Tesla isn't "detecting" LiFePO4 batteries at all -- they just happen to not behave exactly like Tesla expects their OEM lead acid battery to behave. That anomaly is what flags a "battery issue".@android04 - I didn't mention Lead Acid at all.
My point is that if 11 lbs gave you 44Ah (perfectly reasonable for LFP), than 14Ah wouldn't weigh 9 lbs. It would weigh about 3lbs. There's no way the V2 was only 14Ah, and if it was, it was hugely overpriced and had a lead weight inside. That was my only point that your 14Ah estimate was not accurate.
You're driving yourself in a logic circle. Lead acid was 44Ah, so V1 was 44Ah, but you really can't use that, only 10-20Ah, so V2 was 14Ah, but now V3 is 44Ah again, because that will fix the errors this time. Plus, just because you should only use 20% of a LA's capacity doesn't mean it doesn't have 100%, and when you measure that battery, you will measure it at 100% capacity. If the charge algorithm was expecting a 40Ah battery but then was only going to use 10Ah of it, it would still expect to see 40Ah, and you can't just hand it a 15Ah capacity battery of different chemistry and expect it to be happy. It should rightly freak out when it thinks your 40Ah battery has degraded to 15Ah. This is not just a dumb float charger.
Tesla is not detecting LFP via capacity measurements. You can see this because they will throw an error long before they would be able to estimate battery capacity, and over the fact that they throw errors even when a very equivalent capacity battery is present. They're using other characteristics of LFP, such as higher float voltage to detect the different chemistry and this is what all LFP 12V vendors are going to have to figure out how to work around.
And no, Tesla will not be able to measure the full capacity of the lead acid because to do so would drain it and kill it really fast. Tesla does measure how much charge goes into and out of the battery through a shunt and uses that info to determine if there are any issues. Of course, they try to account for any charging losses, etc. This is the reason why you might hear people say not to tap directly into the 12v battery for things that might drain too much power, because that drain doesn't go through the car's shunt and the drain isn't measured or accounted for. Which could cause the car to think your lead acid battery is failing.
My point about Ohmmu possibly reducing the battery capacity in gen 2 is that it was because the car doesn't actually cycle the full capacity of the larger battery, and it's therefore a waste. Or that the larger actual capacity can cause issues if the battery happens to be, or gets, low enough to need a charge much greater than the lead acid would take. In this scenario, the car it's keeping track of how much charge is going into the 12v battery and it's greater that it would be for a lead acid might determine that there's a shorted or dry cell in the 12v battery.
Now to get back on subject, I've come across the Antigravity batteries before when researching possible replacements for my Model 3's lead acid battery. A few things ruled out out for me:
1. The closest fit battery available then was the ATX30-HD model, which required battery terminal adapters (not a big deal for me, since they can be had for about $15).
2. At $560 it was more expensive than even the other LiFePO4 batteries I was looking into (Ohmmu, EarthX, ReliOn).
3. The info on battery didn't specify if there was a low temperature cutoff.
That said, it's nice that they now have a group size 51R battery that we can use on our Model 3s or Ys if we want to. Hope to hear feedback from users. My original lead acid is still working fine in my Model 3 after more than 4 years and 78,000 miles, so I haven't had to replace it yet. And I won't replace it until it fails because I'm prepared to handle it. I can easily pop open my frunk and jump start myself.