SON Ladelux Review

My SON Ladelux Review

“If you keep carrying old bricks, you’ll keep building the same house.”

Germany and Regulations

The SON Ladelux review must start with some context. You have to understand that Germany has bazillion regulations for literally *everything* and that includes bicycle (dynamo) lighting. The infamous 6V/3W number/value a dynamo is actually still today in 2026 and it is based on halogen bulbs. I have a detailed video on the subject , though suffice to say with LEDs we have gone light years (pun intended) ahead of halogen bulbs, yet the German standard still requires StVZO lights (having K-mark) to respect that.

So while LEDs are 30x (yes thirty times) more efficient, LED bicycle lights and dynamos are still stuck in century old technology. This is the most important part for you to get out of this SON Ladelux Review.

While a lot of people when they think StVZO lights, they think cutoff beam, a light has to meet ***multiple*** standards (we are talking Germany after all…) so yes cutoff/light distribution is one, however ELECTRICAL specification is another.

Which means the Ladelux being German it means the Main beam/cutoff beam needs to produce 2.4W in order to meet specification. It says it right on the light itself.

LEDs are very bright so you don’t always need 2.4W (actually for most riding ~0.7-1W is plenty with GOOD optics). To do that you need variable intensity/dimming that is USER selectable (as on all of my products). The SON Ladelux (or no other dynamo light actually) does not seem to have variable intensity (well it does with varying speed but this is not dimming/regulated light output, it is a ‘feature’ of dynamos). At 15kph it is 2.4W, you can’t manually change it to 1W/50% across all speeds for example. It actually is probably even more than 2.4W at above 15kph. Therefore you CANNOT select how to distribute the (limited) available power. So most dynamo lights flicker at low speed and leave little or no power to do other things (such as High Beam, or USB-C charging). Dynamos especially below 15kph barely go above 3W (due to the above said ancient German regulation….) even with ALL the tricks in the book (more on that below) so if you want the lights on and have some lights to spare you are out of luck or you need a buffer.

Internal Buffer or Largely NOT for SON Ladelux

So (similar to my own products) I discovered very early in my electronics journey that for charging (and no flicker at low speeds) you need a buffer battery – dynamo power outputs way to variable to be useful. Several things you need to know about the SON Ladelux buffer battery.

Most importantly it has to do a LOT of jobs and as you can imagine multitasking means things get not done – just like people.

1. Capacity of the SON Ladelux is 1200mAh, as compared to 1600mAh for my products (and others on the market such as the Exposure Revo 5) and it not being used to full capacity (it works only in the 20-80% charge) you are dealing roughly with a 720mAh capacity or LESS THAN HALF of a 1600mAh cell, ***before any conversion losses to 5V, etc.***
2. Most (if not all) supplementary functions (besides the main/cutoff beam) – High beam as well as charging depends on the battery. So if you want lights and charge you better be riding faster than 25kph. Just charging, if you are riding below 15kph you will tap into the buffer quite a bit and eventually run out so you will lose charging (and high beam).
3. There is no real ‘pass through’ as in all my devices (starting from The Stalker) so even if you have enough power from the dynamo, if the battery is not within the 20-80% you are out of luck – no charging and no high beam. Why is that an issue? Li-ion battery recharging takes TIME. You can’t just pump in all the current you want, nothing beats ”pass through in efficiency and the SON Ladelux does NOT have that.
4. THE SON LADELUX BATTERY IS NOT USER REPLACEABLE AT ALL. (Garmin Varia Vue 820 is the perfect example of what is currently possible for a bike light).
5. Last but not least, there seems to be no battery management system (the stuff that prevents batteries from catching fire for example) – li-ion cells need very tight charge management when charged above 80% (that is why all quoted times for electric cars and such is to reach 80%), and there are plethora of very good solutions for that. The SON Ladelux does NOT have any kind of management they simply seem to have chosen to not deal with the critical states (<20% and above 80%). The claim is that charging below 80% prolongs battery life and what SON also quote themselves. Fair enough. That is partially true, though battery management solutions (as on smartphones) do that ***as an option***, they still charge to 100% occasionally. As mentioned above not having the ‘complexity’ of battery management makes you potentially lose ~50% capacity. We are dealing with small power cells (~4Wh) and a largely mature technology so the cell will most likely be ok, though such an omission of battery management is a head scratcher.

Innovative?

What you need to know is that dynamos are what they are because of GERMAN regulations (VIDEO). This is the ONLY regulation in the world and as I already mentioned they are severely handicapped as this is based on having a light and a halogen bulb.

Unfortunately. this has de facto become the international regulation Even though if you are not in Germany it doesn’t matter even 1 bit…. When that regulation came about, charging things while cycling wasn’t a thing. GPS, cellphones didn’t even exist, we used vacuum tubes to listen to the radio and watch TV!

You have to understand that with parts they had on the shelf, without any NEW development me and SON made a dynamo 300%, yes 3 times more powerful that what is currently out there, 50% more efficient with 3W at 5kph (walking pace!). The technology is there.

So rather than making a better dynamo or update things you have to resort to

ALL The Tricks in the Book.

First of all even with all I am going to describe, below 15kph you are still in the 3W range which is largely not enough (most high power devices need at least 5W to be charge ok). This is largely a physical limitation of the coils, magnets etc which are all done to meet the ancient German regulation. You physically can’t get more out. So you have to resort to trickery – or know as Maximum Power Point Tracking (MPPT).

Another German product (Forumslader) has done, it though in a kit form with wires sticking out and Igaro made it in a light actually, though you need an app to get the most out of it…. Which means you squeeze EVERY possible milliwatt from the dynamo at every condition. The principle is not new (paper here) and has been done THEORETICALLY.

You can do it either actively over all speeds or passively (like I have done with my products over the speed were most people ride).You need a FAST microcontroller and LOTS of code. Again Stealth was a paper (on the mathematics of propagation of waves) by a soviet scientist until Lockheed Martin actually made a stealth plane. Making theory into practice takes a LOT of headaches, though while nice you are still trying to squeeze out something that was not really there. Kudos for SON if they actually managed to do it, though seeing that the SON Ladelux is forbidden to operate on e-bikes (12V DC) and is dynamo only, means for at least some part they rely on passive MPPT (this makes things AC/dynamo only). There are multiple ways to go at it so SON (and anybody) can get creative, though one thing that we don’t need to be creative is USB-C as the work has already been done, yet SON Ladelux chose to.

USB-C Standard NOT Respected

It is nice to have standards and yet the SON Ladelux does NOT follow them. The USB-C specification has 3 current levels Default (2.5/4.5W), Medium (7.5W) and High (15W).

From experience Medium is well a good medium ground for high power devices like smartphones (Garmin Edge x40 and Varia 820 charge at either Default or Medium depending on the charger), HOWEVER, ‘3W dynamos’ at most riding speeds are not that, so picking the lower (Default) value is practical, especially if you want to use lights and charge. Ladelux claims 5W (5V/1A) steady output. There is no 5W ANYWHERE in the USB-C specification. Strike 1.

The SON Ladelux use a proprietary connector/button which is VERY nice (yes I am jealous). However, it only has 2 pins (+ and – . 10-20 years ago 5V is all you needed to recharge via USB. Nowadays the USB-C cable has 4 **additional** pins that ALL they do is *talk* with the other USB-C (compliant) device to discuss how they will charge. The 5V is not turned on UNTIL AFTER CABLE PLUG-IN AND HANDSHAKE. The SON Ladelux USB-C cable is always on. So (I know from personal experience here) some USB-C devices will interpret this a non-compliance and refuse to charge. Strike 2.

Lastly (I am doing some educated guesswork as I tried to do what SON have most likely done) if you announce Medium current (1.5A/7.5W) and limit it to 5W, some devices will also interpret that as an error (crap/bad charger). For example iPhone 16 Pro Max. In addition some Garmin Edge devices lose touchscreen functionality when being charged from the SON Ladelux. Also some powerbanks (notably with USB-C bi-directional ports) will also not charge (as there the USB-C specification is paramount to be respected). Strike 3.

12W power??!?!

So why is it so limited in when they claim lots of power available – 12W it is right there in their website:

First of all this is quoted at 40-kph per hour or 25mph. Let me repeat this is at 40kph/25mph. To achieve this speed SUSTAINABLY, you need to look something like this.

You have to put out 350+W and in general experience quite a bit of pain. People who use dynamos almost NEVER (or actually never…) go those speeds unless on some descents, where you need to climb for hours at 10-12kph to get to them….

Second, I have personally asked the SON engineers who designed the Ladelux (during Eurobike 2024) about that number, so has the Igaro engineer allegedly and i did not get a comprehensive answer then. The internet currently does not like facts so any kind of bold claim goes… I give SON the benefit of the doubt that English is not their first language and I do not speak German, though no answer.

Though Physics is physics and Igaro have allegedly measured the SON28 dynamo hub and can get about ~9.6W, this is a limit of the coils/magnets, etc. Give it some tolerance and call it 10W. Maybe this is why Ladelux has 10W on the housing…

INefficiency

According to the SON engineer in a thread on Reddit, the SON Ladelux circuit in operation consumes 0.2W (200mW) or already 6% of the nominal dynamo power of 3W. No charging, no lights, just being active. This is VERY inefficient in today’s terms, where typical operation currents are MICROwatts (1000x less)!!!

Second, on order to avoid over voltage (frying the electronics) in some conditions, the SON Ladelux presents a constant load the dynamo which causes resistance. While 3W lights do slow you down about ~3min each hour you are riding with the lights on (I actually measured it) the SON Ladelux creates mechanical resistance even when it is not actively performing a task. From an engineering standpoint, creating drag while the internal battery is full is an inefficient design choice.

The SON Ladelux Review Conclusion

The SON Ladelux makes some bold claims for currently (JUL2026) the most expensive (by a 10-20% margin) dynamo light+USB-(C?) charger package.

Dynamos are as ‘bad’ due to the German (or de facto the international) regulation based on 100+ year old technology – halogen bulbs. SON being a German company that manufactures dynamos, is in the unique position to actually change that by either making a dynamo with better power output, especially at lower speeds below 15kph/10mph or contact the regulators and influence change in the regulation directly. They choose neither and as such the SON Ladelux is a missed opportunity and built around a fundamentally outdated concept.

While the electronics might do the best of what a ‘3W dynamo’ can provide, the 10-12W output numbers get pushed into all kind of advertising material and get taken at face value by consumers. While no publicly available independent tests exist to confirm or disprove those numbers, they are only possible at 30-40+kph/18-25+mph which are speeds that are not sustainable in the context of cyclist that will use dynamos – notably commuting, touring and ultra distance riding. Therefore those numbers even if possible are not practical or readily achievable in real world riding, they do look good on advertising materials though. Couple that with some of the engineering choices that come at cost of efficiency on an already power limited dynamo, the choices are not so easy to understand from my point of view.

Way back in 2022, SON were openly denying ever making a dynamo powered charger, the SON Ladelux was announced as a brochure only in August 2023 during the Paris-Brest-Paris 2023 event, this is where I met Wilfried Schmidt personally. The Ladelux was widely anticipated, and it took years until physical products were available outside of prototypes in bike shows. From a dynamo manufacturing company only (The Edelux seems to be almost exclusively a Busch and Muller electronics in a nicer housing, the SON rear light is a 1:1 copy) they have hired electronics engineers and spent years developing a product based on the above mentioned old regulations. Therefore, I do not think SON with their products will try to change the dynamo market, as a company they have too much invested in both time and resources and taking a new engineering path is a decision that few companies have ever pulled off.

Compromise is part of any product design, so this is ok, I know that. These are my 2 cents. I am speaking of somebody who started way back in 2019 from 0 and had to learn it all the really HARD way, not knowing what is a resistor was, to actually making some of the innovative dynamo powered products on the market. As an independent developer without a massive marketing network, this blog is my primary platform to share data-driven engineering perspectives directly with the cycling community.

Thanks for reading!

NB: Original text is in English. All other languages are automatically translated so I take no responsibility of correctness.

Source: Personal conversations with SON engineers, Reddit, SON Ladelux Manual and most importantly my own headaches and experience designing dynamo lights with a charger.