Unfortunately your wrong in response to batteries are not effected by the cold, to which they are and will continue to be greatly effected by cold weather. Sometimes you will see your battery life cut in half in cold weather....but that's more so your not able to fully utilize the battery capacity. You don't really lose charge, just can't take advantage of the full charge
Anker released protect your batteries in the cold
Best practise is to keep the pack warm while trying to charge devices, keep it close to the body or wrapped in a wool socks.