There is another battery technology that is purportedly being developed in Japan that isn't Lithium based, which is supposed to be the next step up in battery technology. I forget what it's called, but reportedly doesn't have the issues with thermal runaway and a finicky battery charger system and temperamental cell charging behavior.
What the letter said was basically the lack of standardization of the different lithium technologies, along with required maintenance and other problems and danger outweighed the advantages.
Here is their conclusion:
The Future Of Li-ion Batteries
Li-ion batteries have a bit in common with propane tanks: They're a high-energy storage system that is potentially dangerous. Fortunately, with propane, we (usually) manage to avoid disaster. But propane systems have a complete set of American Boat and Yacht Council (ABYC) safety standards that govern their installation and use. While the ABYC is closely following developments, Li-ion batteries are an evolving technology, one that the aircraft and auto industries still haven't perfected. Until the market narrows down to one or two chemistries and reliable, robust battery management systems, it's all but impossible to develop standards for the safe installation and use of Li-ion batteries on boats.
While Li-ion batteries may just revolutionize heavy-duty energy storage someday, the costs and risks still outweigh the benefits for most recreational boats. Until more data exist on which type of Li-ion batteries work best for boats, and what unexpected issues may arise, Seaworthy recommends that most boaters steer clear of these compact, high-energy batteries. For the few boats where the benefits of Li-ion batteries might outweigh the expense and the risks, such as offshore racing sailboats and tournament bass boats, we recommend that the systems be professionally installed and professionally maintained.
