I have to say I'm not really comfortable with LiOn battery technology for starting cars. The technology has been around for over 40 years, but it was only in the 90's that Sony made it practical by introducing onboard software that monitors the battery and shuts it down completely (bricks it) when it senses the battery is at the end of its life.
This was found necessary because unlike old lead/acid technology LiOn batteries fail to an effective low resistance, drawing substantial current from the charge source that can no longer be absorbed by charging the battery. It does instead simply dissipate the power in heat, eventually melting the body or exploding, unless some mechanism is in place to terminate. You only have to look towards laptop recalls in Japan, Boeing 777 groundings and very recently on a popular top of the range Smartphone to realise this is an ongoing issue.
This leaves me with two concerns, the possibility of the bricking software failing no matter how remote, as the consequences would be severe in this application. Also the strong likelihood of the software bricking the battery prematurely with no warning, since manufacturers are going to err on the side of caution. I have heard that max five years is typical in this application which I agree may be regarded by some as adequate but maybe not given the price.
