Battery is completely dead now (I think it has been 4-5 years old). I know a couple of folks have installed Antigravity Battery into their v8 vantage, hoping to get their long term feedback on the battery.

1. Is the Antigravity Battery (AB) still as reliable and consistent after years of using it?
2. Did you use the 60ah or 80ah H8 version? Thoughts on 60ah vs 80ah compared to AGM?
3. Can the car with the AB be without trickle charger for a longer time compared to AGM?
4. I may sell my car in maybe 2-3 years, not sure whether it is worth it for me to replace with an Antigravity ($900) or just a AGM ($200). I absolutely hate the "dead battery" and "cannot start car" anxiety. Multiple times my car couldn't start even when it was on trickle charger (could be old battery).

I have a 2011 V8 Vantage S. Thanks all!

 

I installed antigravity battery last winter. It has been great. I have never used trickle charger. Without driving the car for few weeks in the winter the charge never dropped below 90%. Having the ability to turn on the car even if the battery goes very low is very assuring. I really also like the ability to monitor the status of the battery from my phone. Add to that over 20lbs weight loss.

 

Put an OEM equivalent one in, it's not worth the expense or hassle. Ohms law hasn't changed and the little batteries don't play well sometimes. AGM battery isn't a step up as everyone thinks it a better solution. Regular battery and a maintainer will guarantee a cost effective life.

-JW

 

I disagree. Lead Acid battery is old tech, heavy and the residual power loss just sitting idle is really annoying for people that don't drive their cars that often.
LFP battery is worth the investment. Save a good amount of weight even compared to AGM.

 

(EDIT: sorry, I just realized it is flooded lead acid haha, you're right) I guess the most important thing is to have a battery with a vent tube so you can avoid hydrogen accumulating in the cabin.

A lithium ion battery is good if you want to keep the car, because long term ownership cost is lower from not needing replacement and slightly better efficiency. If the car is going to be sold, then maybe toss in a lead acid to save money.

 

I don't know if anyone can give you an evidence-based view on years of using an Antigravity Battery, in their current form with the latest built-in Battery Management System they've only been manufacturing them for a year or so. But, they reckon they will last much longer than lead acid, and I believe them.

Both DetomasoGTS74 and I fitted the 40Ah H6 battery, which I believe is the recommended size for an Aston Vantage. With lead acid batteries (and AGM are just lead acid), we always bought big batteries because we needed a lot of power to start the engine, but an OEM 90AH battery has only 1020 cranking amps. The 40 Ah LIFEPO4 AntiGravity battery has 1500 cranking amps, so the old thinking doesn't work here. With the 40Ah battery you get around 50% more starting power then than the OEM battery.

The other thing to consider is parasitic drain on the battery, and this is where the Ah numbers are relevant. If your car has a fault and something like a tracker or dashcam stays active when the car is switched off, then it will drain the battery. If its using electricity like a 5w lightbulb, then a 90Ah battery would be dead in around 9 days, a 40Ah battery would be dead in 4 days, but, with an AntiGravity battery, the BMS would switch off the power and stop the drain, so if you came back to the car after 20 days, it would look dead, but press that button on the battery's remote, and it would switch back on again and you could start the car and drive away, so in a sense the Ah number on the battery isn't as important.

Ctek and others make a special Lithium battery charger for these type of batteries, so they can be hooked up to that for years without damaging the battery. A standard charger might do its lead-acid regenerate which does clever pulsing things to improve the life of a lead acid battery, but those things will kill a lithium battery.

Final thing to say is the physical size of the battery, OEM is an H8, which is 349 x 178 x 190mm. Lithium batteries don't need to be that big, so Antigravity and others put the little lithium cells in a big box to make things convenient for us. I went for a smaller than standard H6, which is 311 x 178 x 190mm, and use the space it frees up to keep a can of tyreweld in the car. The battery leads in my car (2010 V8 Vantage) are long enough to reach the terminals on a H5, so I wish I'd gone for an even smaller box, but don't know what I'd have put in there ...

 

An H5 case's internal volume is big enough for approximately 60Ah x 4 of lithium iron phosphate cells, maybe a little less, so it's not like the plastic case is a massive waste of space. The internal resistance plus increased voltage of a high-current LFP (manganese containing cathode) makes it "equal" in cranking power to a lead acid battery several times bigger, while the increased cycle endurance and higher voltage at low state of charge makes the useable capacity maybe 50% greater.

Basically, just size the battery according to parasitic draw, and make sure the alternator's rated amps - 30ish A is not more than the max charging C-rate * the battery's capacity. So with lithium iron phosphate, anywhere from 30Ah to 60Ah would be sensible on these cars as they should not exceed a 3C charge rate, though 60Ah is probably kind of excessive. On an older car e.g. a Lotus Elise or Toyota MR2 has a 90A alternator, it's safe to go down to 20Ah. If the car is always plugged into a charger, then you can go even smaller.

 

Do the original OEM brackets and mount (that came with the car) still work with the H6 battery? That was my only concern, not being able to mount other sizes properly.

I think Antigravity did not have a H8 size until recently, now that they have H8 sizes that matches the original OEM battery, I am leaning towards just using the H8 size.

 

H5 through H8 all have the same height and depth as well as identically shaped plastic protrusions around the bottom. You use one or two of the sliding clips at the bottom of the tray to hold the base in (the batteries are designed to be held by the plastic tabs at the base). They're very strong, if you look at a Porsche battery tray for example, they use the smallest two tabs along the short edge to hold the battery in.

I have an H5 sized case in my car, I just used a single clip and took off the second one, and also took off the support bar that goes over the top of the battery. Trust me, you'll like the smaller battery, it is much easier to maneuver in and out of the cubby space.

 

I already took out my existing battery. It is completely dead. Hated the metal bracket.
(1) Did you still use the metal bracket or just the sliding ones at the bottom?

I did not realize H5-H8 are the same enclosure. Couple of other questions:
(2) When the Antigravity battery BMS decides to "shut down" because voltage is getting too low, I assume it shuts down all the v12 electronics (doors, etc.) on the car? Can I still unlock the car via my remote after I press the remote Restart/Jump start feature?
(3) If in the event that I do not have my remote start key, can I still jump start by traditional means via jumper cables? (I think so, just double checking)

 

The mounting for the H5-H8 batteries are all the same, just the batteries are longer. On my H6 I used the two sliding brackets at the bottom, and took off the metal bracket over the top, reasoning that it was there to hold a very heavy battery in place, but with something as light as a lithium battery there really didn't seem to be any point having it there. Removing that bracket saved a further 344g, it all adds up! I also removed the foam, couldn't see the point of it, and that was a further 174g gone.

When the Antigravity BMS shuts down the battery because its getting too low, everything will be cut off, so it isn't something you'd want to do, but that is much better than the alternative ... I'd actually be terrified if I had a lithium battery without that shut down feature, because if you flatten a lithium battery, its dead forever, and you have to buy a new battery, dead means dead. There are people that can dismantle the battery and install new cells in there, but that isn't something I could do.

If you forget your remote, then you could use your mechanical key to open the door and on the top of the battery is a button that serves the same purpose as the remote, it will restart the battery. If you've also forgotten your mechanical key, then you've as stuffed as you would be with a lead acid battery, but if you can find a way in to the car, hit the button on the battery, start the car, and go for a drive to give it a nice recharge. You do get two remotes, at least, you do here in the UK, so you could always hide a remote somewhere on the car, perhaps under the bonnet, so that you can restart the battery, open the car with your normal key, and start the car as usual.

You shouldn't need to jump start the car, which is good, because putting a huge jump starter on the leads under the bonnet is likely to destroy your battery. If you need to get power into your battery before it can start the car, then put it on a lithium battery charger for a few hours and then start the car as normal.

This might sound really inconvenient, but remember, if you get to a point where a lead acid battery would be dead, the Antigravity will have shut down and should have enough in reserve to start the car.

 

Thanks for the detailed response.

The reason I ask is because I think the Antigravity battery will shutdown faster than a AGM? Correct me if I am wrong but:
- AGM will last longer powering the small electronics (including getting into the car via remote to access jumper cables/jump starter) vs AG which will likely shutdown faster than the AGM killing all electronics, including the remote entry (in which case I cannot even get into the car to get my emergency stuff)?

In short, is it true that AGM will last longer still powering normal electronics (including remote entry into the car) vs the Antigravity which may shut it down faster? If true it means that it becomes more important to have my mechanical key around me because there's a higher chance of not being able to get into the car via my remote?

It is difficult to compare the ah rating on AGM vs lithium ion, but roughly (AGM has a 100 Ah @ 20h rating) vs (AG which you can spec at 40/60/80ah).

 

An AGM has no BMS, so it will shut down when it has no charge left, the Antigravity will shut down earlier, but can be restarted, if necessary several weeks later, and should still have enough power to start the car. You get a remote with the Antigravity (plus a spare), that remote will restart the battery from outside the car, once its restarted, power is restored to all the car's functions, then your remote entry will work, and your starter motor will work. But having the mechanical key with you is a good idea anyway, I've carried mine with me everywhere for over 10 years, and only needed it once. That was when I used a lead acid battery.

The Ah rating on the different types of battery is comparable, 90Ah means the battery will provide 90Amps for 1 hour, or 1 amp for 90 hours, or half an amp for 180 hours

 

It'll take well over a month to discharge a 40Ah battery. If you do that to a lead acid battery regularly, its lifespan will be drastically reduced. Trickle charge the car if it's going to sit for months.

 

I completely understand that, and that is exactly what I am trying to figure out in the event that I am outside and I only have my remote keyfob. I usually only carry my remote keyfob outside, and I do not want to be caught unexpectedly when Antigravity BMS shuts itself down and I cannot even get into my car since I only have the remote keyfob.

Sorry that my explanation maybe a bit confusing, and that I may have an unnecessary concern. This is my understanding:

- AGM rating is roughly 100 ah @ 20h = 5 amp for 20h (full discharge)* will try to keep the car electronics alive as long as it can
- Antigravity rating could be 60ah = 60 amp for 1h = 6 amp for 10h = 3 amp for 20h (full discharge)* BMS will shut off even earlier to allow remote jump start

That sounds to me that considering that the battery is low on charge, with Antigravity battery, there is a higher chance that Antigravity will shut itself down faster than the AGM. This means that I cannot even get inside my car if I only have my remote keyfob. With the AGM, although I have a higher chance of not being able to start the car, but I have a higher chance of still being able to unlock the car via my remote keyfob, and access my emergency jump starter/jumper cables inside my car.

My basic concern is that with the Antigravity, it becomes more necessary for me to carry the mechanical key or the remote jump start around at all times (because of BMS shutdown likelyhood), while previously I mostly just would carry my remote key. I wish there is a way to jump start from the app since there's already a communication channel to the battery.

Is there a good place to hide the remote jump start somewhere outside the car so that it does not fall off at high speed?