Bicycle iPhone and USB Charging – Conclusion

With the TuneCharger board burned out, and no feedback from the company that produces (produced?) it, I needed to find some other method of getting power from the dynamo into batteries. … That is, if I still wanted to do so.

Almost two years had gone by since I originally began this project, so I figured an online search would reveal a new device that elegantly solved the dynamo-USB-battery-iPhone problem. No such luck. The closest I could find was the “Ree-Charge Power Pack”, and it had some obvious flaws:

  1. Not much battery capacity
  2. Did not integrate very well with a dynamo-driven headlight
  3. Only one USB port

A similar device, but with similar flaws, is the NC17 iPhone Hub Charger.

On the other hand, it didn’t really matter to me as much as it had before. For over a year, I’d been riding with a combination of parts that worked in all the situations I got into.

The Headlight Factor

Headlights take up a huge amount of power. There’s just no getting around it. When you power those headlights with a battery pack, the battery pack is often very large and heavy, and even if you could charge USB gadgets with it, you wouldn’t want to, because you’d be placing yourself at risk. If your headlight dies because you used all that power to charge your phone, you’ll feel like quite the chump, sitting in the dark by the side of the road playing Enviro-Bear while you wait for a ride home!

If you connect your headlights to a dynamo, you are generating – and using – the energy to drive those lights as you go along. There is no need for you to accumulate it in a battery, so any battery pack you bring can be used entirely for your gadgets. You can drain that battery all the way down to nothing, and still be confident that when it gets dark, your lights will guide you and reveal you to drivers.

At first, I thought of a dynamo as an instrument primarily for charging gadgets, and the fact that it powered headlights was a convenient bonus. But it turns out that the best feature of a dynamo is its ability to take headlights completely out of the power equation. Sure, you could also use one to charge a phone, but how often do you really need to? Especially if you’re carrying a little extra capacity anyway, for use on and off the bike?

Even though my TuneCharger was dead, I could still use the USB board and the batteries, as long as I charged them with a wall-charger at home. … And that’s what I did, for almost an entire year, including rides through the Fremont hills, rides around San Francisco, and five or six rides in San Jose Bike Party.

Later Developments

For my trip from Colorado to Ohio, I was certain I wanted to bring a laptop. With that in mind I figured I could save on the weight of a charging brick by getting a battery that could charge on a USB port, or from the little doodad that the iPhone uses. Eventually I settled on a battery called the “Trent iDual-Port Pack IMP50D 5000mAh External Battery Pack and Charger

Over many days of riding, I have never needed any more capacity than the 5000mAh battery pack in a single day. On my ride from Colorado to Ohio I put in one 18-hour day of riding, and used it to charge the iPhone twice and an iPod once.

There was a time when I went camping with an iPhone and an iPad, and for that I brought along a monstrous 10,000 mAh 14.8-volt battery pack made from four of the cells like the two I purchased for this project. I watched movies and typed journal entries well into the night for a week without wearing it down. Even if I had the ability to charge that thing with the bicycle, I wouldn’t have been able to, since I was not on the bicycle for most of the week. A solar panel would have theoretically done the job, if I’d been willing to wait a while… But it still would have been a moot point because the ranger station was only a five minute ride from my tent, and they had wall sockets I could use, rain or shine.

Of course I could have also brought along the Solar Juicz 55 Watt Folding Solar Panel and charged a laptop and a bunch of other stuff while I hung around the campsite. Many options these days!

All in all, I’d say it’s “mission accomplished” for this project. I’m quite pleased with the setup I have now, and I hope the information I gathered along the way is of some use to all you other Do-It-Yourselfers out there!

14 Responses to Bicycle iPhone and USB Charging – Conclusion

  1. Edmund says:

    Thank you for sharing your trials and tribulations; fantasticaly useful and at the end refreshingly honest. You have helped me come to the same conclusions by only reading your article. 10/10

    • TheCuriousCyclist says:

      You’re quite welcome. I’m curious … what conclusion did you reach, and what gadgets did you get, to address that conclusion? There’s definitely more than one style of bicycling, and more than one way to solve the problems at hand…

      • Edmund says:

        I tour Europe every summer. I decided that given the weight, cost and complexity; a dynamo system to run the head light or charge USB devices wasn’t the best solution. I purchased an off the shelf 10 000mAhr Li battery with integrated USB output and separate charger; then mounted the battery under my rack. Upgraded the LED and driver circuit in my headlamp so it runs twice as brightly for half the current. The head lamp will now last the two week trip as I don’t ride into the night very often on long trips. The battery will last a minimum of 3 days charging phone and running GPS continually or a week if I don’t have the GPS on continually. I don’t camp every day so will be able to charge the battery at least every 4 – 5 days. My battery charger can run on 90v to 240v AC and weighs no more than a few ounces, it has a changeable face plate to cater for different pin types. I’m currently considering making a simple adapter so it can charge AA cells as well. The current capacity and efficiency of batteries and LED devices is staggering, being totally power self-sufficient sounds fantastic but at the end of the day, what do you really need?

  2. Max says:

    Great, I’m cycling (on a recumbent too !!) from London (UK) to China (Beijing) and I wanted to build a similar system !! But just to recharge batteries and power lights so I’m going to by-pass the battery pack. I will recharge only when I ride. One question, if you try to recharge an iPhone or a battery (for a camera 3.7 V , 1100 mA), do they stop charging themselves when they are full or do you have to know when to stop charging them in order not to overcharge them ??


    • TheCuriousCyclist says:

      Hello Max!

      Without getting into too much detail, a handy rule to use is, if it’s charging via USB, then it will stop charging when it needs to. The device can have a large battery or a small battery, lead-acid or lithium-ion, be a phone or a camera or a flashlight, … if you charge it by plugging it into a USB port, then it has the appropriate intelligence.

      A corollary to this rule is, it’s not enough that the device is capable of charging via USB, you must actually BE charging it via USB. For example, most mobile phones have detachable batteries. You can charge the battery by plugging the entire phone into a USB connection, but if you detach the battery and attempt to charge it via some other means, the rule does not apply.

      Yes, digital cameras … I sympathize … charging a digital camera can be a pain in the butt because most of them require that you remove the battery and then attach it to some external charging doodad. That doodad then plugs into a wall socket, or sometimes into a 12-volt vehicle accessory socket, and either way you can’t use a USB battery pack or USB hub to charge it. Bah!

      My “solution” to this, such as it is, is to use the iPhone camera for spur-of-the-moment shots, and then a fancy Canon camera with a bulky lens for the more serious shots. The iPhone charges via USB, so no problem there, but the Canon has a removable battery that requires a wall charger (yuck). The good news is, the Canon will take something like a thousand shots before I need to recharge the battery, which is plenty of time for me to get to the next bump in the road with mains power. It sucks to haul that charger along, though. I mean, it weighs only about as much as my iPod, but still … it’s the principle of the thing!!

      If you’re going the do-it-yourself route with your camera battery, and there is no USB charger currently available, you are going to need some special circuitry to tell your charger to shut off when it senses that the battery has gone above 3.7 volts. I suggest you look into modifying an “e-cigarrette” USB charger, like this one. “E-cigarettes”, in additional to being foul and bizarre, run off a single 3.7 volt cell. That’s what the ‘model 901’ battery is. By busting apart their little charging unit, you can get the USB connector, all the circuitry, and an LED status indicator, assembled together into a small package, for about five bucks.

      WIth your camera battery thus adapted for USB, the “NC17 iPhone Hub Charger” gadget might suit your tastes. ( ) I’ve never used it, so if you do get it, let me know how it fares. :)

      Your trip sounds exciting. I’d love to tag along. :D


  3. paul cote says:

    Thanks for this True Adventure! Thoroughly entertaining and chokful of useful lore. Hat’s Off to you.

  4. Tom Parker says:

    Holy Cow, Having just skimmed this I can’t wait to waste an entire day savoring your adventure. It is EXACTLY what I’ve been wondering as I ride my bike and now, well, you know when you bump into something and think, Oh boy, this is the perfect evening read for a recliner and a few beers. Thanks for posting this. Amazing.

  5. Mohamad says:

    Awesome article man. You rock! I need some help.

    I live in Miami Beach and love the environment so I decided to make a difference by giving up my car and started using a bicycle exclusively, including the commute to work. Unfortunately my $1600 Cannondale Bad Boy 1 was stolen (thief used hacksaw to cut through 2 inch thick aluminum bar that I locked my bike to with a hardcore Abus “Granit” 6500 lock while it was in the fenced enclosure that surrounds my house – long story short, Miami is filled with scummy thieves that steal everything and anything). I’m undeterred so I’m considering purchasing a Cannon 29er that might be even more expensive than my original bike. I’m not an idiot so I want to hook up a device like spylamp (there is also a seatpost version) or similar so I can track my bike if it ever gets stolen. The only problem is that if the battery runs out before I catch the thief I’m screwed. IS there a way to create a similar device that could be hidden in my bike tube or under seat to charge a GPS tracking device with a bike dynamo? Regards.

  6. Thank you for great article. I couldn’t believe your project will include even 3D printing.
    I am planning a 6000 km bicycle journey around the Baltic sea and I am looking for a similar solution. I hope your USB charging theory applies to Google Nexus phone as well not just to the iPhones. But I am not such a die hard do-it-yourselfer so I will probably go with some factory device.

    I’ve learned a lot from you man. And I really enjoyed reading it. Thank you.

    • Happy to help, and thank you!

      It’s true – if I was going to go through that process again, especially in the year 2013, I would buy a factory-produced device. A small battery pack that I can recharge when I get to my destination has turned out to be more than adequate for my needs, especially since I divert dynamo power to my headlight when night falls.

      There are products now that will charge a device directly from the power of a dynamo hub, without using a battery, but I’ve avoided them for two reasons:

      1. I don’t entirely trust a device with very limited ability to buffer power, when charging my 600-dollar phone. Call me paranoid!
      2. Sometimes I need to charge a device while I’m not on the bike. For example, after hiking all day. The battery pack can do that – the dynamo cannot.

      I always envisioned myself as a kind of rough bicycling survivalist, going up into the mountains or into deep forests far from civilization. In practice, I’ve never been more than half a day’s ride from a power outlet, and even the limited solution I use now has been more than adequate for that…

      Live and learn!

      Your bicycle ride sounds amazing. If I had the vacation time, I’d tag along!

  7. Joachim says:

    I have spent the whole morning reading all sections of this entry. Very joyful and good writing. I can see myself in this; starting up little easy just to end with a huge complex system. I find it fun. And the end involving a 3D printed case is just hilarious!,,

    Thanks for sharing.

    • Yeah, I had to admit, it got way out of hand in the end, but I sure learned a lot.

      Thanks for reading. I hope I’ve inspired you to have your own electronics adventure; and if so, do share it!

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