In this post we have compiled and reviewed a number of dynamo hub charging units for USB devices. We also have a comprehensive resource which overviews dynamo hubs, solar panels and external batteries, check out the Ultimate Power Resource For Bicycle Touring.
People with some electrical know-how have also been making their own battery kits, and I believe there are a few 'how-tos' floating around the internet if you wanted to give it a try…
What can you charge from a dynamo hub?
We charge our Apple iPhone 5S smartphone, Sony TX10 digital camera, Airstash Pocket Server, Garmin Edge 800 GPS and 6700mA external battery.
You can also use the dynamo to charge batteries (AA, AAA etc), Kindles, GoPros, USB powered lights, headtorches, speakers, MP3 players and much more.
Which power supply do we use?
We've used the Pedal Power products for a few years now, and have recently made the switch to Tout Terrain's The Plug III, which we believe is the best power supply going around. It's simple and elegant, theft-proof and achieves full USB power (5V/500mA) at 12km/h.
The Plug III is a USB port at the headset cap which draws power from a dynamo hub or sidewall dynamo. Sneaky electronic parts hide away in your steerer tube providing your bike with a very clean look, with a minimal weight penalty (perhaps 150g). The Plug cleverly converts AC into DC power from your 6V dynamo for charging USB goodies.
Pros: By far the neatest solution to dynamo charging. It charges our smartphone at 12km/h. It's theft proof – you can leave it on the bike when you lock it in the street. It's aesthetically pleasing and well made. It's easy to install. The Plug has been refined over a five year period. Every release has been better and better and reliability issues have been addressed. We feel that The Plug is now near perfect.
Cons: There's no cache battery, so if you dip above and below 12km/h the charge will go on/off (we charge into a battery when this is the case). You cannot charge devices post-ride. The USB interface gets a bit rusty, although this hasn't affected our units performance. You can't mount computers/smartphones on your stem as easily. It's pretty pricey compared to other products.
Price: $215 USD
This dynamo cable features a built-in 2200mAh battery which allows you to charge as you go, or charge post ride. It worked flawlessly for the two years we put into it. The only issue we had was working out how to mount it to our bike – we eventually cable tied it on, but was always worried someone would touch it when we locked it up in the street.
Pros: Cable and battery in one with battery storage. Cache battery allows you to not loose charge when you've stopped momentarily. Works flawlessly.
Cons: Mounting onto the bike doesn't come easy – we feel you need a front pannier to run it well, but it's not a necessity. Battery charge is slow from power point (same speed as charging from hub). Vulnerable to theft if left on the street with your bike. Didn't charge our smartphone (we could only charge via the V4i battery back – apparently there is a new cable attachment for iPhone 5).
Battery: 2200mAh Lithium Polymer
Price: $180 USD
This cable/battery combo allows you to charge straight from the cable or through the battery. We've been using this kit for a few years now and we've been able to charge any device that we plug into the battery. The battery takes roughly 10 hours of ride time to fill, and will charge an iPhone four times, or our Garmin 800 GPS twice.
Pros: Heaps of battery power to keep your gear running the most out of all of these options. Plug in any device. You can charge the big battery up from the wall. We can even charge our iPads from this battery!
Cons: You really need a handlebar bag or front pannier to run this well (we charged the battery in the top of our front pannier). Battery charge is slow from power point (same speed as charging from the dynamo). Vulnerable to theft if left on the street with your bike.
Battery: 6700mAh Lithium Polymer
Price: $290 USD for the V4i Battery Kit and a Super-i-Cable.
The eWerk is one of the most widely used power supplies amongst bicycle tourers. The kit connects to your hub and from there, you can then plug USB devices into it. A small stylus that is housed at the bottom of eWerk is used for adjusting two turning knobs controlling voltage (2.8 to 13.3 V) and current (0.1 to 1,5 A) quickly and variably for all the usual applications. The eWerk provides power of up to 16 W, and all that with minimal idle losses at 30 km/h. At a speed of about 15 km/h, the eWerk charges as fast as a standard mains connected charger.
Some devices, such as the iPhone, require a constant voltage from the charger, so for devices like this, a cache battery must be charged into and then the phone can extract power from that. This battery is purchased separately.
Pros: Adjustable voltage and current which allows for efficient charging of devices which have different charging requirements. Great mounting kit for the top tube.
Cons: Quite expensive. Need the cache battery to charge smartphones (extra $105). Vulnerable to theft if left on the street with your bike.
Battery: 1400mAh Lithium Polymer
Price: $210 USD + Cache Battery $105 USD
The USB Werk is the more recent release by Busch and Muller. It is a stripped back version of the eWerk and with a cache battery built in. The price is now very competitive with other options. If you only need to charge basic USB devices (GPS, smartphone etc), this will do all that you need!
Pros: Cache battery built into this power supply (unlike the eWerk) so that you will not loose charge if you've stopped momentarily. Neat mounting kit. Much more affordable than the eWerk.
Cons: Vulnerable to theft if left on the street with your bike.
Battery: Unsure of the size, but presumedly it's less than 1400mAh.
Price: $150 USD
This is one of the original USB charging products. The Reecharge kit wraps around the headtube neatly with a cable running down to the dynamo hub. It offers exceptional value for money!
Pros: Charges most devices. Can be charged from the wall. Neat mounting setup. Cache battery allows you to not loose charge when you've stopped momentarily. Really good value.
Cons: Vulnerable to theft if left on the street with your bike.
Battery: 1600mAh Lithium Polymer
Price: $99 USD
This small and 100% waterproof charger can be hooked up directly to phones or power packs, and is especially popular with bike tourers given it's affordable pricetag. The unit is actually matchbox sized, and had really proven itself in the field. The Revolution starts producing power at 5.5km/h and achieves full power at 14.4km/h.
Pros: Completely waterproof (see the pic HERE) and charges most USB devices. Manufactured in the USA. Really good value for money!
Cons: You cannot charge devices post-ride (no battery), although you can ride and fill up a USB rechargeable external battery instead. Zip ties make the bike mounting semi-permanent and not particularly neat. Vulnerable to theft if left on the street with your bike.
Battery: Nil, but according to the manufacturer, a built-in battery version is in development.
Price: $120 USD
This is the latest dynamo power supply by Sinewave, and is the only direct competitor to The Plug III. Currently, it's too new to the market to get an idea for how reliable it is or how well it performs.
Pros: Super neat with a smaller stack height than The Plug III. It's theft proof – you can leave it on the bike when you lock it in the street. It's aesthetically pleasing. Manufactured in the USA.
Cons: There's no built in cache battery. It's harder to mount computers/smartphones on your stem. It's pretty pricey compared to other products, however it does have a price advantage on The Plug.
Price: $180 USD
The LightCharge is the cheapest option here, although it often gets mixed reviews in terms of reliability. We recommend having a look into this product before making a purchase.
Pros: The price is right. Charges many devices. Super simple and lightweight.
Cons: You cannot charge devices post-ride (no battery). Vulnerable to theft if left on the street with your bike.
Price: $70 USD
Introduced to consumers at the 2012 Eurobike tradeshow, this bright dynamo light incorporates a handlebar switch and USB plug to charge and ride. It is a fantastic, integrated design, however unfortunately has mixed reviews on it's reliability.
Pros: A super bright dynamo light with a really broad beam. It features a neat cable and remote switch. Charges most devices. Cache battery allows you to not loose charge when you've stopped momentarily. Relatively theft proof given it's bolt on mounting.
Cons: You cannot charge devices post-ride (no battery).
Price: $260 USD
The Revo is probably the brightest dynamo light on the market. It has a port which allows you to hook up Exposure's 'boost' cable and charge USB devices with it. We've heard mixed reviews about the capability of the USB charging, which leads us to believe that you shouldn't buy it for USB charging alone…
Pros: Super bright and well made dynamo light.
Cons: From most reports, it's not the most efficient USB charger. It only fits on a handlebar mount. Vulnerable to theft if left on the street with your bike. You cannot charge devices post-ride (no battery).
Price: $300 USD
I don't know too much about this product, however it sounds like it's designed for smartphone charging. The handlebar clip is a great idea for those not using a handlebar bag or front pannier. Nice and simple – great price. Any more info – give us a shout!
Battery: 2000mAh or 2700mAh (+$15) Lithium Polymer
Price: $125 USD
For more information on dynamo hubs, solar panels, power supplies and external batteries, check out our Ultimate Power Resource For Bicycle Touring.