battery charging on 405cx

I know from experience that the battery life of the garmin405CX isn't brilliant. I usually charge mine twice a week. What I am wondering is- am I doing any long term damage by charging the battery before it is completely flat?( I know with laptops- the lifespan improves if you only charge it when the battery is low)

Tonight I have 34% battery left; how long would this last for a run? I plan to do 10m tomorrow at 9:30 pace. Is 34% enough, or should I charge it tonight. I have had the experience of the watch getting the "low battery" signal and then going dead during a long run- which I want to avoid 

apart from this i think it is a great bit of kit.


  • Chris.52Chris.52 ✭✭✭
    I am told that this type of battery can be charged as much or as little as you like as often as you like without damaging it. This advice comes from someone who never tires of explaining how to treat laptop & mobile batteriesto get the best possible life from them.
  • great Chris: thanks for thatimage
  • As far as I can tell you most modern batteries don't like deep discharge that often, but also really HATE overcharging. So charge it after you run, but take it off charge once it is 'cooked'.  Deep discharge infrequently, but there is some value to doing it to keep capacity as high as possible...
  • Been topping my 405 up for the last 2 years, battery life is still around the same as when I brought it.

  • This is useful, thanks folks!  I just got a 405 and am a little surprised by how poor the battery life is.
  • Odd I think the 405 cx is good , its sound for a few hours training and being worn as a watch on three day biz trips , cant fault it.
  • My wife's 405cx battery completely failed during the snowdonia marathon and hasnt worked since.  Useless for a 2 year old watch.  Mine has just done the same thing.  Utterly unreliable.

  • I must admit I've never used my 405 as a normal watch, so haven't thought much about its battery performance outside of a run. 

    When it was new it would just about manage a day cycling- about 8 hours with 6 or so hours actually riding. Now I get nervous over 4 or so hours of cycling. But that is loads for running. 

    I do charge it every day though.

  • DLDL ✭✭✭

    Idiot question please. My 405 only stays charged for a little over 3 hours now - annoying when it lost the end of my one and only marathon. Is there any way of replacing the battery or do I need to contact Garmin?

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