Adding to the above.....
Go look up the "off the grid" folks' charging systems. Many turn off the charging and look at the batteries. Maybe apply a small discharge mechanism, even as simple as a resistor.
As I posted on another thread, sometimes it's the simple things versus the high-tech, latest and greatest stuff that gives you problems. Like the charging system.
The Li-ion batteries are great for power density, size and such. But ya gotta be careful when using them without good monitoring systems for charge and such.
One biggie is the failure mechanism of the Li-ion batteries when they decide to go "thermal". They are not like the older batteries, including the nickel-metalic ones that are not that old. No need to go back to Ni-cad or lead-acid car batteries. The item of concern is what the Li-ion batteries do when they go into thermal runaway.
The FAA rules on shipping large amounts of the Li-ion batteries seem to take into account the catastrophic effects of a problem with those suckers. And do I need to remind all of the infamous Value Jet crash due to the emergency oxygen bottles starting to burn? Still cry about that one.