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Suunto Ambit External Battery Experiment – Test 01

The following is an experiment conducted with the Suunto Ambit to determine whether, through use of an external battery pack, the Ambit might be used to record high-detail logs (1sec intervals/1sec GPS fixes) longer than 16hours.


There are many outdoor activities that might benefit from a GPS/Navigation Device Such as the Suunto Ambit.  Some of these, such as Ultradistance Trail Running and Trekking/Hiking/Backpacking involving difficult navigation, would further benefit from the higher accuracy afforded by 1second GPS fixes and 1second recording intervals.  Unfortunately the Ambit provides a maximum of 16hours battery life when using these settings.  As an Ultra Runner looking for move into single-stage events lasting longer than 16hours (such as 100mile Ultra Marathons), finding a workable solution (i.e. not too bulky, too awkward, too sensitive to the weather, too fragile etc.) that offers high accuracy and a battery life in excess of 30 hours is important.

It is thought that a Suunto Ambit attached to an External Battery pack, charged through the Data/Charging Cable during recording, (like has been done with Garmin Devices) might be a workable option.


Test 01


1 x Suunto Ambit
1 x Sony external USB battery pack


1. turned on the watch to record at 1sec intervals
1a. unfortunately I couldn’t get a fix immediately (DXB Airport) and got one approx 7hours later (KUL Airport).
3. let it run for approx 7hours and then plug in the battery pack.
4. let it run for an hour and remove the battery pack
5. let it run for another 7 hours and reconnect the battery pack before going to sleep
6. turn it off.

GPX/KML files available here (click the respective file type)


1. The Log time was almost 29 hours
2. The battery life was still at 85%
3. approx 90,000 data points were recorded
4. The first GPS fix was at 6:43:53 the last at about 28hrs(corrected)
5. while record time was 1sec/1sec, GPS fixes were few and far between due to the big metal cylinder surrounding me and then entering a very dense house.


1. The watch will record while charging via a portable usb charger
2. There is certainly the capacity with this setup to go well beyond the purported max time of 16hrs with 1sec/1sec intervals.
3. The official max log length is 16hrs @ 1sec/1sec intervals, however this appears to assume that a successful GPS fix is recorded at every attempt.
4. A second experiment is required to determine max battery life where 95% +/- of GPS fixes are successful

5. A second experiment is required to determine the effect on the (circular) log-file (and accumulated metrics) of a longer recording time using 1sec/1sec fixes. By that I mean if, for example in any given session I have travelled 100km in a 16hour period, what will happen to the total accumulated distance once I push beyond that point? Given that the memory/recording system of the Ambit is circular (e.g. starts recording over itself once it fills up) will the “total distance from start” still continue to accumulate, or will each successive data point overwrite another and thereby keep the total distance more or less neutral?

Suunto Ambit External Battery - Experiment 01 - Movescount Extract

Suunto Ambit External Battery – Experiment 01 – Movescount Extract


In case you missed it above, GPX/KML files available here (click the respective file type)



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