Lithium starting battery

It's been over a year since I've been on this thread. In the meantime I resolved the questions I had about the way the EarthX charges, and have been very happy with the EarthX. In May I embark on a long trip to Alaska, so want a second battery, both for in flight backup and as a second starting battery in case I am somewhere remote without any ground charging ability. My thoughts are to simply install a second identical Earth X and wire the batteries through a boat type switch, allowing choice of Bat 1, Bat 2 or both and Off. Plan would be to fly on Bat 1 one day and Bat 2 the next to keep both charged. I believe there are some automatic battery switching options out there, but cannot source any. I'd just like to get some feedback from the forum.
Blue Sea Systems makes a whole series of battery switches. I'll check my catalog. Have used these products for ages.

So if you are using an external starter pack no weight or chemistry issues. Why go lithium? Use a simple lead acid pack.
I have a 28v start cart that plugs into the 124v 60Hz AC wall outlet in my hangar with a long cord, and I use it for cold weather starts in my turbo Bell 47. No batteries in it at all.
There is a non lithium alternative to replace the lead acids with the advantages of lithium without the downsides of lithium.
So I finally got around to installing a second backup battery with a boat switch.Lithium starting batteryLithium starting battery
a 2nd starter battery so, when the 1st one fails you'll have a backup to start the engine
Yes, I have a trip to Alaska planned. Main objective was as a second starting battery.
I also tested it while running, switching from 1 to 2 quickly, and there was no power loss noted. So also in the unlikely event of loss of a battery in flight it would seem to work.