With only two days left until departure for Glastonbury, the Artificial Pancreas portables decision has been made, and it’s not quite what I originally thought I’d do in this post.
At that time I was stuck between the following choices:
- Take the iPhone linked rig, run it with Dexcom on the iPhone (and the local Loop based feed if I can get it to build) and use that for the duration, with a PAYG SIM to guarantee connectivity; or
- Get hold of some enlites, build a Medtronic system just for the Festival and put up with slightly less accurate BG numbers, a couple of additional calibrations a day, but know that it will all work in spite of network connectivity, with the additional ability to fall back to the 640G with glucose data should everything go belly up.
- Then, or course, there’s the other option. Don’t take OpenAPS, use Loop. Whilst this is the easiest of the three, I’d prefer the oref1 capabilities to the current Loop ones. But it’s always worth considering and taking RileyLink with me.
- Buy an enormous great battery case for the Pixel, and run from the Android phone as I do now, with all the smarts I’ve shoved into it, and simply leave it in my bag. Disable the oref0-online cyclic functionality and simply have bluetooth connect the PAN at reboot (this technically may work for the iPhone too).
Following some further research into mobile phone signals, looking at power options, and everything that goes with that, I’ve come to a conclusion on what this will look like, and to my surprise, it isn’t what I expected.
First up, the key decision points (in order of importance for me) were:
- Ease of Use/Portability
I put power and connectivity into the same bracket as they are two sides of the same coin. Together, they influenced my thinking. How?
- If there is no connectivity I need a solution that runs without it.
- If there are two many components needing power that can’t last 18 hours between charges, I have an issue with running anything.
Power rapidly becomes the most important as without it, there is no OpenAPS. And connectivity, relatively, is simple. My normal carrier has 3G coverage over the site:
There’s also the big splash EE made about having a permanent mast and plenty of bandwidth, so a tactical SIM swap is also a very big possibility, as the only thing that fails when I swap phone number is WhatsApp, which, let’s face it, I don’t use a lot. And I can always stick my SIM in a different phone set in a power saving mode.
So connectivity? Accounted for!
On to power next then. This is where I started to get a little more concerned. The facts are:
- My normal android phone (Google Pixel) for the rig for offline use lasts around 18 hours and finding a battery case for it has proved rather more difficult than I imagined. There are some around, but the one I ordered a month previously hasn’t turned up (Zero Lemon, I’m looking at you here)
- The rig itself lasts around 30 hours on the 4400 mAh battery
- My iPhone 7+ lasts around 28 hours and I have an 8000mAh battery case for it
Based on this data, it became clear that the normal Android solution doesn’t really work as I’m on the edge too frequently in roaming a field and potentially running out of power, and I’d rather not lug multiple battery packs (it’s bad enough when the pump does that). So this leads to the iPhone as the “best” option for the connectivity and control.
But there’s also the rig issue. My estimated usage over the 5 days is around 20,000 mAh. Do I keep a large power pack back at basecamp to recharge the rig battery (an inefficient mechanism at the best of times)? Even with those larger battery (4400mAh and 6600mAh) packs, it’s unlikely that I’m going to get them fully charged overnight, and I’ve had some bad experiences charging LiPos through the explorer board from power packs in the past.
As I’ve mentioned before, I”ll be carrying a back pack, and that changes the solution rather. So I’ve come to the conclusion that simply rigging up a 25k mAh battery pack to the explorer board and having that sit in the backpack is likely to be the most sensible approach for this five day period. No charging, no mucking about. Just a week of power on a battery. Job done.
So we’re there with the power and connectivity. Keep charging to a minimum and just get everything going. But what about command and control?
With the best will in the world, while there’ll be signal, it may not be all that fast, so this is where the local options come into play. With both the xDripAPS feed from the LookOut version of Loop working and my local status pages on the rig, as long as there is a data signal to allow the iPhone to share a Bluetooth IP address, I don’t need to access NightScout to see what’s going on. That’s enormously helpful.
Add to that the changes to the Dexcom app that makes using the Apple Watch possible, and the complications/dockable apps that can now be run on it, and the command and control has become even easier (yes, I know it needs recharging nightly, but that’s eminently manageable).
So there we have it. My “Glastonbury” rig. Lots of power, an iPhone, an Apple Watch and the rig.
And of course, back-ups for everything in the car, just in case!