How much is flight time reduced when the batteries say they are heating?

It's an equation that takes into account the battery charge level, the initial temperature of the elements, the outside temperature... there is no firm and definitive answer to your question.  But in general we can say that this function does not consume much energy.

Thanks for this. On a shoot I did a few weeks back where it was pretty cold, both certainly took a while to 'warm' up.

826 Raw Posted at 1-12 02:47
Thanks for this. On a shoot I did a few weeks back where it was pretty cold, both certainly took a while to 'warm' up.

To avoid this, batteries must always be stored and transported above 15°C.

LV_Forestry Posted at 1-12 03:03
To avoid this, batteries must always be stored and transported above 15°C.

Agreed, and I knew this. But it has still happened a few times. TBH, since the last update, which I thought was great, well for me and what we do.