Howdy everyone,
I've been following the Lithium battery field for about an year now. I'm very interested in it, as the technology seems to offer a lot when compared to lead-acid.
Regarding fire safety, not all Lithium batteries are created equal: depending on the specific chemistry (ie, what other substances it uses, apart from lithium), it could be safer or riskier. In fact, Lithium-Cobalt batteries are much less safe (but also costs much less for the same capacity); it was those that caught fire in the Boeing Dreamliners. Lithium-iron-phosphate (aka LiFePO4) are much safer, and are considered fire-proof as long as one doesn't do anything stupid (like shorting the battery terminals, and even so some reports tell us that the piece of metal/wire doing the short burned away but the battery itself didn't ignite), but then they are the most expensive in a dollar/Ah basis.
An interesting middle-ground is apparently offered by lithium-manganese oxide (aka spinel, or LiMnO4) batteries: safer than the cobalt batteries (although not as much as the LiFePO4 ones), but not much more expensive. These are the batteries being used in the Chevy Volt (with added compounds), and a DIYer can apparently get a good one from a wreck for about $2k and enjoy 12KWh of energy storage, which is an absolutely stupendous amount, and would be cheaper than even than lead-acid... this is one gentleman who is going that route: http://rvnerds.com/2016/01/18/new-project-installation-of-a-new-lithium-ion-house-battery-bank/
As for LiFePO4s, +1 for the Technomadia site: they have been using these batteries for almost 5 years and reporting on their experiences all along, so there's a lot of material there. For someone who just started down this route, I recommend watching the latest WheelingIt posts: http://wheelingit.us/2016/02/24/the-big-beastly-solarbattery-upgrade-part-i-why/
Me, I'm still about an year off having to make that decision, and I hope the situation becomes clearer so we can have lithium batteries in our own rig right from the start.
Cheers,
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Vall