Ok Let me expaint how system work : 1st : It has battery sensor connect with the ECM thru Lin bus which on the negative terminal 2nd : alternator connect with ECM thru lin bus also.. so basically : the Battery sensor sence the Capacity of the battery, if it saw the battery get weak, it tell the ECM to Command the alternator charge it. But for some reason, the battery sensor on our F12 or 488 or 812, it can't read the Lithium battery, so it doesn't know it fully charge or low on charge, so it just sent the wrong signal, on off on off all of the time, so for long term use, it will damage our Electric system I believe. car got safety feature, example when ECM doesn't see the Command from Battery sensor, ex battery sensor is dead, for safety it tell the alternator to charge all of the time. But if we disconnect battery sensor, we got error on the dash. so the best way is find the battery sensor which understand the lithium idea, then we will have proper working system our F12 got very low Current drain after all module is sleep, only 10 Mili Amp, so for my F12 with AGM now, I even don't use the battery tender, car still start normally after 2 week or 3 week
Just bringing this thread back to life, I have a new battery, installed in the fall, and after a drive it is giving me the lazy start issues. You said there is a second ground cable. Where on the battery do you connect this second cable, and where does it connect? Does it connect on the alternator? I want to explain this to my dealer, its damn frustrating not knowing if the car is not going to fire up. Thanks!!
you are correct i have the antigrav lion battery in my F12 and it does not charge regularly on drives. it's almost opposite of how a normal battery charges, like when you are cruising at highway speeds you charge normally but with the antigrav you don't, and when idling at a stop normally doesn't charge battery much it does on the antigrav. no idea why. as for relocating to trunk i think it is impossible because of the lack of proper wiring you would need a lot of special insulated wiring to bring power from trunk up to all the systems in the engine area that need it.
