Ok, now I have an explaination for the poor charge, I think I also have an explanation for TeslaFi unrecorded journey/charge
I had a second instance of this but seeing it happen there and then rather than retrospectively having to remember the circumstances, I believe this happened. I suspect I have a wrong setting or there is a shortfall in Api/TeslaFi logging capabilities.
Scenario. About 30 mins prior to my wife leaving for work, I decided to experiment with pre heating the car. So, used app to set climate, which would have woken it. This transition is recorded in TeslaFi at 07:26 as car transitioned from sleep to park/idle.
The idle is then reported in TeslaFi as finishing at 08:13. However the car would have started its journey at just prior to 08:00 - I suspect, some point between 07:57 and 08:00 but don't hold me to those exact timings. So whilst TeslaFi says that its a drive from Home to Work, as confirmed from start and endpoint map, it incorrectly records that drive as 08:13 - 08:24 and the GPS tracking truncated the first approx 10 mins of the journey.
So, what did TeslaFi say was happening?
From TeslaFi 60 second drive logs, 07:57 to 08:12, in other words, the time I believe car departed to point TeslaFi said car was driving, TeslaFi reports "TeslaFi Sleep Mode Sleep Attempt", followed by 14 minutes of "Trying To Sleep" followed by "Vehicle Did Not Fall Asleep" and eventually at 08:13 "Idling->Driving".
So I believe that TeslaFi started to allow the car to sleep by not polling the car. This critically coincided with the start of the journey. It then failed for whatever reason, to realise that the car was driving during the first period of the drive.
During this period, I am not sure if TeslaFi should have been polling the Tesla Servers (but not the car to avoid waking the car) or whether there is no return from the TeslaApi that TeslaFi should be able to use to detect that car is driving without waking it if it isn't.
Or I have a setting wrong - unfortunately I cannot remember the sleep setting I changed 4 weeks back.
Or there is some reason why TeslaFi should have caught the drive earlier, but didn't.
Otherwise I am delighted with TeslaFi and I will be today extending my trial to a full years subscription and hopefully longer if the few people that used my referral code also become subscribers.