We discussed already some time ago the temperature range recommended by the cell manufacturer compared to the temperature range an aircraft operates in. It looks like nobody has reliable data about the temperature in the electronics bay of a transport aircraft. Especially no data about the regularly experienced temperature cahnges, the extremes when parked in Sibiria overnight or in Dubai on the tarmax at noon with all electronics running is quite predictable, but the temperature range in the electronics bay during a typical moderate climate to moderate climate (via frosty stratosphere) flight seems to be widely unknown.
The 787 Batteries have no cooling system.
Which is strange, as other high performance battery applications even have full temperature control (cooling
and heating), for example the Antares motorglider or hybrid cars. Typically the energy used for heating is smaller than the increase in battery capacity with temperature, so you win available energy by spending some on temperature control. KISS can sometimes make you keep something
too simple...