[ealingj]

Took the plunge and gave it a try.

The size which fits the GTM tray without any modification is the Anitgravity Group 75.

From their website:

• LxWxH: 9 x 6.85 x 7.85 inches.
• Amp Hour Options: 24Ah, 30 Ah, or 40 Ah.
• High Power: 24Ah=1000CA, 30Ah=1200CA, 40Ah=1500 Cranking Amps.
• Exclusive RE-START Technology: Wireless Jump-Starting built-in; just press the button on your Keyfob remote.
• Complete Battery Management System built-in.

I bought the 40 Ah version.

Weight of Group 75 Antigravity 40 Ah battery: 13.3 lbs.
Weight of AGM Diehard Gold 775 CCA: 42.2 lbs.
Savings of: 28.9 lbs.

Experience so far:

Love the weight savings.
The way this battery cranks the motor sounds totally different. The motor cranks so fast and effortlessly it sounds like a 2021 late model supercar. Awesome!
Haven't had the slow crank of heat soak after driving, letting the sit for 5-10 minutes, then trying to start up again. It just cranks like a champ. Sweet!
I've had it for about a month so far. It's been excellent.

Stuff like this make me love this car.

Was it expensive? Yes. Did I agonize over buying it for about a year? Yes. Was it well worth it? So far - Absolutely.

 

[ealingj]

 

[TSGTM]

Thank you for the info!! What is the cost of the 40Ah battery? All the best!!

 

[ealingj]

About $830 for the 40 Ah group 75 battery.
About $85 for CTEK smart Lithium Ion charger.

Pricey stuff.

 

[ChevyChad]

Damn, yes, that is very expensive for sure.. Were you having the slow start when hot issue before? I get that and it is very frustrating. I have a new optima yellow top which is only a few months old and I still have this problem. I read that adding an additional ground to the starter should fix it, but I am skeptical of that. If I try that and no luck, I might consider this if it is a proven solution!

 

[Brastic]

The Lithium batteries are just amazing. They are much lighter, charge faster, discharge faster, do not outgas, you can discharge them below 50% without causing damage....etc. Just about the only issues is the cost and you have to have a battery management system so that they do not catch fire. I am still amazed at how the Odyssey 925 has no issues starting these large, high compression engines. If you do not let the Lithium battery get to zero ever, I could see that battery outlasting the car.

 

[DavidRL]

The Lithium batteries are just amazing. They are much lighter, charge faster, discharge faster, do not outgas, you can discharge them below 50% without causing damage....etc. Just about the only issues is the cost and you have to have a battery management system so that they do not catch fire. I am still amazed at how the Odyssey 925 has no issues starting these large, high compression engines. If you do not let the Lithium battery get to zero ever, I could see that battery outlasting the car.

The Antigravity batteries have a management system that prevents overcharging or overdischarge. Group-75/78 Lithium Car Battery – Antigravity Batteries

 

[JAM1775]

Sold my Cobra but currently have a 2013 GT500. Certain late model Mustang ECU's don't like the Antigravity " Restart Feature" in the ATX-20 ($319). So, I opted for the ATX-20HD at $400. My original battery weighed 32#'s at 650CCA. The little ATX-20HD weighs just over 5#'s and cranks out 900CCA. I did go around $90 for their Lithium Battery Manager which kept her alive during winter storage. It's been 2 seasons so far without a hitch.

ATX20-HD Lithium Motorsports Battery

Hi-Power lightweight ATX20-HD lithium motorcycle/powersports battery. HEAVY DUTY version with 900 CA. Replace lead/acid YTX20, YTX15, more

antigravitybatteries.com

 

[ealingj]

Chevychad,
My car would slow crank at times but it has been starting for the past year so I haven't been embarrassed for a while now. However I still get nervous when it slow cranks.

So far with this battery, the car cranks strong and fast regardless of situation.

1,500 CCA according to their specs. This is twice as much as before.