With great power comes…

… great  complexity?
If you’re a regular visitor here, you’ll know I have a hub dynamo on my bike, and rely on that to help keep my gadgets charged when out cycling. Especially on multi-day, off-grid rides, with wild camping along the way, your options are either to be self-reliant, or to have all your gadgets run flat and become useless.

I’m increasingly heavily reliant on my phone, and that’s now become my primary navigation device, replacing my aging Garmin. I use the RideWithGPS app, and that’s set to keep the phone screen switched off, to conserve battery power. That means I rely on the voice guidance it gives.

Digital  navigation

When I prepare .TCX files, I’m in a habit of adding points of interest, and additional information (like the name of a river that the road is crossing) as custom cues, which means those are read out to me, too. This is far better (to me) than trying to squint, with my middle-aged eyes that need reading glasses, at the far smaller Garmin screen.

The phone I have is waterproof, rugged (the polite way of saying tough, but ugly) and has a beefy battery. These were qualities I deliberately sought out in a phone, as it was my intention to replace my Garmin with the phone.

The trouble is, phones use a lot more power than a Garmin, Wahoo, or similar, and the GPS function in particular will hammer the battery. In addition, I’m in a habit of taking loads of photos when out cycling, and the phone camera hammers the battery even further. In practical terms, this means that during an average full day’s cycling, I’ll completely drain the phone’s battery, well before the day is out.

Power  bank  +  dynamo

My solution is simple: I use a power bank, which is charged from the dynamo, while I’m riding, and the power bank, in turn, charges my phone. Overnight, in my tent, I’ll also rely on it to recharge my helmet camera and my Garmin, which I take as back-up.

This is an adequate, but not perfect solution. The problems with it are technical, and begin with the difference between 6V AC dynamo power, and 5.2V DC USB power. You see, any conversion of electricity has built-in inefficiencies, and simply by doing a power conversion, you will lose some energy.

Energy  loss

While Li-Ion battery technology is light-years ahead of anything else that preceded it, as a rule of thumb, you can work on roughly 30% energy loss when charging a battery (in real-world scenarios, that will fluctuate, with 30% being the normal worst-case).

Add into the mix that my system effective is two batteries being charged separately, so I’ll lose 30% charging the power bank, then a further 30% charging the phone. Given I have GPS running full time on longer rides, plus taking lots of photos, usually what I find is that during the day, the best I can manage is slow down the rate at which my phone discharges.

As I use the power bank overnight to charge all my gadgets, it will take a beating. What this means is that on rides of quite a number of days, I will deplete the power bank completely, despite the charge from my dynamo. On such rides, I’m forced to rely on my old Garmin Edge 500 for navigation, instead of my phone.

To stretch the timeframe I can rely on my phone for navigation, my plan is to use a far bigger capacity power bank.

Pass-through  charging

Here’s my current problem: not all power banks are equal. Some people rave about Anker power banks (but a surprising number of people have told me what trouble they had with those) but Anker power banks are of no use to me. You see, they don’t support pass-through charging.

Pass-through charging is when the power bank is being charged, while also charging other devices, and that’s an essential aspect to me.

Currently, I’m looking at various options open to me before committing to a particular power bank. While these devices aren’t particularly expensive, they do contain toxic chemicals, and I really want to avoid a situation where I need to get a few. What I’m after is one large-capacity and really good power bank.

Once I’ve selected the power bank to rule them all, I’ll let you know how it goes.