I made this aluminum and carbon fiber battery mount for a Ballistic 3.5 lb. battery - net savings 25 lbs.
What went wrong with your Braille eyeballs? I used one for years with no issue. I think it was the 11 pound.
How does it affect boosting people off? Will sitting with the radio on and the car off or leaving the interior light on all night drain the battery?
I would prefer an 20 lbs battery in the trunk/boot instead of a lightweight that I should pay attention not to leave the radio ON for more than 2 minutes.