For those that have the room to fit a battery 280l x 176w x 190h ( including din posts) itech under bonnet lithium cranking battery is doable. Costly but states fully usable 65amps and chargeable via alternator or Via any isolator. at 8 kgs itís cranking rated at 1300CCA.
Costly at $900 bucks but serious power. When my yellow top dies Iíll bite the bullet and try it. I expect there not far of a full size disco size start though on output specs this could drop in as a replacement start battery for the one there now.
This is the only one Iíve seen advertised and warranted as a straight drop in under bonnet Lithium. 2 year replacement.
They claim fully Ozzie battery.
concede a traxide sharing with decent AGM is more economically viable but for those who donít really want to share there start battery for camp duties the full discharge of these batteries gives you serious useable power.
It has my attention anyway.

Turtle