Biologic ReeCharge: A Dynamo-Powered USB Charger for Smartphones & More

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Tern Link P24h: Reecharge power pack 2

Since the start of this year I’ve been making extensive use of a nifty on-the-road power solution from Taiwanese manufacturer Biologic called the ‘ReeCharge’. It’s billed as an effective — and environmentally respectful — way to put your pedalling efforts to use in keeping your smartphone, GPS or other USB-powered device charged while on the road.

I’ve given it a thorough road-test over the last few months (mainly while riding the Tern Link P24h folding tourer), and I’ll be talking in-depth about my experiences with it in this article. I’ll also talk about a couple of unusual alternative solutions I’ve come across along the way.

This piece will be of interest to anyone who regularly spends more than an hour or two on a bike and is looking for a way to keep their electronics up and running throughout, though I’ll be looking at it primarily from a touring perspective.

Who needs USB power on a long bike trip?

Well — nobody. People have been touring for decades without a whiff of technology to help them along the way. Nobody needs a GPS or a smartphone or an MP3 player or a compact digital camera or a GoPro. And even if they bring such devices along, so much of bike touring is spent off the bike that a simple mains charger is adequate in a great deal of cases.

Please bear with me while I reiterate annoyingly that a big trip, especially your first, will be all the better for cutting loose from these modern distractions. I spent three and a half years on the road without a GPS, a smartphone, or even a normal phone. I didn’t carry a laptop. Most of the time I didn’t have a map. I was utterly reliant upon my senses and initiative to find my way, and if something went wrong (which it often did), it was up to me to find a solution. This was an utterly invaluable learning process. Keep it simple. You don’t need any of this stuff.

But, for one reason or another, you have decided that you’d like to try taking one or more such gizmos with you. Of these, the most obvious beneficiary for a constant on-the-road power source is the GPS, or GPS-enabled smartphone, so I’ll look specifically at that application in this article, though I’ll cover as broad a range of other devices as possible.

Navigating to another screening

Personally, I’ve been making use of a GPS this year in order to navigate between film screening gigs. Because schedules do matter in this case, I’ve been able to use a GPS to travel new roads in a predictable timeframe and on a relatively direct route, which are the kind of circumstances under which the real benefits of the GPS lie when on tour.

What does the ReeCharge system consist of?

Biologic manufacture a range of complementary products — generator hubs, power packs, phone mounts and other accessories — with the idea being that you mix and match depending on your specific requirements. At the core of the system, however, are the ReeCharge Dynamo Kit and the ReeCharge Power Pack.

The ReeCharge Dynamo Kit is the keystone, taking a current from a dynamo hub (a.k.a. generator hub) and converting it into a safe and stable power supply for a USB-chargeable device. It’s a small and unobtrusive little device which straps to a fork leg and requires no further attention in order to do its job.

(I’ll cover dynamo hubs in detail elsewhere, assuming for the purposes of this review that this prerequisite is in place, but it’s worth mentioning that Biologic make a very efficient and affordable dynamo hub, ideal as a foundation for new front wheel builds, called the Joule 3, which I’ve also been testing and will review later.)

While it’s possible to use the Dynamo Kit alone to take a power supply direct from the source to the device, the ReeCharge Power Pack is designed to complement it and fill in a variety of gaps when you aren’t pedalling (at a junction, on a break, for the night) and want to prolong the power supply. It acts as an intermediary, taking the current from the Dynamo Kit and storing it for later use in a built-in lithium polymer battery — in effect, an offline back-up power source. We’ll look at where this comes in useful later on.

ReeCharge Power Pack with connectors

I’ll be reviewing these two complementary products — the ReeCharge Dynamo Kit and Power Pack — together, as it’s only when used in tandem with each other that the genuine benefits of the system become clear. When you buy the Power Pack, you’ll also get the Dynamo Kit in the box, though the latter is available separately.

Who is the ReeCharge designed for?

While I have much to say on the topic of over-equipped, over-technologised adventures, it’s a fact that many bicycle travellers these days are packing smartphones, GPS units, e‑readers, compact digital cameras and other electronic gadgets.

Smartphones in particular are becoming a popular choice for navigation, simply because their built-in GPS systems and the software freely or cheaply available to use them has caught up with standalone GPS units.

In fact, it could be argued that a well-configured smartphone makes for a better navigational tool than a GPS unit because it gives its user the ability to multitask and to use a constant 3G/4G internet connection for route calculation, modification and even logging via apps such as MapMyRide (Android / iOS App*) or TrackMyTour (iOS App*).

The problem, of course, is that smartphones suck up battery power, particularly when GPS and data connectivity are in constant use and the screen and backlight are permanently powered up. You’d be lucky to get a morning or afternoon’s worth of use from a smartphone in this way. The result is coming to the end of your ride with a dead battery. If you’re on tour and camping is your staple overnighting method, this is a real issue. And herein lies one of the ReeCharge system’s greatest benefits.

Imagine setting off in the morning with a detailed, up-to-date digital map with which to navigate all day, and knowing that even after the five or six hours pedalling and navigating and all the breaks you took along the way, your smartphone or GPS unit will still be on 100% charge — AND that you’ll have a fully-charged backup power source with which to top up the batteries of your e‑reader and digital camera that evening from the comfort of your tent.

Navigation of the smart variety

A system like the ReeCharge, which delivers all of this through the simple process of flicking a switch and pedalling all day like you would do anyway, theoretically has the ability to shift the daily routine of a gadgetised touring cyclist to one that no longer includes the constant worry about batteries running out, nor the extended lunch breaks and awkward conversations with restaurant proprietors about plugging a raft of stuff in to charge. If all goes to plan, you’ll have power all day for your navigation device, be that smartphone or standalone GPS, and a way to charge your other bits and bobs in the evening, even when you’re camping for days or weeks on end.

(A word of warning: no traveller should ever rely entirely on electronics. A smartphone or GPS unit is no substitute for a map and compass — and, more importantly, an awareness of how to function comfortably and calmly in a world in which all these modern conveniences are absent. I mean this. If you can’t navigate on wits alone, and your loved ones can’t go for more than a few hours without hearing from you, you really need to stop reading and resolve this first.)

What’s included in the Biologic ReeCharge Power Pack kit?

(This refers to the kit available from Evans Cycles*, who are Biologic’s primary UK stockist.)

You get the Power Pack and the Dynamo Kit. But it’s the cables and adapters that make the difference as this is what determines the system’s real-world usefulness in conjunction with your own devices.

On this front, the following are included in the box:

  • Retractable device cable (onto which you fit the relevant adapter)
  • Apple connector (into which you plug your original Apple cable)
  • Sony Ericsson adapter
  • Samsung adapter
  • Late-model Nokia adapter
  • Mini-USB adapter (almost all your generic USB devices, including GoPro, many cameras, e‑readers, etc)
  • Micro-USB adapter (many Android phones including HTC)

Theoretically it’s possible to plug any other proprietary USB charging cable into the Apple connector and have the device charge up too, as the power pack outputs a standard 5V USB supply for up to a 850mA current draw.

There is also an innocuous looking piece of transparent rubberised silicone in the box. Far from being simply a disposable part of the packaging, as I originally thought, this is actually an ingenious shock resistant handlebar mount for pretty much any handheld device in dry weather. I’ve used it with a couple of smartphones and a GPS unit and it’s possibly my favourite part of the whole kit.

How do you set up the ReeCharge?

The Dynamo Kit consists of a power regulator with cables to connect it to your dynamo hub at one end, via a standard power connector, and to the Power Pack at the other.

ReeCharge transformer

It’s designed to work with sources outputting a standard 6V at 2.4 or 3.0 watts. For the sake of completeness, that includes not just Biologic’s own Joule II, Joule 3 and Joule HG hubs, but also the Schmidt range of uber-fancy SON dynamo hubs, SRAM’s D7 and D3 hubs, Shimano’s current DH-3N80 and DH-3N72 hubs, and the SunUp Eco DS1‑R, which you haven’t heard of but which I’ll mention later on.

A dynamo hub is the only pre-requisite for using the ReeCharge system. Some trekking, touring and city bikes, especially from continental Europe, will have these as standard. Otherwise, it’s a chat with your local bike shop’s wheelbuilder, or of course the DIY wheelbuilding option.

(And even that’s negotiable: I decided to see if the system would work using an old-fashioned bottle dynamo. Did it? Yes. This is officially supported by the manufacturer, if you’re wondering.)

Having hooked up the Dynamo Kit to the hub, the other cable connector mates with the ReeCharge Power Pack. This features a rugged silicone casing into which is built an adjustable mounting strap. The idea is that you can strap the thing to your head-tube or stem, but easily disconnect the cables and take it with you in order to use it as a power pack. You’re expected to stow the cabling as you would for a cycle computer, either by wrapping it around other bits or cable-tying it to the frame appropriately. Not exactly rocket science.

ReeCharge on the Challenge Hurricane

Having done this, the input and output connector ports face downwards, which together with the weather-proof seals concealing the Power Pack’s connectors is how all of this stuff stays functional in a downpour. Orienting the Power Pack towards the direction of travel also allows the battery indicator LEDs (thoughtfully, white) to be used as emergency visibility lights. Nice touch.

All that’s left to do is mount your chosen device to your handlebars via the method of your choice, choose from the range of connector adapters (mini USB, micro USB, Samsung, Sony Ericsson and new Nokia — Apple users can use their own cables), plug up, and you’re ready to go.

Tern Link P24h: Pedal-powered GPS & front light

Though a clever little wraparound silicone universal device mount is included in the package, it’s not exactly going to weatherproof an expensive smartphone. Biologic make their own weatherproof handlebar mounts for the iPhone and a selection of Android smartphones. I’ve yet to try any of these myself, preferring the silicone strap method, the rubber band method, and not cycling in the rain.

Tern Link P24h: Dynamo-powered navigation

It’s all pleasingly uncomplicated, even if there are quite a lot of cables to fiddle with, especially if you’re already got a cycle computer and a dynamo-powered lighting system on the go. But hey, that’s what cable ties are for. No extra marks available for presentation.

How does the Reecharge perform in real life?

For the sake of realism, let’s amalgamate all of my experience with this unit (almost a year of regular use) into a single hypothetical day on the road and overnight camp.

I mount my phone on the handlebars, plug in the power input cable with its appropriate connector, and fire up my navigation app of choice (Backcountry Navigator, for the sake of example).

I attach the Power Pack to the head tube with the quick-release strap, plug in the power input cable from the dynamo, plug in the power output cable alongside it, and switch on the unit’s power input mode. Now, when I begin pedalling for the day, I’ll see a green LED illuminated on the side of the unit, which indicates to me that it’s receiving power and therefore charging its internal battery. I check the level of the battery by giving the middle button on the power pack a quick press, which illuminates between zero and three white LEDs to indicate the remaining charge.

Tern Link P24h: Reecharge power pack

If the unit is fully discharged (for example because it’s been used to charge up several other devices the previous night), I’ll probably ride for an hour in this state to put some juice back into the power pack. I’ll run the phone or GPS on its battery during this time. This is because, when the pack is discharged, there won’t be a continuous power source to the device in the case of stopping the bike. Give it a little charge, however, and the unit will continue providing power to the device when I stop the bike by switching to its internal battery. Stable and continuous power is generally a better idea for maintaining longevity with lithium cells (i.e. those used in almost all modern USB-powered devices) than short, broken bursts of charge.

If there’s some charge present in the pack already, however, I can switch on the power output immediately. Now, my device is running on external power via the ReeCharge. While I’m pedalling, this will be coming directly from the dynamo, via the power pack. If I stop for a break, or at a junction, or whatever, power will continue to be supplied by the pack. Additionally, if the current required by my device is not onerously high (though with the meatier smartphones it may be), the power pack will gradually gain charge at the same time.

The long and short of it is that my navigation device will be externally powered, and having its own battery charged, during the course of my morning’s riding. The ReeCharge Power Pack will likely be getting some charge as well. And I won’t have to worry about switching everything off for short breaks in riding, because the backup power supply will kick in automatically.

Tern Link P24h: Riding

By lunch, my device should be approaching full charge, if not already there. (There’s a mains power adaptor included, by the way, which might well be used at lunchtime to top up the power pack if the facilities are available.)

In a rigorous and highly controlled test, I take a HTC Desire HD — a notoriously power-hungry smartphone — and charge it from 7% charge to 50% in one morning of riding. This was using an inefficient bottle dynamo, with the phone’s GPS function switched on and with MapMyRide and Backcountry Navigator running simultaneously. With a modern hub dynamo, better results will be obtained. (Note that I did have Flight Mode on to disable the 3G network connection, which is not exactly necessary when you’re pedalling.)

When it comes to lunch and thus a longer break, I’ll switch off the power output of the power pack. This has to be done manually using the same switches, and the change will be indicated by the red LED turning off.

And this is where I run into one of the unit’s few (and luckily minor) flaws. You see, accurately reading the state of a tiny red LED in the direct light of the midday sun is impossible. I have to cup my hands around the unit and squint in order to make out whether it is on or off. Not just that, but the buttons on the front are ambiguous in their state — by which I mean there is no positive feedback, visual or tactile, to indicate whether a button press has resulted in the unit being switched on or switched off.

The same is true for the power input switch, and the green LED is even less visible than the red one. And since the only way to illuminate the green LED is to have the dynamo create a charge, I soon find myself in the awkward position of trying to lift the front wheel off the ground with one hand, spinning it with the other, and then rapidly cupping my hand around the power pack in order to see whether or not the green LED has come on — by which time, once I’ve got the angle right and blocked out enough sun, the wheel has stopped spinning. (Riding the bike whilst bending down below the handlebars is obviously not recommended.)

These are minor problems. There are workable solutions, and they don’t impede the core functionality of the unit. After a lot of use, I have become sensitive to the buttons to the point at which I can tell their state by pressing them, but it’s a very delicate discernment to make. There is also the more reliable method of plugging a device into the Power Pack and seeing how it responds to a press of the relevant button, as almost all devices will indicate clearly whether or not they are receiving external power. Lastly, on overcast days and in the mornings and evenings (and at night, should you fancy it), making out the LEDs is not half as difficult.

But it is something Biologic might note for future incarnations of the design. There’s no point wasting power on LEDs, so my suggestion would simply be using switches that provide unmistakeable feedback as to their on/off state.

Once fully charged, any modern device will only draw enough external current to keep itself powered up with the battery remaining at 100%. Thanks to the ReeCharge Power Pack’s smart circuitry, this surplus pedal power will be used to charge its own internal battery. The result, at the end of the day’s ride, is likely to be a fully-charged device ready for the following day’s ride, and/or for a little communications use in the evening in the case of a smartphone — AND a more or less fully charged power pack. This is where we get to see the beauty of the intermediate power pack system.

Arran sunrise panorama

I’ve removed the power pack from my headtube by unplugging the connectors and undoing the quick release strap. At this point, of course, I’m probably in my tent/hammock/mosque/drainage pipe, getting set up for the night. Here’s my opportunity to use that stored-up pedal power to top up my other devices.

Let’s say I’ve got a GoPro mounted to my handlebars, and I’ve drained the battery in the mistaken belief that anyone else will be interested in watching countless hours of nondescript asphalt going past in slow motion. Will the ReeCharge be able to, er, recharge said camera in order that I may tomorrow film more of the same?

The answer is yes, as demonstrated by another rigorous test in which I plug a fully discharged GoPro HD Hero into a fully charged ReeCharge Power Pack and hit the power output switch. It takes 2 hours and 15 minutes to fully charge the GoPro, leaving enough juice in the Power Pack to get other mission-critical systems up and running again the following morning. (It’s worth mentioning that a realistic day’s filming routine would only drain a GoPro completely if there was an extremely long timelapse or accidental button-press involved.)

How about if I’ve got a drained smartphone on my hands?

ReeCharge with HTC Desire HD 1

In yet another real-world test, the same HTC Desire HD is charged from 3% to 70% by a fully charged power pack.

ReeCharge with HTC Desire HD 2

A Nook Simple Touch e‑reader’s battery is similarly taken from 40% charge to 100%, using less than half of the Power Pack’s capacity in the process.

ReeCharge with Nook

(E‑readers like the Nook*, of course, can last weeks on a single charge, and when hacked to offer basic Android tablet functionality can be very handy and extremely inexpensive things to pack for a bike tour.)

Bear in mind that this is all after having charged and powered a navigation device for the duration of my day’s ride. I am hoping that these examples of real-life use will be sufficient to give a clear idea of the system’s capabilities, though your mileage will of course depend on which and how many devices you use, as well as how you use them.

While I have not tested the unit in laboratory conditions, nobody actually goes cycle touring in a laboratory, and those who test equipment in such a way are usually better authorities on life in a laboratory than life on the road.

Just saying.

What about dynamo hubs and ReeCharge compatibility?

None of this is any use to anyone who doesn’t have a dynamo hub (or plain old bottle dynamo). In the UK, it’s fairly uncommon to get a new bike with one of these fitted as standard, except on city bikes for which they’re sometimes fitted for powering lights.

What this means is that you are quite likely to end up looking at aftermarket generator hubs, rather than gleefully plugging the ReeCharge into your existing, underused dynamo hubs. While I can only personally speak for the effectiveness of three of these hubs, all of the ones I’m going to list here will in theory do the job, and there’s no reason to think they wouldn’t. Some will do the job more expensively than others. of course. And on a fully-loaded touring bike it is highly unlikely you will notice any additional rolling resistance from any of them.

If you really want to read more about current output and efficiency figures and stuff, the CTC’s Cycle magazine recently published this article, which takes clinical empiricism to a whole new level. (Don’t say I didn’t warn you.)

Most local bike shops will be able to build a complete wheel onto your hub — a good opportunity to specify rims at the same time. Sun Ringle CR-18s* are a good choice for 26″ wheels.

Biologic Joule 3 Dynamo Hub

Biologic Joule 3 / Joule HG

The Joule 3 is a relatively new offering from Biologic, designed with the Schmidt SON Dynohub (the Rolls Royce of generator hubs) as the performance and efficiency benchmark. Available in a 100mm OLD / 32-hole model, it’ll suit all but the most paranoid and heavyweight tourers who absolutely insist on 36 spokes per wheel. I’ve been using this all summer and it’s the hub I’ve used for most of my testing for this article. The Joule HG is an older model that can be switched off mechanically, virtually eliminating drag. They retail at around £120. It’s a shame they seem so difficult to source in the UK. I can’t even find them on eBay*.

Shimano DH-3N30 Dynamo Hub

Shimano Budget Dynamo Hubs

Shimano, eh? They don’t half make it difficult for us. Five billion permutations of the same thing, whichever direction you turn. Their budget options for generator hubs are the DH-3N20 and DH-3N30. They will work with the ReeCharge. They might break sooner than the pricier ones. (Or they might not.)

Shimano DH-3N80 Dynamo Hub

Shimano High-end Dynamo Hubs

The current established high-end Shimano models are the DH-3N72* for rim brakes (~£70) and the DH-3N80* (32h/36h) for disc brakes (~£90). They’ve been widely used and can be considered tried and tested on tour. Shimano have just released another billion new variations under the XT line, but it’s probably best to ignore them until the market settles down again.

Schmidt SON 28 Dynamo Hub

Schmidt SON Dynohub

If you just can’t help yourself, the German-made Schmidt SON Dynohub enjoys a reputation as the hands-down best dynamo hub money can buy. Why you’d blow £200–300 on one is beyond me, but I’ve included it here for the sake of completeness. SJS Cycles have them, if you really must.

And now for something completely different…

I was introduced to the SunUp Eco DS-1R dynamo hub in Taiwan last year, and I have taken it for a series of test rides since then. The big difference with this rather innovative generator hub is that it can be fitted to an existing rear wheel with no modification — thus, no wheelbuilding. It outputs 6V at 3.0A, just as the Shimano and Schmidt offerings do. The only caveat is having to undo a single hex bolt in order to remove the rear wheel, though it’s hardly a deal breaker on a long tour.

SunUp Eco DS1-R

You’ll be hard pressed to find one in a shop here, but thankfully they are available direct from Taiwan via eBay* for just under £80, including postage.

In Conclusion

If you’re dreaming of your first big adventure: forget all of this rubbish, get a bike and leave already. Here are the 3 basic steps. Keep it simple. Enjoy.

If you’re absolutely sure you want to get into all of this gadgetry, and you’re looking for a reliable, versatile power solution compatible with all popular dynamo hubs and the kind of devices you might take on tour, the ReeCharge system performs this function and performs it well. It’s not 100% perfect, but minor niggles can be overlooked given its simplicity and effectiveness in getting the job done.

In the UK, I’d head to Evans Cycles’ website* to get mine. They’re currently doing it at 10% off — and yes, all the accessories mentioned in this article are included. (Not the hubs, though.)

In the USA, Biologic’s outlet stock the ReeCharge.

Comments (skip to respond)

42 responses to “Biologic ReeCharge: A Dynamo-Powered USB Charger for Smartphones & More”

  1. Hey Tom,

    I was just skimming this article while trying to find some information on the Joule HG. I’m wondering if you ever had a chance to try it? It is very difficult to find information on. There do not seem to be any other on/off dyno hubs on the market. I’m am curious about its quality. Any insight would be appreciated.



    1. It was fitted to the Tern Link P24h which I rode around for several years. It powered a couple of lights and a ReeCharge power pack. Never had any problems with it – good build quality and very reliable in my personal experience. Hope that helps!

      1. Thanks Tom,

        That is reassuring. Did you notice a big difference in the resistance when it was disengaged? My wife and I are getting our gear together for a Pan-American ride. Would you feel confident enough to take it from Alaska to Argentina?

        1. No, I didn’t notice much difference. Actually I visited the company in Taiwan a few years back and they mentioned that it was among the lowest-resistance generator hubs on the market. I would indeed feel confident touring long term with it, but as with all technology, I wouldn’t rely on it completely.

  2. I just built up my kit based on your article. I bought the wheel parts and built a shimano dh-3n72 dyno hub wheel for $130. I bought the dyno kit and recharge pack basic for $85 (including shipping) from Premium Bike.

    Works great !

  3. […] This allows me to simply enjoy my ride. The only problem is the battery life of your phone. Here is my preferred option for staying charged on the road. It is appreciated when those developing the maps produce these files and share them on their […]

  4. Another excellent USB power provider is the D1. It has an excellent spec as seen on it’s website and looks more robust than anything else I’ve tried, including the B&M Werk which failed for me on a trip. Check it out:

  5. Andrew Norris avatar
    Andrew Norris

    Hi Tom. You said the DH-3N80 is for disc. This is actually not true. The ‘N’ means normal = rim only. The DH-3D80 is for disc. as is the DH-3D72. D = disc or tim. Only difference between the 72 and 80 models is the axle type which saves a few grams. The DH-3D80 is identical to the XT — and is often sold cheaper! 72 and 80 models feature Shimano’s best labyrinth and contact seals. As good as dura ace ! Make sure bearing tension is spot on with Shimano hubs — they often set it too tight in the factory. The Son models are not that much more efficient over shimano to justify the cost. 1w difference with lights off is NOTHING. And not much between them with lights on too! 

    The number immediately after the DH, is the watts it produces based on German regulations. DH‑2 means 2.6 watts (front light german regs) dh‑3 means 3 watt (front & rear light german regs dh‑1 means 1.5 watt — flashing lights only front/ rear — german regs)

    1. Andrew Norris avatar
      Andrew Norris

      PS. I meant the shimano hubs generate 1W extra drag with lights off at 10mph. This is nothing! (This is not to be confused with the power the dynamo puts out).

    2. Thanks for the clarifications!

  6. A 1 pounds buck voltage converter will do the job perfectly ( and you won’t have to make it yourself :). Jailbroken iphone users can download an app called Beep Beep and it will allow your phone not to respond in any way to the start of charging. This will save a lot of juice as iphone turns the screen on and vibrates when charging starts. The battery way is a good option, but you loose 30% efficiency. Hopefully this will help for the people who are on a tight budget and iphone users

  7. […] of strapping a dynamo to your back tire to power a light for nighttime cycling. Devices like the Biologic ReeCharge and Tigra Sport Bike Charge Dynamo Light & USB Charger are designed to either replace or […]

  8. terrific information. am just getting psyched up for a ride through north, central and south america. one question nags me as I read and learn from Tom… that is : what does one do or not do when storing ones ride (bike + peripheral gadgets) to sight see, relax, take A break from riding, etc.

    any tips on safe bike and gear stowing in remote and non remote environments?


  9. Jaap Mosselman avatar
    Jaap Mosselman

    Hi Tom, do you have any experience with attaching the ReeCharge Dynamo Kit directly to a smartphone (Nokia Lumia 520 in my case)?
    I see that the loading indicator is displayed for some seconds and then the battery locator is displayed again for some seconds.
    My bicycle has a dynamo hub Shimano DH-C6000-R2‑N (6V‑2.4W).
    Or do you advise to use a power pack?

    1. Definitely use the powerpack!

      1. I used the Reecharge unit briefly after my initial dynamo install but quickly decided that I wasn’t getting the maximum current output from the regulator due to its inexpensive construction. I have since upgraded to a AXA Luxx50 nano light with built in USB charger and an inexpensive chase battery. This setup keeps my phone (Samsung Galaxy S5) charged. Without the chase battery..(any battery that can be charged and discharged simultaneously) the phone wont charge unless I’m riding at some ridiculous speed! If you notice your battery indicator flickering on and off, this is probably the same issue for your setup as well. The Reecharge battery wont do that so you are either charging your phone or battery but not both at the same time. The Supernova Cinq5 and the Bikecharge powerpack are a few that can. I am using a Mycharge battery I purchased at Target that works as well, its just not waterproof. Should I decide to tour with it, I’ll upgrade to one of the batteries mentioned above. I hope this helps.
        I provided a link to my dynamo building blog experience.

        1. oops, looks l like my link didn’t show.


        2. Jaap Mosselman avatar
          Jaap Mosselman

          Thanks for the info. Would a myCharge AmpMini satisfy?
          Unfortunately myCharge seems not to be available in NL or EU shops.

  10. Hi Tom

    A very good review of this great little device. I have had a Reecharge now for a couple of years coupled with my Schmidt SON dynamo on a tandem. We have toured extensively with it, and my lists of pro’s and con’s are as follows:

    — The unit has a good construction which seems to be pretty waterproof and rugged
    — The unit charges even at quite slow speeds and provides a really good charge
    — easy to fit and to use
    — very good value compared to the alternatives
    — you can use the three LEDs on the front as an emergency front light!

    — We noticed very quickly that the cable to the power regulator was quite poor quality. On my unit this cable split easily where it was rolled up (as too long for most bikes). I have had to use heat shrink and tape to cover up the splits and repair it.
    — The power regulator will be destroyed if you are charging from the dynamo but do not attach the ReeCharge (or haven’t pressed the input button). I have had to repair this regulator after it overheated after accidentally not turning the input button on.
    — As you highlighted the green input is very difficult to see in any sort of sunlight and is difficult as you say to check. I wondered why they didn’t just not have an input button and make it charge always if plugged in.
    — my wife got a new phone (Sony Xperia Z1) and unfortunately the ReeCharge unit didn’t charge it so there must be an limit to certain devices — but you can’t really blame ReeCharge for this. Every other phone I have tried like the Samsung Galaxy S2/S5 do charge. Just something to be aware of.

    So in summary, a great unit but let down by a poor quality cabling and power regulator. If they could fix this aspect of it it would be a very good option and highly recommended.

  11. First off, love the service this site is providing:-)
    I want to share that you must deduct the weight of the required items of the wheel that would be in it anyway before you can say the dynamo hub is heavy. I.E. bearings, cones, longer spokes and the basic hub housing to hold it all together.
    I have also heard that the bearing system on the Schmidt hubs are extremely well made and durable.
    Food for thought.
    Dave from Alaska

    1. Already took that into account in my comment, I just didn’t include the working. I’ve included it below since you asked. In the case of the DH-3N30 the saving is about half a kilo.

      XT M770 non-disc front hub including quick release 217g
      Busch & Muller Dymotec 6 206g
      Basta turbo ~120g
      Basta trio 160g
      SON Delux allowing 60g for quick release 450g.
      Shimano DH-T785 incl quick release 560g
      DH-3N30 incl. quick release 827g

      PS: A dynamo hub typically has a larger flange so the spokes will be shorter and will weigh a few grammes less in total, but this weight difference is negligible compared to the above items. Some might say that even half a kilo is negligible but if I’m climbing mountains, every little helps.

  12. I wouldn’t recommend anything other than the very highest quality bottle dynamos for extended touring, and even so make sure you carry spare wire, spare drive wheels, and tools to fix it.

    I used to run Basta and Union bottle dynamo systems on my touring and commuting bikes. They are great when they are working, as they are light, powerful, and there is no resistance when off, but there are many problems:
    — the shaft of the dynamo spins very fast so the bearings must be of excellent quality if they are to last
    — the bearing problems are exacerbated by very high speeds (e.g. descending mountains where you might think it is a quick way to charge your batteries).
    — the wiring is flexed by the initial and constant movement of the dynamo whilst in contact with the wheel so it will inevitably get fatigued and break
    — The dynamo and wiring are exposed to the elements being very close to the rim and often close to the brakes where spray and ground-up brake compound blended with water will come into contact with the dynamo
    — the drive wheel of the dynamo that touches the tyre wears out and loses grip, and might come off
    — the contact surface of the tyre wears out. It is necessary to use tyres that are designed for bottle dynamos such as Schwalbe Marathons. Other tyres’ sidewalls may wear out prematurely as a result
    — maintaining adjustment of the dynamo on the tyre can be difficult, and annoying
    — Even a well-adjusted dynamo may lose grip on the tyre in wet weather where you need the light the most. This is not serendipitous, and can become very dangerous if riding in both the dark in wet weather

    All these issues are avoided with hub dynamos. 

    The downsides of the hub dynamo are the cost, the fact that you may need to throw away or sell a perfectly good wheel to install one, and the additional weight permanently installed on the bike. Only the lightest (e.g. expensive) hub dynamos are comparable in weight to a bottle system. A DH-3N30 weights >850g for example (see )

    Once these hurdles are overcome, I think hubs are so much better in the long run.

    I’ve switched to hub dynamos and found them to be highly reliable, pretty much fit and forget. I am currently using a Shimano DH-3N30, a SON Deluxe, and a Shimano DH-T785.

    1. I actually bought the new SP 8D hub dynamo and took it and my existing front wheel to the LBS. For $50, they re-laced the wheel with new spokes. I don’t understand your comment about having to throw away or buy a wheel. Just rebuild it! Then you still have the same wheels front and back. As far as weight goes.…REALLY? The sandwich I just ate weighs more. Plus my old hub weighed 140g and the new dynamo hub weighs 396g. That’s a difference of roughly 8–10 oz. insignificant in the greater scheme of what kind of weight we carry with us on a bike.

      1. I don’t want my bike or luggage to weigh any more than is necessary, and I really don’t want the weight to increase at all beyond what is now, so any replacement equipment must be the same or lighter (I tour in the mountains, and on my last tour I did 30,000m climbing in a 2 week 1200km trip).

        I’ve been quoted >£50 for re-lacing — almost the price of a new wheel — and I don’t think it is worthwhile on a part worn rim, so if I buy a new rim I’ve just bought all the parts for a new wheel, therefore no parts needed from the old wheel. Your mileage may vary.

  13. TOM RENNIE avatar

    Believe it or not, this cheapo from Ebay (under £20.00) actually works fine!
    I ditched the fiddly phone holder & used rubber bands plus a safety strap for the smartphone and taped the electronics box to the stem. The bottle dynamo can be fitted/removed to the front fork very easily if you only need the facility rarely.

  14. great article,lots of info for a oldie but newbie rider,what bike was it fitted to

  15. Hi Tom,
    great to see this thoroughly tested,
    I cant afford a new hub and wheel rebuild, so pls can you confirm that it will work with a 6v/3w bottle dynamo to charge my smart phone?
    I realise it’s less efficient but I go through wheels like guitar strings so i’d be happy with a bottle dyn
    thanks in advance,

    1. I’ve successfully used it with a bottle dynamo, though the current wasn’t enough to keep my battery-hungry smartphone fully charged all day using 3G+GPS.

      1. thanks for the quick response mate,
        i’d have 3g off but might use gps on my Lumia 520, do you think it will be successful;?

        1. I couldn’t tell you, sorry! I imagine you’ll keep it running for a few days at least, after which you might need to top it up with a full charge. Airplane mode helps prolong battery life…

          1. thanks dude, worth a try I think!
            thanks again for an informative review on something that seems relatively untested so far.
            best wishes

  16. Hey Tom,
    Great article, I too have purchased a Tern P24h and the Reecharge system for touring in Europe. One question that I had after reading Biologic’s FAQs was about the system overloading when traveling over a certain speed. They say it will overload on a 20″ wheeled bike when going over 25km/h but what they don’t say it whether the unit will automatically shut off to protect itself and turn back on when the speed is reduced. Did you experience this issue during your testing?

    1. Hi Rob — I’ve never had this problem in practice. I don’t think you’ll go much more than 25km/h unless you’re going downhill! It’s easy enough to disconnect the power pack, I suppose, if you’re worried about overloading it. I agree it would be useful to have some real world testing done on this; nobody wants to fry their electronics!

  17. Thanks for this Tom — I’ve been dithering over dynamo hubs and chargers for a while so this (well-written) article couldn’t have come at a better time. As nice as it is to simplify things and reduce the need technology, I think things like this also provide more independence and the option to head literally “off the grid” a bit more. I had looked at the sunup system as a simple option, but unless I’m wrong it won’t work with disc-equipped bikes?

    1. No, the SunUp won’t work with discs. I’m also not a fan of the power pack that comes with it.

      As with all technology it depends on the context and the end towards which it is used. There’s a time for going low-tech, and likewise a time for judicious use of technology to enhance an experience.

  18. Hi. Just wondering, the grey unit is just a bigger battery isn’t it? There’s plenty batteries on the market you can use. The charger itself is about 25 quid online… I’m thinking of it as I have already 5V usb battery and charger itself comming with microusb plug…

    1. The grey unit is the core of the system. It consists of the battery, charger, cable interfaces, switches etc.

    2. Yes, you’re absolutely right. I’m using the Dynamo Kit alone with a regular Power Bank with a Micro USB input and it is working perfectly well. You can charge any device which supports a regular USB charging cable. As long as you don’t need the different adaptor plugs or the silicon strap thing and don’t mind figuring out a mounting solution for your regular Power Bank it is a lot cheaper solution.

  19. Yes, excellent and interesting article but God save us from putting all this stuff on a bike. I ride mine for the utter joy of getting away from electronics and computers!!!!

    1. Which of course is entirely your decision to make. Other people may well be interested in taking electronics with them!

  20. Excellent article — exactly what I’ve been looking for but didn’t answer all my questions. I have a tern link p24h ( purchase wholly inspired by you article on it:). ) — i was wondering if you could still use the valo light at the same time as charge a device? Second question — how does it connect to the dynamo — is it fairly easy/obvious? A picture would be great 😉

    1. I’ve been using the light and charging the power pack at the same time. It works, though the current and thus charging efficiency is reduced. The connector is a fairly standard one like this, which should be supplied with your hub. It’s just two wires; nothing complicated!

Something to add?