Dynamo hubs and USB-C

Implications for headlight choice

For decades there has been a desire to charge batteries and devices from bicycle dynamo hubs. Being independent and self-sufficient was good. Interest ramped up with increased use of and reliance on smartphones. Now the problem of needing to charge them has been turned on its head by the arrival of fast-charging standards, USB-C and better power banks.

If it was not for our need for lights, we would not have the dynamo to begin with. Early bicycles used dangerous gasses to make light. Incandescent bulbs came along at the start of the 1900’s but bulbs vibrated and broke. It was accepted that a bicycle needed to have a light that worked. The photo below is of a 1919 Mead Ranger bicycle with a tungsten-filament lamp and a #6 size dry cell slung under the top tube. (sheldonbrown).

When bicycle hub generators arrived in the 1930s, there was a need to regulate their power output. Without uniform standards in power output, bulbs would blow out at speed. Government regulations became, effectively, global regulations. Today, internationally traded bike dynamo hub, for a given wheel diameter, are restricted to 6 volts and 3 watts.

These regulations have meant that the electrical output of hubs has remained the same. But, in the smartphone world changes have been dramatic. For travellers, connectivity keeps improving along with availability of sims. Smartphone cameras have got better to the point where we don’t need to take separate cameras. Navigation is also so good we don’t need a Garmin etc. They add up to us being more reliant on the phone and more dependent on being able to keep it charged. Enter fast charging.

If you bought a new phone since around 2020 it is likely to support “fast charging”. You may have needed to buy a fast-charger wall-plug separately. Whereas the previous charge rate was 5 watts, a Samsung Galaxy S21 released in 2021 charges at 25 watts. The iPhone 12 released in late 2020 is also fast-charging (if you have the matching cable and wall plug).

This is quite recent though. Since they smartphones arrived, charging had not improved much until about 2020. This was a problem for bike travellers. By 2010, work on ways to grab some charge from a bicycle hub and deliver it eventually to a device like a smartphone appeared. There were issues from power fluctuation from speed variation. Intermediary batteries, or super-capacitors were needed. There are now over 20 hub dynamo USB chargers that have come to the market.

Testing gets done so we can see some objective data about these products. This includes measuring the wattage output at 20kph. At that speed, output levels of 3 of 3.2 watts is common (Sinewave Reactor, kLite USB Charger, Sinewave Revolution, Busch & Muller E-Werk). Some put out a little more, such as the Cinq Plug 5 Plus (4.6 watts).

No one making equipment for phone-charging from bike dynamo hubs claims they are more than trickle chargers. Their goal was, at best, maintaining the battery charge, or slowing its decline. Speed needed to be maintained, thereby limiting usefulness on off-road rides.

When you are riding with someone you both keep your lights on to always know where you each other is. Having the lights turned off all day to preferentially charge a phone seemed like a needless sacrifice when

  • you could mostly charge the phone on grid power at night, or
  • you had enough in a power bank, or
  • you had solar recharging.

We all use mains power

In this climate-action era, the world is becoming more and more electrified. If we get an e-bike, e-cargo bike or electric car, we’ll connect it to the grid. We may have solar on the roof, also connected to the grid. Grid power was equated to fossil fuel burning but increasingly, it is from hydro, wind or sun.

In an urban setting, our lights are more important than is charging our phones on the bike. But for the bike travelling community there seemed to be a remaining case for independence. That’s probably what the brochures say. We might be ‘away’ from the grid. We may be in the bush, so to speak. But for how long? Travellers go into towns for several reasons, not least of all, for a hot shower!

On the Munda Biddi ride in WA, perhaps the longest off-road trail anywhere, the longest section between small towns is three days. There are huts but no power in them.

In most of that country there is no phone or internet reception. There’s not much navigation that you need to do. You do need to have the GPX track on a device but you only need to occasionally check it. So, there’s not much use for the phone, apart from taking a few photos like this one.

When staying in towns, even if camping in the caravan park, power is available. If charging takes an hour or two, we are going to be able to do it in any town. If it takes 8-12 hours, we can’t do it in a café and we have to minimise use of the smartphone. Even if we have a charging device hooked to the hub dynamo, with the trickle of current we can get, we have to minimise use.

The step forward was not going to come from yet a better way of charging from a hub with a 3-watt output limit. There have not been any breakthroughs that have significantly improved that technology.

Fast charging standards change things

USB-C is a connector type, but behind it there can now be one of the fast-charging standards. (There are some USB-C connections that are not using the special chips). In this picture the standard USB-C connector is on the left. iPhone, needing to be different, has a connector on the right called Lightning, although there are rumours that iPhones will move to USB-C soon to align with the latest MacBooks.

A USB-C connector next to a Lightning connector

Qualcomm’s Quick Charge chips have quickly become widespread. Samsung smartphones and tablets, since 2021, have used them. Quick Charge 3.0 dynamically boosts voltage from 3.2V to 20V. Peak power is 18W. That means, theoretically, phones with a 3,500mAh to 4,500mAh capacity can gain about 80 percent charge in just 35 minutes when the battery is depleted.

The other main fast charging standard is USB Power Delivery (PD). This is a newer protocol in which two compatible devices negotiate on the fastest charging option available. It also allows for power to flow both ways. Quick Charge, on the other hand, works by increasing voltage rather than amperage.

The implications for bicycle travellers are that we can recharge devices so fast that we don’t mind being dependent on short periods of access to grid power. This does require that we have a more recent device (iPhone 8 and above for example), plus the correct cable and the correct charger. All three components need to support fast charging for it to work. On some phones you must activate it in the settings. The fast-charging wall plug might be an extra purchase. But it is there.

Fast charging arrives for power banks (portable chargers)

Fast-charging has arrived to address the problem that power banks had: they also took too long to charge. If you are researching for a purchase you need go no further than pcmag or Amazon and look at specifications, price and popularity.

Power banks that fit in your pocket are typically good for a full phone charge or two.

You need a wall plug, cable and power bank that are inter-compatible to ensure fast charging works. An example is the pictured Anker Power Bank, USB-C Portable Charger 10000mAh with 20W Power Delivery, PowerCore Slim 10000 PD. With the wall charger and cable, this set-up is under 300gms or one cup of water equivalent.

Most phones can be charged twice from a 10,000mAh power bank. Charging the power bank now takes about 4½ hours. It used to be half a day or quite a bit more.

If you expect to run your phone down to zero charge in one day, which would involve a lot of usage, having this 10,000mAh power bank means you want access to grid power after three full days off-grid. An option would be solar charging which is a related subject not covered here. Most would agree, travelling by bike, that they are not away from grid power access for longer than three days at a time. And we don’t drain the phone so fast in remote off-grid places.

Techniques for preserving charge on your smartphone

Fast charging allows us to be more liberal with smartphone usage but there are simple ways of stretching out the charge that are still worth noting. If you are riding in areas with no mobile reception you can flick to flightmode and save a lot of power as your phone stops looking for a signal. Or you may want to receive phone calls/sms but don’t mind having wifi and bluetooth turned off. The phone is not searching for internet connections.

With everything blocked ( flightmode, wifi, bluetooth), GPS chips still show your exact location on an embedded map. If you have downloaded, for example, the OSM (open street map) for the state, region or country, you can have it in front of you, showing your exact location, on a route you have uploaded or developed and saved.  If your phone is on a holder, you can zoom in and out whilst riding, and be using very little power.

This all involves the good accessibility of the device. We used to carry our phones in our back pockets and not use them much. With better power recharging we can use them more, even if just for their excellent cameras. Very rigid phone mounts have made this workable. The one I use is made by Rokform. The arm pivots off a topcap.

It is so rigid that you can type on the screen whilst riding. Examples of things you can do (whilst still riding) include making phone calls, using the speaker, and chatting as you ride. In places where it is safe, you might turn the camera app on, remove the phone from the mount and take a picture without stopping. You can zoom in on the contours on your OSM map to see how much more there is to climb. You can play a podcast using the phone speaker. When in internet range, listen to the radio on the ABC listen app, check mail.

Focus on Headlights

The dividends to bike travellers from the arrival of fast charging are not just less need to charge from the hub dynamo or that we can exploit the smartphone more. We can return the focus to dynamo headlights. It’s logical to use the 3 watts power from hub, solely to run better lights. Better is not simply brighter though.

LED chips can produce bright white light without helping visibility much. There are different chips that produce light in different parts of the spectrum. Therefore, on bike paths, you sometimes see blindingly bright lights coming towards you. But visibility is not brought about simply by brightness. In most countries there is no regulation about this. Manufacturers compete on price and brightness, not on the level and distance of visibility. Germany though, fortunately, has imposed strict regulations for bikelights, under a standard named StVSO.

In the lighting world, lumens describes the total amount of light emitted by a source, telling us, in simple terms, how bright a given light will be. Under the German standard, with StVZO-compliant lights, it’s all about a different unit of measurement, the lux. If lumens can be used to measure the amount of visible light thrown out in all directions, lux is the measurement of light at one point on a surface. Lux is about being able to see better whilst lumen is …a number.

Aside from the better light visibility provided on the latest top-end bike headlights powered from dynamo hubs, there are other features. Coming on and not flickering above quite low speeds is a requirement in StVZO. ‘Standlight’, where the light stays on for some minutes after you stop, such as at traffic lights, is common. Also, there are sensors that run the light at a lower level in daytime so you can always leave it turned on.

 It was only in 2021 that available brightness in hub-dynamo powered lights reached 100 lux. The German maker, Busch & Muller achieved this with their IQ-X model, pictured here. The path is well lit at 45 metres ahead. Notice how the rounded top of the frontal area is not lit. This is a key aspect of the German lighting standard designed to not blind on comers.

A few European makers work in this space, B&M and SON being dominant. Asian makers such as Cateye, are not currently showing interest in dynamo powered StVZO-compliant lights.

Today (2022) on a travel bike, it makes sense to have a hub dynamo, an excellent headlight such as the B&M IQ-X, a phone that supports fast charging, a rigid phone mount such as a Rokform, and, for longer trips, at least a 10,000 mAh powerbank that also supports fast charging.

Interest in charging devices designed to grab a bit of current from the hub are likely to fade away. As recently as 2019 that would have been unthinkable.