How to charge electronics when bikepacking

If you don’t want to rely solely on paper maps and a “dumb phone” that lasts 14 days, you’ll need to handle charging your devices on longer trips. And there can be quite a few:

• Phone
• Head unit
• Lights
• Electronic shifting
• Satellite tracker
• Smartwatch
• Potentially others

Basically, you have two ways to charge these devices—using a power bank or a hub dynamo.

🔦 Dynamo

By dynamo I don’t mean the old bottle dynamo you may have had on a Favorit. There are modern dynamos, usually in the front hub, that have minimal drag and can power your light directly or charge your electronics. The hub is heavier, fairly expensive, and you’ll need to have your wheel rebuilt to use it. And even though it’s very efficient, you’ll lose a few watts when using it. You can’t cheat the laws of physics.

When powering a light, the nice thing is you don’t have to manage output. The faster you ride, the brighter it shines. Some lights have a capacitor, so you still have some light after stopping. It’s more suitable for gravel and road bikes, where you typically ride at higher speeds. On MTB you’ll hit the problem that in tough terrain you ride slowly but need a lot of light. You won’t avoid a battery headlamp anyway.

To charge from a dynamo you also need to buy a special converter that turns AC into DC. Charging isn’t very fast and works best on flat to gently rolling routes. Depending on the device, charging only kicks in from about 10 km/h. Some phones can’t be charged directly and you need to use a power bank, which adds more losses.

A dynamo is a good fit if you don’t want to stop in civilization often—it’s more romantic—and you choose a faster route.

🔋 Power banks

Power banks are better in terms of weight and price. Even if you buy an expensive ultralight carbon power bank. For choosing the right one, I recommend the guide How to choose a power bank for bikepacking.

The main downside, of course, is that sooner or later you’ll have to stop somewhere and charge. One option is to occasionally book accommodation and charge everything overnight. In that case, larger power banks are more useful and you don’t need blazing charge speeds.

Another option is to stop at a restaurant and top up there. In that scenario you want the fastest charger possible, so you don’t have to linger too long. I use the AlzaPower G500CC 45W weighing 78 g, which charges at 45 W if you use one port, and 30 W/18 W if you use both.

If you need to charge devices quickly, you have to pick the right strategy. Charge end devices with higher charge rates first. I, for instance, use a Google Pixel 9a with a max charge rate of 23 W, which fills up in just over an hour. Why start with the phone? If I first charged the power bank and then charged the phone from it, I could lose around 30% of capacity to conversion losses.

As my second device I usually charge the power bank. Mine charges at 18 W and fills in roughly an hour and a half. Always keep in mind the limits given by maximum charge rates. My charger outputs 30 W and 18 W and my two main devices top out at 23 W and 18 W, so the charger isn’t the bottleneck.

Why do I charge the power bank second and not another end device? For example, the Garmin Edge 840 only charges at 5 W, which is too slow and not worth it even when factoring in losses.

Then it’s up to you to figure out how long and how often you’re willing to sit in a restaurant to charge everything. There are other options too—sometimes there are outlets at train stations—but you still have to stop.

When charging devices from a power bank, I recommend using a USB‑A cable. That way the device will charge more slowly and the energy transfer will be more efficient.