't going to hurt anything. And then when it goes back in the garage, it goes back on the maintainer.

So I'm not too worried about it. The AG is a lithium battery. I don't have a way to change it, so I'll likely not bother.

Antigravity

Hey Four,

There is not problem with either Lithium or the AGM PIWIS setting to our battery whatsoever. Both work fine. The Porsche theory, as I understand it, for having the Lithium Battery Charge Profile as a lower max voltage output (13.8v) in PIWIS for thier Lithium Battery was that a lower voltage at max RPM reduces the overall drag on the motor that the alternator would cause on the the motor is having a higher charging voltage. In reality this is insignificant until you are racing or just a monster on the track looking for every micro-second of time. It was also due to the fact that the Porsche Lithium Batteries did not handle higher rates of charge as well. Unfortunately it was honestly not a good lithium battery and had tons of failures because it just wan't programmed great and had some oddball issues, that info comes from the fact that early on I tried to get one from Porsche to compare to ours and they told me they were having failures with it and did not want me to buy it... I got that from two dealer. The I met a few who had it fail. I don't know exactly what the failures were alot so they pulled selling it later on.

So the problem with the lower voltage charging in the lithium setting is not a massive problem, but it just not an optimal charging rate IF you are using extra accessories, driving at night or other times that power accessories. For example if your driving at night stereo on and stuff. YOu want your battery to be able to keep fully charged. Also as you know you are on the track many use the A/C because it can get so hot in the suit and at the tracks... so you want full power from your Alternator to power the A/C. Now being honest in the end I have not tested for needing 14.6v during using the A/C but it just logical you want full charging and power from the alternator when using high-draw accessories. Porsche intended their Lithium PIWIS setting for the Track... it says so in the bulletins sort of.

Antigravity

I don't see a problem with it being honest.... just check the voltage of the battery every so often initially and see that it staying at 13.2 after it sits a few days. Its awesome you got no Codes. I figured it might when you switched the Plug since perhaps the reporting of the battery information might be different, but that is great news. Another thing learned.... I had never seen anyone do the swap yet because only a opted for the Porsche Battery since I think they were like $5k back in the day for that option...

thunderdent

Good to know on voltage. I figure I'll be fine for the time I drive it.

I also don't run a ton of accessories.

Here is the pic of the sticker on top of the battery telling you what to do with the plug. I didn't understand what it meant it at first. Which is why I tried to charge it on the incorrect AGM setting with my Porsche maintainer.



I'm the second owner on my car, so I didn't tick that box for the OEM Lithium battery, but here's the options list and price upgrade over standard AGM.



Again, I didn't weigh both batteries, but they are very similar in weight. Possibly a small advantage to the OEM. But the AG is a better battery with protections, jump start, and remotes.

If I ever find myself at a Porsche dealer (or other) for service with access to the PIWIS, I'll have them swap the setting.

Thank you for all the help.