What about the battery?

The ReLog uses a Li-ion battery, which means that the unit is rechargeable and will be possible to use in the field for many years as long as it is handled properly. The maximum battery life when running at full speed (maximum sampling frequency) is around 72 hours. This can, however, be extended dramatically by using trigger functionality.

Battery specification

The ReLog uses three different sizes of batteries to accomodate for your needs. This provides you as a user the opportunity of measuring for a substantially longer period compared to what other solutions offer.

ChemistryRechargable Lithium Ion
Nominal capacity2,600 mAh - 3,400 mAh
Minimum capacity2,500 - 3,300 mAh
Operating temperature-20°C – 60°C (-4°F to 140°F)
Storage temperature1 month : -20°C – 60°C (-4°F to 140°F)
3 months: -20°C – 45°C (-4°F to 49°F)
1 year: -20°C – 20°C (-4°F to 4°F)
Battery time at full sampling rateReLog S: 80 h
ReLog M: 95 h
ReLog L: 110 h
Battery time when using trigger/alarm modeUp to several months of recording (depending on trigger setting, please reach out to us for further specifications)

Battery life

The reason that we provide estimates of battery life is that a Li-ion battery and its performance are affected by several variables at once. The main reasons are that impacts the battery life are:

  • Amount of charge cycles
  • The operating temperature
  • Charging temperature
  • Storage temperature

If you’ve ever lived in, or spent time in, a cold country (we’re based in Sweden so talking from experience here…) you know that an electric car never reaches its target kilometer range. We’ve even tried to turn the AC off while driving in – 5 degrees Celcius to make sure we would reach our destination but it didn’t help much. The moral of that short anecdote? If you will be using the ReLog in cold, or very hot temperatures, pleases be aware that battery life could be significantly shortened and calculate your measurement activities accordingly.

We will soon be updating this page with a battery life estimation calculator so you can estimate the performance yourself. If you would like us to help you with the estimation, feel free to reach out to us! 

Can the battery be replaced?

No, unfortunately not. Our chosen battery has an estimated cycle life of 500 cycles. One cycle is defined as one charge and one discharge. When approaching 500 cycles and when exceeding it, the capacity of the battery will be decreased.

Due to the different variables (temperature, charing, storage, etc) that the battery will be exposed to, the battery life is estimated to 2-3 years.

Battery life calculations

For your convenience, we have calculated a few different scenarios for how long the battery will last before it needs to be recharged:

ReLog S

Sample rate (Hz)Est. battery life (h)
25,000 Hz80 h
10,000 Hz95 h
5,000 Hz125 h
1,000 Hz150 h
100 Hz250 h

ReLog M

Sample rate (Hz)Est. battery life (h)
25,000 Hz95 h
10,000 Hz115 h
5,000 Hz150 h
1,000 Hz195 h
100 Hz300 h

ReLog L

Sample rate (Hz)Est. battery life (h)
25,000 Hz110 h
10,000 Hz130 h
5,000 Hz175 h
1,000 Hz210 h
100 Hz330 h

What if I need more power? Can I use an external power source?

Yes, you can! At least if you’ve chosen the ReLog M or the ReLog L. Both the ReLog M and the ReLog L includes “logging-while-charging” features which allows you to use an external power source to prolong the lifetime of the ReLog. Let’s paint a picture and look at an extreme example: 

You’ve recently bought your ReLog and wish to record at 100 Hz. The built in battery provides 330 h (13,75 days) of battery life but the 128 gb internal memory enables you to record measurements for 2460 days if you’re using 100 Hz as sample rate. The ReLog L consumes about 10 mA while measuring at 100 Hz so if you would connect an external power source that has 590,000 mAh or more you would be able to power the ReLog for the entire duration of the measurement.