Thursday, 2 May 2013

Extending the battery life of a Garmin 405

I love my garmin 405 running watch and use it on every single run I go on, recording the run, timing and route details as I plod round and then, later, uploading them to garmin connect and strava on the internet, from where I can pour over all my running stats to my simple running geek's heart's content. The watch is getting a wee bit battered around the edges but still works perfectly and, nowadays, such is my level of garmin 405 expertise ☺, I even get on with the ******* (expletive deleted) bezel, the rim of the watch that is touch used for changing settings!!! (Remember on a run: Always. Lock. The. Fricking. Bezel!!!).

Since getting the watch the Christmas before last there isn't a run done that I haven't recorded.... apart from that is all the really long ones!!!!! This is the fly in the ointment - if you want to do a really epic run, just the sort of run that you'd particularly want to record, well, with the garmin 405, you're limited by its battery life. There are other watches that give you longer lasting batteries of course but some of those look like mini computers strapped to your arm and others cost an arm and a leg. And even then these behemoth running watches might plot your route with reduced gps fixes (say one per minute rather than one per second) so as to extend the battery life, but give you a much blockier route profile in the process. 

The battery within the garmin 405 only lasts 7 to 8 hours before it needs recharging (on my watch anyway) and I know that others with the same watch may even get even less battery time than that. So whats the solution? Well up until now I didn't have one but I have now 'perfected' a fantastic Heath Robinson contraption that allows me to recharge my garmin 405 on the hoof, with the run details still being recorded. Its called a Duracell USB recharger (£25 from Amazon) and I can hold it in my hand, gaffer tape it to my arm (this version still needs a bit of beta testing) or, if worse came to worse (really bad weather for example) just place the watch in my backpack or bumbag while its recharging.

I used this brilliantly at the Fellsman at the weekend and, when I got to Stonehouse (about 6.5 hours in), I just strapped on the battery charger for a couple of hours until the watch was fully charged again. Later again having been running for 15 hours I strapped it on again just to get me to the finish. The watch finished the run on about half battery and the charger still had two of its three battery lights flashing at the end. I'm not sure how long I could go with this but, for sure, I know it will last 16 hours 52 minutes and it will almost certainly last 20 hours I think. Hmmm... for a Bob Graham I might need a spare charger just in case☺

All you need.......

Dragon's Den here I come (note the mud from the weekend still on my garmin USB lead clip)

How to hold it while running - it also works just as well in the left hand!


  1. now that is really clever....i have also been frustrated by the short battery life on the garmin 405, in my case its about 40mins at times due to age of watch presumably. Will have to look into your solution.

  2. Stolly followed this from the FRA thread and got the charger, well impressed and solved me a problem that i wouldn't have sussed on my own, cheers

    1. Thanks Gary. Brilliant isn't it and you only look slightly stupid holding the battery with the charger cable dangling :)

    2. Hi guys - does the GPS & activity log still work whilst the watch is on charge ?

  3. gps can still connect while holding the battery with the charger cable dangling ??

  4. I just ran my first ever 50K Ultra Trail Marathon this weekend and my Garmin died at mile 27! I was so disappointed that I did not get the entire race recorded and I just stumbled upon your blog, just hooked up my 405 to my portal MyCharge battery and it is charing it up quick like! I wish I would have known/figured this out earlier. Is it able to continue to record your run/gps tracking and charge at the same time? I assume yes but wanted to ask. Thanks

  5. Brilliant tip :) I found your blog the day before the hardmoors 30 and managed to recharge my 405 on the go so it recorded the whole run- I guess this blog is dead now but just in case you see the comments I wanted to say THANKS!

  6. This looks to be a great solution. I just ordered one ahead of my 50 and 100 milers this year. The USB is down to $10 on Amazon - way cheaper than going up to a Fenix 5 (which will happen eventually).

    I also loved your review on the Inov8 Mudclaw race looks as though it will be particularly muddy this weekend and you gave me the confidence to pull the trigger.

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