Northern Tier 2010

June 10, 2010

Busch & Müeller E-Werk: Power on the Go!

Filed under: Gear — Tags: , , , — Henry Scott @ 7:26 pm

Busch & Müeller E-Werk Power Converter (image from B&M)

I built my LHT with a hub dynamo not only to power my front and rear lights, but also because I was intrigued by the possibility of charging other electronic gadgets as well. I’ve been aware of people building their own DIY kits for this purpose for several years, but I haven’t been quite that motivated. In the past year or so, however, a few commercial products have become available — or at least been announced.

The first to catch my eye was the Dahon Biologic ReeCharge. It is essentially a battery that connects to the dynamo hub, stores energy, and has output to power any USB device. However, despite announcements about its imminent release starting in 2009, it has not made it to market as of June 2010.

Although I initially was turned off by its higher price and apparently greater complexity, the Busch & Müeller E-Werk has been readily available for months. It does not come with an integral battery, like the ReeCharge, but it is far more versatile. Whereas the ReeCharge can only output at 5 V and 0.5 A (the specification for USB), the E-Werk can output a voltage ranging from 2.8 to 13.3 V in steps of 0.7 V and a current between 0.1 to 1.5 A in steps of 0.1 A. It comes with easy-to-swap connectors for several flavors of USB, but can be readily customized to other plug styles as well.


Installing the E-Werk is easy. For a Shimano dynamo hub, you simply twist the two E-Werk wires together with the two wires leading to the headlight — the polarity does not matter.

Connecting E-Werk leads to Shimano Dynamo Hub Plug (image from E-Werk manual)

The E-Werk itself is smaller than I imagined, and since it comes with generous wiring lengths, it can be mounted just about anywhere. I currently have mine on the downtube, but I may end up keeping it in my handlebar bag or front pannier.

E-Werk mounted on the downtube of my LHT

The E-Ewerk can be used simultaneously with the bike lights, but I noticed that when I have the E-Werk set to output maximum current (1.5 A) my headlight didn’t just dim: it flickered. I worry that could shorten the life of its LED, so I don’t plan to use them simultaneously unless I’m desperate for some reason.

Storing Energy for Later Use

APC USB Battery Pack (image from APC)

I already had a 10 Wh rechargeable USB battery pack made by APC (UPB10, discontinued) which I can use to store some energy when I don’t have an immediate need or, as I’ll explain below, I need to charge my camera’s batteries. But, most often I’ll simply use the E-Werk to directly charge the batteries in my devices, and this should be more efficient. Specifically, I’ll have a mobile phone, an iPod Touch, an iPad and digital camera batteries. From what I’ve read, some devices, such as the iPhone 3GS, require the use of a cache battery, but I haven’t encountered this myself. I suspect the APC battery pack would work well for such a need.

Cell Phone Charging

I initially thought I’d charge my cell phone (LG Accolade 5600) from the APC battery pack, but for reasons I don’t yet understand that doesn’t seem to work — the phone does indicate that it is charging when plugged into the battery pack (even though it is designed to be charged via USB!). However, by connecting the phone directly to the E-Werk and setting the E-Werk to 5 V and 0.7 A (as specified on the phone), the phone indicates that it is charging once I reach about three miles per hour. Although I haven’t tried charging it from a completely drained state, it went from half to fully charged in well under two hours of riding, so directly charging the phone from the E-Werk seems like the way to go.

iPod Touch and iPad Charging

I have not yet directly connected an iPad to the E-Werk, but I have connected an iPad to the APC USB battery pack, and it indicated that it was charging. Notably, the iPad’s battery has a capacity of 25 Wh, so even if charge transfer were perfectly efficient it would take 2.5 complete charging cycles to restore a totally drained iPad. That said, I expect my daily usage to only be ~10% of the iPad’s battery, so this should not be a problem. A little testing with a friend’s iPad resulted in the iPad going from 80% to 90% charge in a little over an hour when connected to a fully charged APC battery pack. That said, if it works, I’ll probably just connect the iPad directly to the E-Werk.

I’ve charged a 2nd generation iPod Touch both directly from the E-Werk and from the APC USB batter pack, and both seem to work well.

Charging Camera Batteries

Lenmar Universal USB Battery Clip Charger (image from Lenmar)

My camera, unfortunately, can’t simply be plugged in to charge its batteries. Instead, the battery must be removed and placed in a standard wall-outlet charger. However, Lenmar makes a device called the Clip charger (PPUCLIP) that is designed to charge just about any camera or phone lithium-ion battery. It has movable electrodes that one positions to come in contact with the appropriate terminals on the battery. It is a bit awkward, but it is small and, more importantly, is designed for a USB power supply. Using this device, I can charge my Canon S90 batteries with the APC battery pack mentioned above. This is key because I will be taking lots of pictures on this trip.

Charging a Canon S90 Battery from an APC USB Battery Pack via the Lenmar Clip Charger

Preliminary Conclusion

I still need to do more testing, but so far I’m quite impressed with the E-Werk. I’m optimistic that I’ll be able to get all of the electronic power I’ll need for my trip this way. From what I’ve observed so far, it seems that five or six hours of daily biking will more than meet my electricity needs.

I should acknowledge, however, that this would not be an economical solution for most. I bought my E-Werk from Starbike in Germany, and it was about $130. That’s in addition to the cost of the dynamo hub, but I’d argue that the dynamo hub is justified purely for the lights. Still, $130 could buy a lot of batteries, and one could of course just keep an eye out for outlets and plug in during restaurant meals, grocery shopping, etc.

I can’t really argue that this is particularly green, either, because my impact would be much less if I simply did without all of the gadgets. Ultimately, this is largely a novelty, but I do think it will be an interesting experiment to see if I can complete the entire tour without ever having to “plug in.” Finally, even when small steps such as this don’t directly pay off environmentally, I have little doubt that the personal awareness they raise about energy usage will lead to smarter choices in the long run.



  1. Hi Henry,

    Very informative review. I also bought an E-Werk in Nov/09 which I used for a recent tour of South America. Just a heads-up regarding the rubber band used to secure the E-Werk to your downtube. After less than 6 weeks on my bike, the rubber band dried up, cracked and snapped. Luckily I had some small zip ties which were perfect to secure the E-werk to my top tube. Good luck on your tour!

    Comment by Ray — June 27, 2010 @ 12:13 am

  2. Thanks for the heads up! I have a pocket on my right front pannier — perhaps I’ll just keep it there.

    Comment by Henry Scott — June 27, 2010 @ 11:28 am

  3. Hi Henry — I have really been enjoying your blog. I especially love the gear posts. This charging setup is awesome!

    Comment by Sarah P — August 2, 2010 @ 7:32 pm

  4. Hi Henry — I’m thinking of getting an E-werk so your information and Ray’s comment are both very helpful. Something I would add on the cost discussion is that although one could go with charging at restaurants etc, that’s always a hassle and a time-waster and may even raise a risk of theft unless you sit beside your device as it charges. With a dynamo charger, as long as it works, I could travel freely, never be caught without a charge, and never have to plan my day around the location of an electrical outlet.

    Comment by John — August 10, 2010 @ 3:05 pm

    • Good point. I met a guy during this trip who had his cell phone stolen while it was charging in a bathroom.

      I think today is my 34th day on the road, and I have yet to plug anything into a wall outlet — that includes cell phone, camera batteries and the iPad (and the iPad is getting a lot of use!)

      Comment by Henry Scott — August 10, 2010 @ 6:03 pm

  5. I have just purchased the Ewerk and I was wondering if you have been able to charge an iPad directly on it without the cache battery?

    Comment by api — August 21, 2010 @ 6:01 am

    • I only tried it once, and it did charge, but my sense was that it was very slow. I’m not sure why; in fact, I wouldn’t be surprised if, perhaps, I just didn’t give it enough time or I had the current setting too low.

      However, I haven’t tried it again because I feel more comfortable charging the battery during the day and using the battery to charge the iPad at night. This way I can have the iPad safely packed away while biking. The battery is so small I can easily just keep it in my handlebar bag. Charging from the battery is surprisingly fast — apparently the APC battery I use can put out relatively high current. The fully charged APC battery can provide about one third of the iPad’s battery capacity — enough for at least two hours of usage per day.

      Comment by Henry Scott — August 21, 2010 @ 12:06 pm

  6. I used the Ewerk (5.6V 1.5A) with the battery for several months with the iPhone 4. Occassionally it alerted me with a message “Charging is not supported with this accessory.” It would not charge the phone at all after the iPhone software was upgraded to 4.2. The Ewerk and battery work fine for my 60GB iPod. Suggestions, please.

    Comment by Jim McCreight — March 31, 2011 @ 3:34 am

    • That’s too bad… which battery are you using? Have you tried lowering the voltage to the next lowest setting? Or, and this may be a long shot, but perhaps try connecting a portable USB hub to the battery, and then the phone to the hub. I’m afraid I don’t have experience getting around your problem, but those are the first things I’d try.

      Comment by Henry Scott — March 31, 2011 @ 5:42 pm

      • Using the Busch & Müller cache battery. I lowered the voltage from 5.6 to 5.0, which enabled charging last night (1 hr), briefly this morning (20 min) and cycling to the office (25 min) then at 1:30 PM it wuold not charge. Same series of messages and no charge icon. Puzzling. wrote to B&M, but no response after nealry 3 months; will follow-up. Still charges the iPod.

        Comment by Jim McCreight — March 31, 2011 @ 9:27 pm

  7. The iPhone 4 and iPad need a consistent flow going to them or they will give the dreaded Charging not supported. I am also getting a dynamo hub and the Ewerk but I plan to get an Apple approved battery backup and charge that. Many of the approved backups will take a charge and give at the same time. Yea it is an extra gadget to carry but the backup would be great foe other things as well during the night.

    Comment by Pirate Velo — May 19, 2011 @ 11:41 pm

  8. its is possible to conect the ewerk to the xpal energi to go like a cache batery?

    Comment by rafael — June 19, 2011 @ 6:32 pm

    • I don’t see why not, but I haven’t tried it. Is this the model you’re considering?:®-XP1000-Universal-Rechargeable-Power/dp/B002K8OQWS

      If so, it doesn’t have a lot of capacity. It is rated at 1,000 mAh. At five volts (USB spec) that’s 1Wh of total energy storage, which is only 10% of the battery I used. But, if that’s all the juice you need, it should be relatively easy to get it fully charged with the E-Werk.

      Comment by Henry Scott — June 20, 2011 @ 4:02 pm

  9. Thanks for the useful info.

    When you say you try not to use the e-werk and lights at the same time, do you physically disonnect the e-werk from your dynamo, or just not have any device plugged into the e-werk?

    Also, do you have any idea whether a garmin edge 605 will work directly off this?

    Thanks again

    Comment by urban_gibbon — July 16, 2011 @ 1:26 pm

    • I just disconnect the device, but I leave the E-Werk connected. I’m pretty sure that when no device is connected, the circuit is open, and not current will flow.

      I’m sorry, but I don’t know about the Garmin Edge. However, it looks like it takes a standard USB mini plug, so I don’t think it would be a problem.

      Comment by Henry Scott — July 20, 2011 @ 9:29 pm

  10. This is what Apple say about charging peripherals including iPad, iPhone etc

    The basic charging setting is 500 mA (Milliamps) at 5 V (Volts) but Apple say peripherals may draw up to 1100 mA at 5 V under certain conditions so may require Ewerk to be at this setting to avoid the “not charging” issues

    Comment by Steve — August 29, 2011 @ 6:45 pm

  11. Hello and thank you for this article.In the wiring description you say twist the E-WERK wires together,but all I can see in your photo are two connectors protruding from the top.Do you in fact mean the dynamo light wires?Also could you provide a wiring diagram from the whole set up?

    Well didn’t you get the E-WERK cheap?It’s £140.00 in the United Kingdom!

    Comment by Karl Bike — June 10, 2014 @ 8:10 pm

    • By the following, I didn’t mean to twist the E-Werk wires to each other:

      “you simply twist the two E-Werk wires together with the two wires leading to the headlight.”

      I’m sorry for not being more clear, but what I meant is that one of the E-Werk wires gets twisted together with one of the wires from the headlight, and the other E-Werk wire gets twisted together with the other headlight wire. What makes it easy is that it doesn’t matter which E-Werk wire goes with which wire from the headlight.

      I don’t have a wiring diagram, unfortunately, but I didn’t do anything different from the standard configuration, so I’m sure you can find one online somewhere.

      Comment by Henry Scott — June 10, 2014 @ 8:32 pm

  12. Hey Mate. I have a question about charging your APC battery bank. What settings did you have the E-Werk on as most battery banks have 5v 2.1A max input. Cheers, Sean

    Comment by Sean Conway — June 13, 2017 @ 4:26 pm

    • I’ve only ever used the E-Werk for USB devices, including that battery pack, so I always had the voltage set at 5 [V]. Regarding the amperage, I forget where I actually set it, but I’m pretty sure it was at the maximum possible… even though I’m sure that would imply more power than the hub and E-Werk were able to actually provide. (That is, I tried to make it so the E-Werk would deliver as much current as was available to avoid my setting being the limiting factor.)

      Comment by Henry Scott — June 15, 2017 @ 12:34 pm

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