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Home » Cycling » Garmin, GPS Satellites, GLONASS, GALILEO, And Why Your Garmin is Sucking Power… The Quick and Easy Explanation (And What to Do About It).

Garmin, GPS Satellites, GLONASS, GALILEO, And Why Your Garmin is Sucking Power… The Quick and Easy Explanation (And What to Do About It).


I’ve got a Garmin Edge 520 Plus and I just bought a 530 Plus for my wife. Whilst she was setting her Garmin up, she came to a screen that offered to use “GPS”, GPS + GLONASS, or GPS + GALILEO. Obviously, being the all-knowing velorishi of the household, my asked me what all of that meant. I tried to make my blank stare look less like a blank stare. I was stuck. And so, with all of the confidence in the world, I let the cat out of the bag. “I have no idea”.

So, I started looking through my Garmin and sure enough, I had “GPS” and GPS+GLONASS options. I clicked on the GPS only option for both of my outdoor cycling profiles. My wife read that using both eats up battery life a little faster.

Now, this is interesting. Some time last year I noticed that my battery life was draining faster than normal. It was an all of a sudden thing. When my 520 should have lasted seven hours, I was getting six. I put it to the battery getting older, though I have taken special care to discharge and recharge it properly so it didn’t develop a memory.

Now it all makes sense.

The GPS + GLONASS option is automatically selected, so I had to go through my Activity Settings and change it to GPS only so I can get back to my seven hours of battery life… and then I had to investigate exactly what I’d done to make sure I didn’t mess up my GPS device!

So here’s the quick of it: GLONASS is the Russian equivalent of GPS. GPS has 31 satellite in use and GLONASS 23. The idea is, for accurate location data, you need three satellites at any given moment. You need four for accurate elevation readings. Having GLONASS or GALILEO enabled simply gives your device more satellites to choose from so you have the necessary number more frequently.

How necessary are the three? Well, as it turns out, apparently not really. According to this page, if you’re in the mountains or in a city where buildings can block a GPS signal, having the extra satellites can be useful. Otherwise, it’s kind of a waste. Well, you just have to pick your poison, I guess. Extra-accurate GPS, or battery life. For me, it’s absolutely battery – though I’ll be switching that when my wife and I head to Georgia later this summer. And, if you want to know how to do that, click (here).


3 Comments

  1. I use the “GPS + GLONASS” option so that both US and Russian covert authorities can accurately track my location…

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