Mine should be here sometime today... YEA!
The SB-1 was a fun build and looking to enjoy the SB-II.
As soon as I read Garibaldi I knew cold was the issue.
The big issue is the cold. Radios don't like it and batteries of any type rebel.
Keeping the batteries warm or warming them works. Even the dead appearing
ones if fully charge will come right back once warm. So capacity is not the issue
but managing temperature. To that cylinder cells (AA, 18650) are best choice
and thermal bag with a hand warmer I keep them on the body and that makes
a huge difference. Seems the threshold for batteries going to sleep is in the
low 40s (F) getting them to mid 50s or warmer seems to make them happier.
The upside with cold batteries is they are not dead just cold and the self discharge
when cold is not an issue. So warm them and they are 100% again.
Keeping a 3S or 4S pack inside my coat is not problem. Even my larger 3S4P
(11AH) for the FT817 only weighs under 3 pounds and fits in pants or coat
The radio needs to be kept warm as sharp temperature transitions can be hard
on components internally and soldering in general. Plastics tend to shatter
when extremely cold (below about 20F). LCD displays many quit working
when that cold and colder can destroy them. The sun can be helpful so a
black outside is a plus.