Digital Matter Device FAQ
Through interfacing with our customers about Digital Matter devices, we’ve found some questions are frequently asked about how the devices function. We’ve decided to collect these on our website to better serve your needs.
Frequently Asked Questions
How Battery Life Is Measured
The device will report its battery life with a percentage in each log. This log is via analog 6 in field type 6. The percentage is not directly measuring the battery, rather it is using something called a Coulomb counter to measure the energy leaving the battery. With 2 D Cell LTC (lithium thionyl chloride) batteries, it can be safely assumed that there will be 14 Ah of capacity with the Remora 2 as an example. Depending on what the device reports, the remaining battery percentage can be calculated – if 7 Ah has been used, about 50% of the battery is remaining.
Factors Affecting Battery Life
14Ah is what you can expect out of the battery in the previous scenario assuming normal conditions. However, batteries in all applications are affected by environmental factors. Continuous exposure to extreme temperatures will shorten the life of the battery, meaning your percentage remaining indicates a much shorter timeframe. The device can also increase its battery usage if it has to work harder for a GPS fix, or if it has to report location frequently. To summarize, how often power is drawn from the battery and what current discharge is required will affect the life of the battery. It’s important to note that the device will report 100% capacity if partially depleted batteries are removed and reinserted. Fully charged batteries should be inserted when possible to ensure the most accurate readings.
Predicting Battery Life
With the knowledge of how the device calculates its battery percentage, you can determine how much battery life you can reasonably expect given your usage. If your battery percentage has gone down by 4% in the past 4 weeks, it’s a safe estimate that you use 1% per week, and thus you can expect 100 weeks of life from a battery. Even if the previously mentioned environmental factors are at play, you can see how much the temperature or other factors affect usage and account for that in your battery life prediction. Another important note is that not all batteries are the same. Lower quality or differently-constructed batteries can give different expectations of usage.
GPS Fix Timing Effects on Battery Life
Here is an example chart of how GPS periodic tracking can affect the battery life of a device (assuming normal conditions):
|Average GPS Fix Time
Why does the GPS fix time impact battery life? Digital Matter’s devices use GPS aiding data, which is downloaded by the device to give it positions of the GPS satellites. If this data is recent (within 4 hours), the GPS fix will be acquired much faster, meaning less time searching for GPS and less time using power. This relationship is not linear, because more regular fixes can have less impact with the aiding data. Failed GPS fixes have an effect as well. If a fix fails, the device will immediately attempt another fix for the timeout, which is set to a default of 60 seconds. This can increase battery consumption and is difficult to predict since you don’t always know where you might lose GPS signal, but the battery meter can certainly help.
Digital Matter devices utilize a variety of battery sizes and different chemistries. Important to note is that not all batteries have been tested on all devices – any recommendations given are ones that have been tested on the products. For the Oyster2 and Yabby, BlueArrow recommends Energizer Ultimate Lithium L91 and L92 respectively. Batteries used should be as fresh as possible. Using a tester on the battery before installation is also good as you can tell if the battery will be suitable. Finally, size can play a factor. Make sure to check the fit of the battery in your device when changing brands or types.
Battery Concepts and Chemistries
|All batteries have some level of temperature tolerance. Most commonly a battery will perform the best when it is at or near room temperature, which is about 25 degrees Celsius or 77 Fahrenheit. All batteries will have a specified operating range for safe operation, but repeated extreme exposure to either cold or heat will reduce the life of the battery. In addition to the temperature factor, all batteries experience “self-discharge” when sitting unused. This is a natural and small degradation, but it should still be accounted for.
Depending on the device, Digital Matter devices can support alkaline, Lithium Iron Disulfide (LiFeS2), and Lithium Thionyl Chloride (LTC) batteries. These types have pros and cons, mainly in their capacity, availability, and cost. Alkaline batteries are low-cost and easily available, but also have a very low capacity and are simply incompatible with the power draw of certain devices. LTC batteries are high cost and more difficult to acquire, but have a very high capacity and can support large current draws. The LiFeS2 batteries are in between the other two variants and are almost always going to be a better choice than alkaline because of the low capacity those batteries have.
LTC Battery Types
For the LTC batteries, there are two common variants you will find. Bobbin Type LTC batteries are built for maximum lifetime, but because of this they supply low-pulse current. This makes them unsuitable for almost all Digital Matter devices. Spiral or M-Type LTC batteries are recommended for all Digital Matter devices where required, even if they could theoretically accept a Bobbin type. The Spiral type design batteries do not last quite as long, but they support the higher power draws required by some Digital Matter devices. For example, the Remora 2 can only accept LTC batteries due to its 5V power draw. LiFeS2 batteries would theoretically provide enough voltage, but they are not available in a size that fits the Remora 2. Thus, you want to ensure the Remora 2 will be fully powered with its LTC battery, and that means you need the Spiral type.
Any further questions?
We hope that this article has been helpful for you. Batteries and their usage in Digital Matter devices is a complex topic, but we pride ourselves on our user-friendliness and general customer experience. If you still have questions after reading this page, feel free to reach out to our dedicated and knowledgeable BlueArrow Success Team. They will be ready to ensure you’re getting the most out of your Digital Matter devices and clarify anything you may be confused about.