The problem I have is on long trips (via bicycle or on foot) my phone’s battery hits 15% remaining and screen dims mid-trip, which is essentially blank in daylight when navigating. I’m in airplane mode with wifi also disabled. So the only power consumers are the screen and the GPS receiver. Yet I’m still forced to power down, swap batteries, lose the clock time (which GPS strangely fails to correct), and wait to reacquire a GPS signal. Then OSMand remembers the route parameters but forgets the route (a bug). And because the phone’s time is 1am, I have to either update the time or force OSMand into daytime mode.

Big hassle and unwelcome interruption. I see 3 fixes:

1. Repurpose an old phone to receive the GPS signal and feed the lat/long over bluetooth to your navigation phone. Since a bluetooth radio in receive mode consumes around ⅒ the energy of a GPS receiver, the main phone battery will last much longer. The GPS phone need not power a screen, so it can obviously run quite long if it’s only powering GPS chips and bluetooth in tx mode. (refs: GPS uses 13-38%, bluetooth uses ~1.8% / 17.9mA on one chip; math-intensive research I didn’t read because it would make my brain explode)

2. Attach an external USB battery. I reject this because I don’t want to strap another box to my arm and run a cable into my water resistant phone strap.

3. Get an Android-compatible phone with a dual mode LCD, so a low-power e-Ink mode can be used in daylight. I reject this because I boycott Russia and IIRC only Russia has phones with dual mode displays. I would perhaps be open to buying just a raw dual mode screen (not from Russia or Israel) and then use it to replace a cracked screen on a 2nd hand phone.

I guess it’s debatable relevance to solorpunk travel. Two phones in case 1 consumes a little more power overall but it keeps a phone out of the landfill and makes it useful.

update

Found an f-droid app that looks good for this. It will even run on AOS 2 which means quite old phones can be used to feed GPS coords over BT. This app could be useful as well.

Question: I always disagree to “Google’s location service” nag -- (using towers and/or wifi APs) to supplement navigation (no idea what gets shared with Google and also don’t want wifi or GSM eating battery).. but if a separate phone is feeding the fix, then the power problem goes away. But there’s still the sharing problem. Is there a way to harvest the tower info before a trip anonymously and use it without feeding Google?

update 2

I tried using an external bluetooth GPS device -- one that is dedicated to that purpose from the palm pilot days. I was able to pair to it over bluetooth but after pairing it would not connect to it for any kind of session. It’s as if the android does not know what to do with a GPS server.

Some instructions out in the wild say: “In the Android playstore fetch ‘bluetooth GPS’ or ‘bluetooth GNSS’ App.” Well, I don’t do Playstore.

One step is to go into settings → “Developer options” → Debugging → Allow Mock location → enable. That makes no difference for me.

The instructions also say: “Before you launch your GPS software, launch ‘bluetooth GPS/GNSS’, click “connect” and check “Enable Mock GPS Provider” -- which is a non-starter for those not inside Google’s walled garden. Guess I need a free-world variation of this app which apparently uses the external GPS device to feed a mock location. I found these two apps:

• GPSTest - this is an apparently useful test app but seems unable to use external devices
• RtkGps (abandoned¹) - claims to make a connection over bluetooth to an external GPS, but does not work for me. Mentions SiRF IV but not SiRF III, which may be my problem. IIRC, RTK was a SiRF III competitor.

¹ This repository has been archived by the owner on Mar 28, 2023. It is now read-only.