Battery Brand
 

The brand of battery was 'Extreme' and was indeed Lithium Ion. Apparently used by many experimental light sport builders and purchased from a dealer.
(Or was it a Samsung?!)

So if he jump started it I'm sure it went to full amperage charge, I know these things are sensitive to the amount of current in, they don't recommend jump starting a dead Lithium, rather charge it with the appropriate charger.

When Li gets too much heat and pressure
 

https://youtu.be/b5tmkna-k-U?t=1m17s


Only historic entertainment about the Castle Bravo miscalculation.

I believe the Earth X Lithium Iron batteries are developed to the point that I might try one in my own AC. As with any type of battery it is important to understand the ideal environment and use. More important is to understand what happens in a less than ideal discharge / recharge and temperature/vibration environment.

I like the thought of a sealed SS battery box with external ventilation.

Absolutely
 

Absolutely!

Jumping to Start
 

As an aside, to start the plane we jumped the starter rather than the battery.
The battery was installed so that the recommended (provided) charger was charging the battery and the Rotax charging system was actually feeding that charger.
Whenever I saw news shots of burning or exploding hover boards or phones, I think I subconsciously just assumed that those things happened to 'other' people.
Wake up call, to say the least.
But we both just ignored the fact that these things do not like to completely discharged, even if it IS our fault and we didn't want to trash a brand new (one hour old) $175 battery.
Lessons learned with no harm to anyone (except to the wallet).

Thanks for posting this info, but we would still like to know the brand, and did it have a battery management system built into the battery like EarthX?

Post 11 above. Sounds like it was an "Extreme" brand Lithium ION. No indication of BMS from a quick SOTW.

I searched, no, I did an extreme search for Extreme (including xtreme) batteries and found an extremely large number of offerings with a lot of extreme names. Maybe an extremely astute VAF member could narrow the field to definitively identify this battery model and manufacturer. It would be extremely helpful. Xtremely.

"new and improved"

Battery Brand
 

When I get back to my friend's hangar this weekend, I'll try to glean some brand information and/or part numbers from the blackened/burned case of the battery.
But it DID have a battery management system incorporated into the installation.
He's replacing it with an AGM sealed battery.

When people started using Lipo batteries (yes not exactly the same I know) in models there was a learning curve. People put crashed models in the trunk of their car and their car burned to the ground. Word got out via the internet and people started keeping buckets of sand at the flying field and at home and carrying their batteries in either steel ammo boxes or those portable fireproof home safes. Then came packs that were tapped for balancing circuits, smarter chargers, and just people being generally more careful. But I have a friend who had a major fire in his garage while charging and had he not been right there he could have lost his house.

So I would certainly consider a stainless and insulated battery box of some kind. Fire in a house or car or at a flying field is bad, but in an airplane at 2000 ft it is a whole different level of badness.

These batteries most likely can be dealt with by having over-voltage control, balancing and general battery management and protections on the charging circuit. But our homebuilts are so varied in the configuration of their electrical systems that it is really hard to be sure you have something robust. We won't do the testing for every scenario that a certified mfg will do, nor will we have the configuration control that they do. And look at what happened to Boeing with the 787 and they did tons of testing. Now the battery chemistry might be somewhat different than what Boeing had on the 787, but the overall concept is the same. This class of battery seems to be more sensitive to abuse and they seem to be much more liable to catch fire than an AGM battery. It seems like we are not yet there with the level of safety. The fires may be rare, and maybe they are usually the fault of the user, not the designer (I don't know) but when it happens it is real bad. We are all responsible for our own level of risk, so go in with your eyes wide open and a backup plan. AGMs still look real good to me. I'm sure we all could save that weight by more healthy means - like exercise and reducing carbs (guilty).