This transmitter, which is positioned on the jack of your smartphone, will be hampered by a shell or protection around this jack. In my case, I have to dislocate the hull around the jack. As I go mountain biking, the smartphone then goes into the backpack but it's not the most practical.
I said that only the sensor needs a battery. The transmitter is powered by the smartphone (in my case, a Sony Xperia Z1 Android).
For heart rate measurement as described by others, we must place the sensor under the pectoral, but not lower.
It is advisable to moisten the electrodes on the front sensor. Although sweat will do after This allows a measure from the beginning of the sport.
Under these conditions, it is very accurate.
To sum up:
Strengths:
- Cheap,
- Accurate,
- Good complement Runtastic.
Low points:
- Exceeded: for the same price now we have the Bluetooth model (here)
- The transmitter is not practical.
I use it for over a year and I am satisfied. The sensor battery holds up well (not replaced last year as I use it often - about 1 to 2 times per week).
However, the new model is certainly preferable to a new purchase.
Note (see comments related to this opinion): the Bluetooth system of the new model is only compatible with Android 4.3 and higher smartphones. So, the model evaluated here could interest you if you have not Android 4.3.
Small precision: the application Runtastic Pro no longer exists. It became a Pro subscription not related to the application, but linked to the account of the user. Further proof that this product is exceeded.
