Tuesday, May 30, 2023

Battery Life of Phones Running Location Services

Phones and tablets are often valuable backup navigation systems, with many excellent navigation and weather programs available such as qtVlm and LuckGrib. It is known that location services, which we must turn on to access the internal GPS, cause an enhanced drain on the battery. Here we look into how much of a drain is this.

The topic came up again as we introduced the new low-cost miniature AIS called dAISy that will not only run in any computer-based nav program, but it will also work plugged into an Android phone or tablet running qtVlm. The battery-life question then extended to how much more of a drain will it be to run this AIS in a phone, which will be on top of the drain from the required location services.  

Below we see the battery drain with with dAISy being fully powered by an Android phone along with qtVlm.

Figure 1. A new Galaxy A03s Android phone running both qtVlm and the dAISy plugged in and monitoring AIS Traffic without external power.

This test ended as shown when we noted that the dAISy had quit working at about 5.5 hr, although qtVlm continued to function.  We suspect that the phone shut off the USB connection at some level to protect battery life — not realizing that in this case the dAISy had in fact almost negligible effect on the drain as we see below.

Note too that this direct plugin arrangement of the dAISy is just for quick observations of traffic, up to, as we know now, four or five hours.  For continuous operation, the dAISy should be connected with an OTG adapter which allows for external power application.

To see how this differs with no dAISy, we have the data below for full navigation functions running in qtVlm but no USB attachments. 

Figure 2.  A new Galaxy A03s Android phone running qtVlm with a continuous GPS fix.

We notice here that the rate of battery life drain is essentially the same as with the dAISy attached. In short, this phone running location services and a large nav app loses battery life at about 10% per hour, with or without the dAISy attached.

This is a new phone with its new battery; older phones might not be as efficient.  Also note that this Galaxy A03s is an economical choice for a backup nav system at about $88 for refurbished unit with both GPS and a barometer... plus it will run an inexpensive AIS system.

Below is the same measurement as Figure 2 using 18-month-old iPhone 11.

Figure 3.  An 18-mo-old iPhone 11 phone running qtVlm with a continuous GPS fix.

So we see a rough generality emerging, namely the battery drain from location services in action is about 10% per hour.  This will of course have to be tested to learn what other factors may influence this observation, but at least we have a starting point.

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