Using the Elite Power batts as an example, 200Ah weighs 55 lbs. An equal Ah of flooded batts weighs almost double that, For AGMs, the weight is the same as flooded. So you save nearly half the weight. Physically, LI has a smaller footprint too and can be "shaped", at a cost it seems, to whatever the market wants. You don't need grp 27, 31, GC etc unless you want to. Your laptop battery can't really be used as a comparison because it's LiCo. Chemistry is different than LiFePo4 (LFP). LiCo is a LOT more energy dense and requires active cooling. Operating characteristics are different. Probably a Google search that compares the 2 are in order (I need do to the same). BMS is a prime example of the difference of LiCo vs LFP. You really don't need one for LFP but you better have one for LiCo.
