12V battery substitute: $99 LiFePo4?

"Smart Battery" is another company offering "plug and play for almost any application that currently uses a lead acid battery". Good price at $350 for 25AH, but the max charge current seems to be 25A so I'm confused as to how they figure it can be dropped into the average LA charging system with a 100A alternator, for instance.

 

This one, going on 4yrs in my 2010

UPG 35AH 12V DC DEEP CYCLE SLA SOLAR ENERGY STORAGE BATTERY | eBay

 

I have an intermittent dash light, as I'm reading here the 12v starter battery as being the first suspect. I get optimas at OReillys and if one goes bad you exchange it.. I have gone through a few these this year for the price of one. I like to modify vehicles as most of the time being careful, studying all about what your changing and building it. My Ford has a marine regulator and 4 type 31 that run a 2000 watt pure sine wave inverter. I have a boat battery bank with 00 power and ground 27'. I dropped a 67 Ford 302 into an 84 cj7 and it had a BAR aluminum blessing glued to the dash. T-18 with Granny low. Anyone with the desire to think outside the box and be smart about it enjoys the moment you turn it on and it works perfectly. That moment makes it all worth it.