Twin Heads SRL Lightcharge  £41.00


Simple, inexpensive USB charger for your dynamo-equipped bike

Weight 62g   Contact

by Dave Atkinson   August 28, 2014  

The Lightcharge USB port is an inexpensive option for adding a charger for your devices to your bike if you run a dynamo of any kind. It works pretty well and has stood up to some weather too.

There are options for hub or bottle dynamos (and now a range of colours) but I tested the standard black unit, running it from a SP-PV8 hub dynamo. Fitting it is easy: simply wire in the Lightcharge with your existing light circuit, and the buttons on the front of the head unit allow you to choose between lighting and charging; you can't do both.

The wire from the hub to the unit ends in a micro-USB plug, so it can't be shortened. I found it over-long, so I zip-tied up a few coils to take up the slack. I initially thought the bar mounting mechanism, a simple elastic bungee, was a bit cheap but to its credit it's worked perfectly well. You could replace it with zipties if you wanted a permanent attachment; the Lightcharge is designed so it can be easily removed, although it's not the type of thing that's especially likely to get stolen.

It's simple to use: switch to charge mode, connect your phone/gps/etc via a standard USB port and ride off. Once you've got enough speed up your device will start charging. I used it mostly with an Xperia Z1 compact phone which is a little bit finnicky about what it'll charge from, but it was fine. I found that the 250mA charge wasn't quick, but it was enough to slowly increase the level of charge even when I was recording a track on the phone using Strava, and flicking the screen on from time to time. So in theory you should be self sufficient on longer rides, providing you don't have more than one device to do. Given that many larger devices charge at 1A, you'd be waiting a while to fill up an iPad or similar.

You can't charge stuff up at night, as you need the power to your lights and it's an either/or solution. And I'd be reluctant to use it in the pouring rain as there's no obvious sealing in the USB output. I've ridden with it on the bars with the input cable attached and the USB port cover sealed, and it's been fine in spite of some pretty filthy conditions. If you only needed one specific lead attached, you could glue the lead in with some epoxy resin, or seal it with Sugru. Then it'll probably be fine in all conditions.

The Lightcharge is one of the cheaper options for getting a charge port on your bike. It's not as elegant or quite as effective as something like the Tout Terrain Plug, and it does take up some space on the bars, but it does the job it needs to pretty well and it's simple to fit and use.


Simple, inexpensive USB charger for your dynamo-equipped bike test report

Make and model: Twin Heads SRL Lightcharge

Size tested: Black

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Connect it to the dynamo of your bicycle, hang it to the bar and pushing a button, you can decide if you need the recharge mode or the light mode

Phones, smartphones, iPods ® and MP3 readers:' plug them to the USB, and you can recharge while riding!

lightcharge does not waste the energy: the electronic devices can be uploaded at a low speed with no effort.

People who does not have much physical strength can enjoy the lightcharge technology.

Connected to a common dynamo and starting from 13 Km/h, lightcharge can produce enough energy allows to charge most electronic devices.

To reduce the normal braking effect of dynamos, lightcharge can be connected to a rubber insert that enhances the head of the dynamo from 20 to 28 millimeters.

Now you can have a pleasant riding and your devices always uploaded!

Tell us some more about the technical aspects of the product?

Size: 45 x 43 x 31 mm

Weight: 23 gram

Input (A.C. or D.C.) from 3.5 to 18V and output direct current (D.C.): 5V and 250mA constant

Speed required for maximum production: 13 km/h

Rate the product for quality of construction:

Generally good. Lead a bit long, ports not well sealed when in use.

Rate the product for performance:

Fairly low charge level but enough to keep you topped up.

Rate the product for durability:

Not overbuilt but should be fine, it's not in a vulnerable position and you can remove it if you want.

Rate the product for weight, if applicable:

Nice and light.

Rate the product for value:

Good value, other options can be a lot dearer.

Tell us how the product performed overall when used for its designed purpose

It did the job, charge isn't fast but it's just about fast enough.

Tell us what you particularly liked about the product

Easy to fit.

Tell us what you particularly disliked about the product

Not especially well sealed.

Did you enjoy using the product? Yes.

Would you consider buying the product? Yes.

Would you recommend the product to a friend? Yes.

Overall rating: 7/10

About the tester

Age: 41  Height: 190cm  Weight: 102kg

I usually ride: whatever I'm testing...  My best bike is: Genesis Equilibrium 853

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Experienced

I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding, fixed/singlespeed, mtb, Mountain Bike Bog Snorkelling, track


13 user comments

Oldest firstNewest firstBest rated

Why bother when you can buy, for about the same price as you would pay for an average front light and this, an Axa Luxx Plus light? Axa you get 70 lux of light output too!

blog rowerowy - my blog about bicycles (written in Polish, but feel free to visit me! Smile )

mikroos's picture

posted by mikroos [254 posts]
28th August 2014 - 17:09


mikroos wrote:
Why bother when you can buy, for about the same price as you would pay for an average front light and this, an Axa Luxx Plus light?

I can't speak for the reviewer, but I'm potentially interested in something like this rather than the Axa because I already have a front light, and the Axa bracket looks awkward to mount on a caliper brake:

posted by armb [69 posts]
28th August 2014 - 18:35


plenty of people want a charging solution to add to an existing light setup. I run a supernova E3 Pro and i don't really fancy swapping that out Wink

Dave Atkinson's picture

posted by Dave Atkinson [7855 posts]
28th August 2014 - 18:47


For those who want to make their own for around a tenner -
DIY solution.

posted by Dr_Lex [215 posts]
28th August 2014 - 21:59


Looks good. I have a Kemo M172 charger, which is around a tenner cheaper, but the wide flat body makes it nigh-on impossible to mount neatly on a bike. It's also fine with charging older "dumb" devices like our Satmap Active 10, but smartphone charging tends to cut out above a certain speed. So I can see one of these in my near future.

posted by Mr Agreeable [162 posts]
28th August 2014 - 22:50


armb wrote:
the Axa bracket looks awkward to mount on a caliper brake:

It looks like that because it's mounted the wrong way.

It would be much easier to install it with a bracket that goes below the brake arms. It wouldn't collide with the tyre as the brake is located above the edge of the fork's crown and the mount would look much cleaner.

It really doesn't have to look like this. Cheers.

blog rowerowy - my blog about bicycles (written in Polish, but feel free to visit me! Smile )

mikroos's picture

posted by mikroos [254 posts]
29th August 2014 - 7:39


Actually on my bike it really would have to look like that too. My mudguard barely fits between the brake and tyre, a bracket strong enough to take a light cantilevered out like that in there as well wouldn't work.

posted by armb [69 posts]
29th August 2014 - 9:20


Dr_Lex wrote:
For those who want to make their own for around a tenner -
DIY solution.


1999 called, they want their web design back. (It claims to support Firefox and Chrome. I'm using Chrome.)

posted by armb [69 posts]
29th August 2014 - 9:24


They're on offer for £30 at Roswheel right now, including free shipping. Button pressed.

posted by Mr Agreeable [162 posts]
29th August 2014 - 14:57

1 Like

I've had one of these for a while now. Unfortunately I haven't had time to do some proper testing but I give you my anecdotes.

I'm using it with a Shimano DH-3N80 hub dynamo.

I have left it on my bike permanently so that includes in rain and snow. Seems to have been unaffected.

Mine came with strange connectors. I forget what now but I had to chop them off and wire my own.

The switch in mine is in backwards - such that I choose lights to turn on USB power and battery to send power to the lights. I now have it mounted under the top tube so I can't see the label anyway.

If I try to power my iPhone 4 from it the iPhone pops up a dialog suggesting the device doesn't provide enough power to charge. That makes sense when you are just starting off but alas once you are up to speed the phone doesn't start charging. I seem to have to accelerate very quickly from being stopped in order to make the phone happy - and it is all ruined when I catch a red light.

I recently went on a 2 week tour. I powered my GPS from an external battery which I in turn charged from the dynamo. The battery went down every day so I don't know how much, if any, charging was taking place. Because of where it was all mounted I couldn't look whilst cycling so I don't know what was going on here. Luckily I had big batteries and found power points every few days so it wasn't an urgent issue during the tour.

It was quite cheap though.

I want to measure the output at various speeds and see how stable the power is as well as get some sense of efficiency but currently lack the time, and some of the equipment.

posted by cqexbesd [44 posts]
2nd September 2014 - 17:29

0 Likes says it's 250mA output. claims 500mA, or 800mA if your dynamo is up to it (hub dynamos generally saturate at 0.5A, but can output higher voltages at that current; it's not clear if the M172N will make use of that or not).
The LightCharge is neater, but the Kemo looks like a better option for at least some uses.

( (about M172, not M172N) isn't very encouraging though. Anyone have experience with the M172N?)

posted by armb [69 posts]
8th September 2014 - 11:38


It would be much easier to install it with a bracket that goes below the brake arms

I now have an Axa Luxx70 Plus, bought for a bike with V-brakes, but I did try it with my calliper brake bike. A bracket below the brake really wouldn't work, but I could probably make a fairly neat above brake bracket mount with a 3-D printer (replacing the end of the standard one in a similar way to the suspension fork versions it comes with). But that's not a much easier installation.

However, the Cyo Premium on the road bike lights up at much lower speed. I haven't compared them on the road yet.

posted by armb [69 posts]
19th November 2014 - 20:09


How do you mount the Sony Z1 Compact smartphone?

JumboJuice's picture

posted by JumboJuice [18 posts]
20th November 2014 - 4:11