Looking at tracker 20 on Fjalls we can see it settling into winter – running on battery:

now that average temperatures are below zero the solar charging of the battery is very rare (to save the battery from charging when too cold). It also skipped a few readings in january – which is unusual behaviour – possibly due to its base station misbehaving?

however the Fjalls base stays quite warm (especially in the sun!) so is solar charging OK.

we can see from plotting lat/long that it started to have more outlier readings recently (bottom right). There is usually a very consistent plot of points.

Its altitude jumped upwards in mid december! we can also see the drop due to melting before september and the gradual rise during autumn.