On 06/05/2018 01:11 PM, Martin Gregorie wrote:
On Tue, 05 Jun 2018 11:42:49 -0700, Frank Whiteley wrote:

Sadly, not entirely unrelated to this thread. This was the plane used
in the recent glider tow.

https://electrek.co/2018/06/04/sieme...rototype-fire-
crash-death/



A few years back there were a lot of cheap LiIon batteries on sale as SLA
replacements that turned out not to have a BMS system - just cells in the
case. Obviously, these would be at least as flammable as an SLA of
accidentally shorted.

Replace "at least" with "far more'. SLA's are way down at the bottom of
the list when it comes to flammability.


IIRC these were impossible to distinguish from batteries with a proper BMS
inside the case, so, are they still around and being sold to the unwary?



Not sure what a "proper" BMS board is. There are a variety of functions
that may be included, the data sheets tend to vague on what's in there.
See Wikipedia for a primer.

If the battery can disconnect itself from the terminals in the event of
excessive discharge current, too high of charging voltage, or too low
voltage on discharge, then it requires some high-current switches to do
the job. It's a dangerous assumption to think that a battery must have
those capabilities included.