I’m lucky enough to own a Garmin 910XT GPS watch. It’s fantastic as it gives me insight into how hard I’ve trained, where I’ve trained and then neatly bundles all the data into a website for me to review later on. Lovely.

However, the battery life, even on the 910XT which is designed for long endurance events, isn’t able to provide enough charge for a long distance ultra-marathon. For a 50 miler, the watch is fine. But for a recent 86 mile event, that took 19.5 hours, I was glad I’d used a USB battery back at the halfway point to recharge.

What USB charger do I use?

I wanted a tough water and knock proof battery that wasn’t too heavy, could hold a good deal of power for not only my watch but potentially my phone and be easy to operate in the dark (and whilst I’m tired).
I settled on the EasyACC 9000mAh charger from Amazon.co.uk.

It was a bit of a bargain at £26.99 and came with cheap compass and carabiner (which I junked both of). as it’s USB based, you can charge any USB based device from it as well; such as my iPhone and iPad. Perfect for holidays and long days out.

What I did to keep my Garmin alive in an ultra-marathon

I had a half-way point that offered a drop-bag and in there I stashed the USB charger and the Garmin USB charging cable.
  • When I entered the check-point, I simply took off my watch (it auto-pauses)
  • I then plugged in the charger cable into the pack
  • Turned the pack on
  • Connected the charging cable to the Garmin as I would normally do at home

In 20 minutes, which was the total time the device was left unattended to charge, the Garmin had changed from 61% to 100%. Sure it could probably have done more in that time too.

  • I then unplugged the charger
  • Stowed the cable and charger back in my drop-bag
  • Left the check-point with 100% charge, good for another 10 hours at least
It worked and I finished a 19.5 hour event with plenty of spare battery too and most importantly all of my Garmin data intact in one Garmin file.
You can even take a look at the Garmin file for the 86 mile Ridgeway Challenge yourself.

Keeping the Garmin alive for a 100 mile+ ultra-marathon

Charging the Garmin on the go means
you won’t be able to view the display
What’s particularly cool about the Garmin and USB charger combo, is that you could charge the Garmin on the move.
I tried it a few times to prove that it works and it was flawless. Here’s what you’d have to do.
  • Turn on the Garmin and track satellites as normal
  • Start the Garmin clock and start running

Then when you feel you need to recharge the battery, do the following:

  • Connect the charging cable to the USB charger
  • Loosen the watch on your wrist so that you can slip the charger clip in behind
  • Turn the USB charger on
  • Attach the charger cable to the watch
  • The watch display will go off at this point and show the battery percentage instead
    • Fortunately, all data points will continue to work, such as
      • Time
      • Satellite tracking
      • HR
      • Etc. will all work fine
  • When your charge is complete or you want to see the display again, unclip the charging cable from the watch

Take care not to pull the cable from either the charger or the Garmin. I secured the cable with a wrist band and stowed the USB pack in my running pack.

The alternative to charging your Garmin is investing in another Garmin

Garmin Fenix 2 GPS watch

The Fenix 2 apparently is built for real endurance adventures and adventure racing. The blurb says 50 hours of battery life, which is impressive, but you will lose GPS accuracy.

Or you could get a Fenix 2 and a USB charger.