mini BT, SunVario or FANET Vario: which one to buy

All three instruments use the same barometric sensor, resolve the same ±2 cm, speak to the same apps over Bluetooth LE, and update their firmware from the browser. Nothing in the list below is a cheaper sensor or a worse beep. What differs is what the instrument does besides beeping — and that is what should decide it.

First question: do you want other pilots to see you?

If yes, the answer is the FANET Vario, and the rest of this page is academic. It broadcasts your position over FANET — the long-range radio network that ground stations and other pilots’ instruments listen to — while beeping like any of the others. Nothing else in the line does this, so there is no trade-off to weigh: either you want to be visible on the network or you don’t.

Two honest notes. It has no GPS of its own; it takes the position from your phone through the app, so the phone has to be along for tracking to work. And it is a bigger instrument — 29 g and 92 mm long against 9 g of a coin-sized one — because a LoRa antenna and a real battery need room.

If being seen isn’t what you’re after, the choice is between the other two, and it is genuinely close.

mini BT or SunVario

Ten euros apart, both around 9 g, the same sensor. Three things separate them, and buttons and features are not among them.

The SunVario is louder. Both instruments drive the same kind of piezo through the same kind of charge pump, and the amplitude that pump produces is a multiple of its supply voltage. The SunVario feeds it from a charged capacitor at about 3.7 V; the mini BT from a coin cell that starts at 3.0 V and only sags from there. In wind, with a helmet on, that is the difference between hearing the first beep of a weak climb and missing it. To be fair in the other direction: near the bottom of its window, at 2.7 V, the SunVario is the quieter of the two.

The mini BT is the one that has been proven. It is the instrument most of our pilots fly, it has been in the air for years, and its behaviour holds no surprises. A new design is a promise; this one is a track record. If that matters more to you than anything below, buy it and stop reading.

In the cold, the mini BT is simpler; the SunVario wants a pocket. A CR2032 is good down to about −20 °C — the honest figure, not the datasheet one. From roughly −10 °C the cell’s internal resistance has risen enough that it can no longer deliver the peak current the buzzer asks for, so you turn the volume down and fly quieter.

The SunVario’s capacitor discharges down to −20 °C too, so the instrument does work in the cold. What it must not do is charge there: the cell is specified for charging only above 0 °C, and this one charges itself from the panel whenever there is light on it. That is where the −5 °C figure on the spec sheet comes from — not from the instrument dying at −6. The winter answer is simply to keep it in an inside pocket instead of out on the cockpit, and take it out warm when you launch. Expect less of it than in summer: at −20 °C a lithium-ion capacitor holds around 45 % of its capacity and its internal resistance is ten times higher, so the extra loudness that is its summer advantage is not what you get in January.

The SunVario forgives being forgotten. Here is the mini BT’s real-world catch, and it is the source of most “the battery died fast” reports we get: modern phones keep Bluetooth on permanently, so a mini BT you forgot to switch off stays connected and keeps working — and a 210 mAh coin cell doesn’t last long doing that. Nothing is broken; it was simply left on. Forget the SunVario in the same way and it costs you a minute on USB-C, because there is no cell to run flat and buy again.

About those four buttons

The mini BT has four buttons that a phone can see as a Bluetooth keyboard. In practice, almost nobody flies with them. Keyboard mode needs the instrument paired with the phone rather than just connected, and paired it stays awake and eats the cell — exactly the problem above. The lighter alternative, buttons delivered as a Bluetooth characteristic, is only read by our own app: xcTrack, SeeYou Navigator and FlySkyHy don’t support it. Treat the buttons as a bonus if you use our app, not as a reason to choose the instrument.

So:

• You want the louder instrument and never want to think about a battery again → SunVario.
• You fly through the winter and don’t want to think about it, or you simply want the model with years behind it → mini BT. Ten euros cheaper, and a spare cell in the pocket is a thirty-second repair anywhere.
• You want to be on the FANET network → FANET Vario, and neither of the above matters.

Side by side

	mini BT	SunVario	FANET Vario
Price	€89	€99	€149
Weight	9 g	9.8 g	29 g
Power	CR2032, replaceable	capacitor + solar panel	LiPo + solar panel
Loudness	reference	louder while charged	reference
Cold	to about −20 °C, quieter below −10	works to −20 °C, but charges only above 0 °C — pocket it	—
Sees other pilots	no	no	yes, over FANET
Sensitivity	±2 cm	±2 cm	±2 cm
Track record	years in the air	new in 2026	new in 2026

What we would not tell you

The SunVario is the newest, and newest is not automatically best. In a closed pocket with no light it runs about 8.5 hours with the phone connected — plenty for a day, but it is not the perpetual machine the panel suggests, and in winter it asks something of you — a pocket, and no charging in the frost. The mini BT is the simpler answer there: proven, cheaper, and fixable anywhere a coin cell is sold.

And if what you actually want is to be visible to other pilots, don’t buy the cheap one twice. Go to the FANET Vario first.