STAR-Tank Phased Coherent Radar Fuel Tank Sensor

Battery-operated phased-coherent radar fuel-tank level sensor, Victron/Cerbo compatible.

About this product

Fuel level on your Victron GX with no sender and no wiring to run. The sensor mounts on top of the tank, runs 3-5 years on its own battery, and streams level, temperature and battery voltage straight to a Cerbo or Ekrano GX over Bluetooth.

Fuel behaves differently to water under radar, so the fuel sensor measures differently. Rather than reading a reflection off the liquid surface, it uses time of flight: the signal travels down through the fuel, reflects off a metal plate at the bottom of the tank and returns. From that travel time the system derives reference values for empty and full, and the GX turns those into the percentage you actually read.

Two consequences worth knowing before you install. The metal plate and the sensor both need to be centred, and the larger the plate the stronger the return — how large depends on the distance between the sensor and the tank bottom. And the raw number on the Cerbo is a reference value, not a depth: it is labelled "cm", but it is not centimetres.

No sender, no float — the level is timed

The fuel algorithm is not the water algorithm: the signal passes down through the fuel layer, reflects off a metal plate at the bottom of the tank and comes back, and the round trip is what the level is derived from. Centre the plate under the sensor, and size it for the depth of the tank — the further the sensor is from the bottom, the larger the plate needs to be for a clean reflection.

Two readings, empty and full

Calibration is a two-point exercise on the GX. With the tank empty or nearly empty, put the sensor into sleep mode and wake it so it re-reads its surroundings, then record the sensor value on the Cerbo as the empty figure. Fill the tank, read it again, and record that as full. Sleeping and waking it is the part people skip — it is what makes the sensor re-detect its environment and it is where the accuracy comes from.

Nothing goes inside the tank

On polyethylene, plastic or fibreglass the radar reads straight through the tank wall, so nothing is cut and nothing is drilled: the base plate bonds to the top of the tank, and once cured the sensor screws onto it. Metal tanks need a clear view of the liquid, so the base carries an SAE 5-bolt pattern — the industry-standard hole set — sealed with gas sealing tape.

One button, and it tunes itself

A tank is a box full of reflections. Press and hold the black button for about ten seconds and the sensor runs a startup routine that picks the dominant line-of-sight return out of that clutter, then locks to it so it is not re-solving the problem on every reading. The ring LED holds solid red while it works and turns solid green when it is done.

Measured in years, not months

There is no wiring to run because there is no wire. The sensor samples every 60 seconds, which is what buys the battery life: about five years where the tank averages around half full, falling toward three where it habitually sits low. A short press of the button steps reporting up to every 10 seconds for 10 minutes while you commission it, then it drops back on its own.

It arrives in Venus OS already knowing what it is

STAR-Tank support is built into Venus OS, so a GX device picks the sensor up in the Bluetooth sensors menu and lists it — there is no GX Tank 140 and no sender wiring in between. It reports three values, not one: liquid level, tank temperature, and its own battery voltage, so the sensor tells you when it is getting tired. The temperature value can drive the GX temperature relay to run a tank heater or stirrer.

Works with

  • Victron GX (Cerbo GX, Ekrano GX) — Bluetooth advertising, native Venus OS support
  • Marine MFD — Via the STAR-Tank to MFD interface kit
  • STAR-Switch Custom — Logic blocks can act on tank level
  • Phones, tablets, third-party displays — Not supported

Specification

Measurement

Technology
Phased coherent radar
Method
Time of flight to a bottom plate
Reading
Calibrated reference value
Liquids
Fuel
Dead band
30mm from the sensor base
Measuring range
Set during setup, on site

Power

Wiring
None — internal battery
Expected battery life
3-5 years
Reporting interval
60 s (10 s for 10 min at setup)

Communications

Pairs with
Direct to Victron GX
Radio
Bluetooth 5.3, advertising output only
Venus OS
Victron GX / Venus OS only
Reports
Level, temperature, battery voltage

Construction

Housing
Billet-machined aluminium
Mounting
Bond-on base plate, or SAE 5-bolt on metal tanks

Approvals and warranty

Approvals
FCC (USA), CE, UKCA
EU declaration
RED 2014/53/EU art. 3.1 and 3.2
Warranty
5 years on non-metallic tanks, excluding the battery
Warranty, metal tanks
1 year (SAE 5-bolt installation)

Questions

Why does the Cerbo show a value in "cm" that is not the tank depth?

Because it is a reference value, not a measurement in centimetres. The fuel sensor derives level from the signal's round-trip time to a plate at the bottom of the tank, and the GX converts that against your calibrated empty and full figures into a percentage. The underlying number is labelled "cm" by the display, but it should not be read as a depth.

Do I really need the metal plate?

Yes. The fuel measurement is a reflection off that plate, so without it there is nothing to time the signal against. Centre it under the sensor, and size it up as the distance between the sensor and the tank bottom increases.

Do I need to tell you my tank depth before I order?

No. The measuring range is set during setup once the sensor arrives, not fixed at the factory and not chosen when you order, so there is nothing to confirm with us first. If you want a second opinion on a deep or unusual tank we are happy to look, but it is not a step in buying one.

Do I still need a GX Tank 140?

No. STAR-Tank talks to the GX device directly over Bluetooth, so there is no tank-sender input to wire and no Tank 140 in the middle.

Can I read it on my phone?

No. The radio is advertising-output only and is intended for a Victron GX device. You read the tank on the GX, on the Victron touch display, or remotely through VRM.

What is the dead band?

The first 30mm below the base of the sensor cannot be measured. The tank wall counts toward that figure rather than adding to it — on a 12mm fibreglass tank the dead band ends about 18mm below the inside top of the tank.

Will it work on a metal tank?

Yes, but the radar cannot see through steel or aluminium, so a hole is cut and the sensor mounts to the SAE 5-bolt pattern built into its base, sealed with gas sealing tape. Note the warranty differs for that installation: 1 year, against 5 years excluding the battery for an above-tank non-metallic install.

SKU
RDR10208002-FUEL
Category
STAR Digital Switching
Price
$345.46 AUD inc. GST
Availability
In stock

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