Battery safety (againish)

On Monday, March 18, 2019 at 8:22:43 AM UTC-7, Dan Marotta wrote:
I used LiFePO4 batteries in my former LAK-17a for about 3 years before
selling the glider.Â* I charged them out of the glider for the first year
and, thereafter, left them on the provided smart chargers in the glider
between flights.Â* They had battery management systems built-in.Â* Of
course, there's practically no vibration in a pure glider...

On 3/17/2019 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?Â*
Or is the location of the batteries in this specific glider such
that the resin is advisable?Â* A battery fire anywhere in a glider
(even without a fuel tank) is catastrophic.Â* OTOH I havn't heard of
any fires with this type of battery.Â* It's the lithium-polymer
battery pack (also much larger, with many more cells) in the FES
systems that has had fires.


Well, the service bulletin talks about an LFP that burned. There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not
true.

The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I
would not want to use one, even though the short engine runs typical
of self-launchers means problems would be less likely than in
airplanes. The Earth-X batteries all have a BMS, seem better
characterized, and I would trust them a lot more.


--
Dan, 5J

Of all of the articles and papers I have read on rechargeable batteries, this is the first one that talked about modifying the internal construction of the battery. The mere idea of drilling into a battery scares the hell out of me, and I bet it would do the same to the manufacturer.

Tom