ways to save power

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i tested how long does my holux m1200e lasts before the battery dies. the result is a little bit over 11 hours while manufacturer mentions (up to) 16 hours. now i believe i could get close to this number if i'd choose logging every 5 seconds instead of 1 but this is not what i'd want to do. instead i was thinking.. is there a way how to turn off bluetooth? i barely use it since i have a secondary bluetooth gps module and i want holux to be a logging-only device.

if there's not such an option, will turning off the nmea sentences save some power?

thank you,


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Hi I do not know the m1200e,


I do not know the m1200e, so I'll answer based on my knowledge of other devices.

  • Until now all devices have their bluetooth on or off based on a physical switch setting and I am not aware of a SW based control;
  • Even is bluetooth is on, as long as there is no connection, the NMEA sentence settings should not have an influence on consumption because without a connection, there is nothing to emit to;
  • Reducing the NMEA sentences surely has some influence on consumption during connection.  You can remove sentences or reduce their emission frequency.  If all regular sentence are at 0 I observed that at least on the previous MTK chipsets bluetooth communication is no longer possible.  (The debug sentence is not a regular sentence for instance).  Therefore, keep at least one 'alive' (like ZDA which is a short sentence);
  • Power consumption is also determined by the GPS activity itself.
    - When there is no fix, the device must search for satellites which requires more computing power.  Some GPS chips even have an aggressive and a low power search mode.  So make sure that your GPS locks as fast as possible and as long as possible.  AGPS could help in some conditions.
    - Having the device on indoors means that you'll have higher consumption.
    - Having a bad reception means that the antenna signal needs more amplification and hence more consumption.  Make sure you point the antenna towards the sky.
    - A higher fix frequency means more computing and more consumption.  You could set the fix at 0.5Hz, but the best is to not go lower than 1Hz;
    - I imagine that SBAS/WAAS/EGNOS computations also require more computing power.  I am not convinced that that really improves accuracy - even if it does standard accuracy is sufficient for me.  Turn SBAS off.
  • Writing to flash memory costs energy.  Logging lest often and less data also helps reduce consumption.  In stead of logging every second, think about logging every 5 or 10 meters.  Do you really need RCR and VALID?  The HDOP field gives you a pretty good indication about precision already.

And finally, keep your battery 'healthy'.  Do not charge it frequently, i.e. after short discharges, do not store for an extended period when it is 'fully charged', store it at a reasonable temperature too.