In the aftermath of our cyclone here, I got dragged out for a bit of media comment and, downstream, a few questions came up on dishy power use. Here's what I know and can glean - comments welcome:

• Starlink's own specs say 50-75 W "Average Power Usage": https://www.starlink.com/specifications. But that's average, not peak, and peak is what matters when people start recommending that Starlink could be run out of a small inverter and a car battery in a disaster.
  
• Small inverters usually come with cigarette lighter cables, and cigarette lighter sockets are typically fused with 8 or 10 A fuses. That puts maximum safe power outputs in the 96W to 130-something W range depending on battery voltage.
  
• Our lab's "RV" subscription rectangular dishy & router regularly clocks in at around 80-100 W, and I've seen it go as high as 108 W on one occasion. I've also seen it go as low as 30 W for the first time last night.
  
• I have a user report from an older round dishy owner having seen up to 200 W on occasion.
  
• Assuming conservatively 90% inverter efficiency, that could mean up to ~120W and maybe more for the rectangular version and over 220 W for the circular one.
  
• If dishy goes over cigarette lighter fuse capacity, people may lose their ability to charge phones from their car - also a critical capability in a disaster.
• Not everyone takes kindly to the suggestion that advising inverter + car battery use could potentially be counterproductive.
  
• So, what's the peak power use you have seen on your version of dishy?
• It appears that the current mode of operation here is that dishy uses several satellites in parallel if these can all see a gateway and have capacity to carry traffic.
  
• So for us in urban Auckland with few Starlink users in the cell and three gateways in the vicinity, our dishy is spoiled for choice and usually gets to use maybe three or more satellites at once. That takes a corresponding amount of power but also means great data rates a lot of the time.
  
• For a rural user with more Starlink users in the cell and further away from gateways, the satellites that the cell can see and that  can also see a gateway may be fewer in number. This means dishy only gets to talk to maybe one or two birds at a time and so uses a lot less power, and you get more average data rates there.
• If this is so, then it begs a question:
• If Starlink could cap the number of satellites dishy can use in an emergency area, they would be able to keep your fuse intact. Should they aim for that, even if it means that you might see lower data rates in a situation when many people depend on one unit?

Starlink is currently being touted as THE comms solution for emergencies as large swathes of NZ's northern and eastern North Island remain without terrestrial or mobile Internet coverage after cyclone Gabrielle. This is the outage map of one of the larger mobile phone providers just for these areas:

Most of these are due to power outages to sites, but there are quite a few backhaul cable issues as well.

One of the biggest problems is that electronic payment systems don't work without Internet. In our largely cashless society, this is leading to situations where emergency services can't refuel their vehicles because their fuel cards won't work, supermarkets and other stores can't sell anything because customers have no means of paying, and the air force is flying in hard cash in order to help the locals buy food.

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Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel@auckland.ac.nz 
http://www.cs.auckland.ac.nz/~ulrich/
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