Shoes & Gear

Garmin (or any) GPS Charging While You Run

Garmin (or any) GPS Charging While You Run

“Charging On” – How I Took My Garmin To The Edge, And Beyond. By: Lane Gremillion

Ahhhh………The GPS reciever. Whether you like Garmin, Soleus, Nike, Polar, Suunto, or Timex, if you dig into a runner’s sacred “running drawer”, 9 out of 10 times, you will find one of these devices. I still hear talk of running “purists” who don’t use GPS, and instead, opt for a plain stopwatch or nothing at all, but that is not me. I will be the first to admit that I am a “tech junkie”. My weapon of choice is the Garmin 310XT, and I love it. In fact, I would say it is one of my most valuable pieces of running equipment, ranking a very close second to only my shoes. I remember my first GPS device. It was some triangular, European piece of crap, that you wore on your bicep and basically only kept track of your distance and time. Looking back now, it was the equivalent of living in the stone age, as far as GPS receivers go. After a little time, I graduated to the Garmin 305, which I loved, and after I laid my 305 out to pasture, I upgraded to the 310XT. Why do I like my GPS so much? I think it is two things: First, I enjoy the freedom it gives you when you run. Gone are the days of scouting out routes with the car odometer and marking mileage with mailboxes, unusually shaped trees and houses. With my Garmin in hand (or on wrist), all I have to do is head out the door and run. No need for a specific route or any pre-planning of that route. Secondly, I love the real time information. I am not one of those runners who has just one huge screen going, and then get the other info when I’m done. I have all four of my split screens running simultaneously. Time, Distance, Pace and the ever important Average Pace, which in my opinion is the most crucial informational screen I use. And of course, I have my other screens that I flip to to get info on my current lap, elevation, etc…. I am so hooked on my Garmin that I think that if I had to choose between it and my shorts, I’d probably go with the Garmin.

Now comes the problem at hand……….battery life. The Garmin 310XT has a battery life around 18 hours. Maybe 20 if it’s brand new. When you are running distances from 5Ks to marathons, and even 50 milers or 100Ks, this is usually enough power to survive the entirety of the race. However, unless your name is Scott Jurek, Tony Krupicka or Hal Koerner, chances are you will not have enough battery life to finish a 100 mile race or more. And as they say, “There lies the rub.” So, like many other runners, I experimented with different techniques to save power and extend battery life, such as turning off the back light and all the bells and whistles. Anything to save a little power for later. Now these measures are small and in the grand scheme of things, probably don’t give you that much more battery life, but at least it makes you feel like you are contributing to the cause. In fact, the most I had ever gotten out of my 310XT was at the 2011 Rocky Raccoon 100 Miler, where I managed to get 18 hrs and 80 miles in a single charge. That being said, for the last 2 hrs or so, I could not get any information on my screens, only a low battery message; but the information was being stored. I ended up finishing my final lap there with a 305 I had borrowed from a friend. In fact, for my 4th 20 mile lap, I wore both my 310XT and my friend’s 305. One on each arm, because I didn’t want to lose touch with my pace and mileage. It was a crude and elementary way to log 100 miles, but it worked. So, all that being said, the question now on the table is, “How to squeeze more juice out of your battery?”

If you’ve ever seen the Robin Williams movie, Dead Poet’s Society, you will remember the scene where he makes the students stand on his desk in the classroom and tells them, “Just when you think you know something, you must look at it from another angle.” (On a side note, I bet you’ve never seen Robin Williams referenced in a running blog. HA!!!!) Well, that is what I had to do when searching for a way to get more battery life out of my Garmin. And what I learned when I stood on that proverbial desk is that it is not about squeezing more juice out of your battery. It is about putting more juice into your battery. How did I come to this conclusion??? I saw a post on Facebook one day of someone talking about a mobile USB charger for charging their phone when they went camping. With that information in hand, I had the little light bulb pop up on top of my head. If you can use a mobile USB charger to charge your cell phone, then why not use it to charge your Garmin? The idea didn’t have to sit long before I went to Amazon.com and found the Trent Heavy Duty External Battery Pack. It sold for $39.95, which was a small price to pay if this idea were to work.

Trent Heavy Duty External Battery Pack

Trent Heavy Duty External Battery Pack

When it arrived, I charged it up and took it out for a test run. To my surprise, it worked very well. I rigged it up to my gear (pictures further down the blog.) and charged my Garmin on the run. The only downside is that while you are charging, you cannot view the information on your screen. All you get is the percentage charged and the time of day. It seems to take minimal power to charge the Garmin, so I would expect that you could get around 8 charges out of one fully charged battery pack. Now that I had even more technology to pack on runs, it was time for the ultimate test. I was running Cactus Rose 100 on October 27, 2012 and I wanted to attempt to charge on the run and keep my Garmin going for the entire race; something I had never been able to do before.


Battery pack with Garmin charger attached.

When race day came, I had my battery pack fully charged and I placed it in my drop box at the 45 mile point. I was pretty sure I wouldn’t need it until 50 miles or beyond, but because of the rugged terrain of Cactus Rose, I dropped it early to be safe. When I got to mile 45, I had enough battery life to get to the 50 mile point, so I just packed it with me to the start/finish area. When I crossed the 50 mile point in 12 hrs, 5 mins I still had 38% battery remaining, but I went ahead and got ready to charge. I put the battery pack in a Ziploc bag and placed it in my Camelbak. I then ran the charging cord through my shirt and out of my sleeve and connected it to my watch. The most important part to this set-up was the cheapest. I used two wrist bands to hold the cord in place, so I wouldn’t accidentally bump it and disconnect it while charging. I was all set and charging as I set out for my third lap. The plan worked flawlessly and I was re-charged to 100% battery life in about 1 hr 45 mins. After I was charged, I continued to run with the battery pack in my camel back, just in case I would need to top it off again. I’m glad I did because my second half of this race was considerably slower than the first and although I probably could have made it the whole second half without another re-charge, I opted to charge up again around mile 85, just to be safe.

Charging set-up. Wrist bands hold everything firmly in place. Not yet connected to Garmin.

Charging mode.



This is all you will see on your screen while charging on the run. If you remove the charger from the watch to check your current status, the pack automatically shuts off, so be prepared to turn it back on again.

When you initially begin charging, the pack tells you the level of charge in the pack itself. Either “Full”, “High”, “Med” or “Low”. When you are actually charging your device, the “Use” light will be on. This way you know you have a good connection and are charging.



After about 10 seconds, the battery level will disapppear and only the “Use” light will be on. As long as that is on, you are charging.


According to my Garmin, each 25 mile lap was actually 25.4 miles, so I knew I would have the opportunity to take it beyond 99.9 miles. And that was the big question for me. What would happen after 99.9 miles? Would it flip back to 0.00? Would it have a Y2K style meltdown? I just didn’t know, and I didn’t know anyone else who knew either. So when the moment of truth came and I hit that magic number of 99.9, I watched with anticipation as my Garmin ticked closer to 100. 99.98, 99.99, and then the moment of truth. My watch crossed the 100 mile barrier and kept on counting. The mileage read 100 and counting. I was happy. My experiment was a success.

My Garmin post-race.

When I crossed the finish line, according to my Garmin, I had logged 101.7 miles and 29 hrs, 32 mins of constant run time. The cool part is, the watch could have gone many hundreds of miles more, even though I couldn’t.

So now I have a winning formula for any future 100 mile races, and I will continue my “charging on the run” strategy. Never again will I worry about when my battery will die during a race. Now all I have to do is hook up and charge on.



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3 Responses

  1. David P. says:

    Thanks for the awesome idea. I assume that the Garmin kept recording even while you were recharging. I have a Trent external battery, but didn’t think to try this. I will try it out now and use it in my upcoming Zion 100 if it works. Thanks.

  2. Lane says:

    I have been running with the same Garmin for 4 years, and have only charged it on the run for the one 100 miler that I wrote this blog on. As far as I can tell the battery life is the same.

  3. AKRay says:

    The Garmin manual warns against charging when the terminals have moisture on them. Do you think that the perspiration and salts on your skin while running and charging would be detrimental to the the Garmins battery?

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