Powering Starlink on the go with Tesla Model 3

I’ve had my Tesla Model 3 for more than a year now. It has been an absolute pleasure so far and I would not trade it for anything else at any price including Tesla’s other offerings (yes, talking about S Plaid). Model 3 just has the most beautiful exterior of any other car. OK, let’s stop here because I can go on forever. But not without a photo of Tin Can:

Tesla Model 3

“Tin Can” is a reference to Major Tom’s spaceship.

I live in the city and have a fixed broadband and 5G around but being the tech head that I am, I had to sign up for a Starlink service. I actually thought of uses, mostly for when travelling. I put down my deposit in February and received my dish two month ago. I knew when I signed up that I would need to make it work with my car and while I waited, I crunched some numbers, with the assurance that should I determine it won’t be feasible to run Starlink from the car, I can simply cancel my order.

Model 3 can output 12A continuously on its accessory outlet (aka cigarette lighter port). With a nominal voltage of 12.7V, that’s 150W of continuous power, or 140W when taking into account the regulation losses when stepped up to 56V needed by Starlink. Starlink’s own power supply has a total maximum output of 180W. That doesn’t look too good until one digs a bit deeper through forums and learns that Starlink’s user terminal, called Dishy McFaltface, generates heat either as a result of higher transmit power, or specicially to deal with cold weather and snow. That’s where half of that 180W seems to go into. As luck has it, I live in a warm climate so it’s unlikely that mine would consume as much power. It’s also worth noting that with each firmware update, the dish’es consumption seems to drop ever futher down (40W reported by some users as of late).

TL;DR we need 90W of continuous power to run Dishy and have 140W available from the car.

Power consumption isn’t an issue because a base Model 3 has a 57KWh battery. Half of this capacity, taking into account a generous 20% in conversion losses and car’s own usage, can continuously power Dishy for 10 days. Unless I’m stranded somewhere, I’m most likely to charge the car at least once a week.

With the math out of the way, I had to figure out how to power Dishy from the car. First step was to get a DC-DC regulator that could take the 12.7V of the car and step it up to 56V at 2.5A (to cover the max the car can offer). The only product I found with a more than reasonable price was made by a Shenzhen based company called Daygreen Technology.

Daygreen DC-DC Switching Regulator

I put the regulator to some test, running it at its maximum rated output current for an hour and it held up quite well, only getting 18 degrees warmer, and running at a respectable 95% efficiency.

For the next part, it’s important to know that the Starlink’s stock power supply is a Power over Ethernet (PoE) injector with two ports, one which connects to the dish, and the other to the supplied Wireless router. That’s good and bad. Good in that it uses PoE standard and bad in that it’s running 180W over it!

Ethernet ports on the stock Starlink power supply unit

Setting up Starlink was the easiest Internet setup I have ever done. Everything was plugged in out of the box. It just needed to be plugged into the power!

Information label on the Starlink stock PSU

The highest power commercial product that didn’t cost as much as the entire Starlink terminal itself, was rated at 90W. Given the pricing and lack of confidence whether anything else would be able to power this beast, I decided to purchase a spare Starlink power supply for $120 AUD and try to re-use the low voltage part of the original one, Frankenstein style!

Bottom of the Starlink PSU PCB held in a jaw prior to cut

Word of warning: as with any other mains powered board, there can be capacitors charged at dangerously high voltages even when unplugged. An accidental touch can lead to death! Do NOT attempt this if you don’t know how to stay safe.

Above picture is the back side of Starlink’s power supply PCB with the black lines, marking where I would run my Dremel across, in order to cut the PCB into two halves: the high voltage side to the left, which I’d discard, and the low voltage side, which I would hook up to the DC-DC regulator.

Post cut of Starlink PSU PCB showing the top side

It went surprisingly smooth and I managed to do a test run, powering the dish with 56V applied to the board. Turns out, the low voltage board needs a second supply under 20V to run the chips which the 12V from the car conveniently covers.

While testing, I managed to short the output of one of the power FETs. That destroyed the FET and blew the capacitor next to it. After a bit of consideration, I decided to remove the FETs and short their input and output. The only reason for having the FETs is to protect devices that don’t understand PoE. In my case, I will only be using this to power Dishy. No FET means no heat and less energy loss too!

FETs replaced by wire on the top side of the Starlink PSU

A 3D printed case and some wiring later, led me to a half decent setup from the car’s outlet to the dish.

White 3D printed case for the Starlink PSU low voltage board

PSU, DC-DC regulator and the car plug all connected together

Oh, and one more thing. Dishy comes with a rather long cable that’s not detachable. The long cable makes sense for the main use case of permanent installation in a house environment. Not so much when you want to carry it around. So I cut the cable close to the dish, patched the end with an Ethernet plug and bought a weather sealed joiner to maintain the weatherproofness of the original cable.

Weatherproof Ethernet joiner with one half open showing the port

I recently went on a trip a few hundred KMs away from home and put the setup to the test. It worked flawlessly, but it did take a while for the outages to drop to a usable state. This is well documented and expected at the beta stage of the service.

A few final notes: