People often wonder whether they should invest in a dynamo hub or a portable solar panel
for charging electronic devices while on the road.
This question usually pertains to cyclists on self-sufficient bike tours, as they may
not have access to power outlets for days, or even weeks.
And I want to give some insight into that today, with a few fun tests to compare the
performance of both methods.
This is far from a scientific experiment, but it’s the best I could do and I hope
it gives you some references or, at the very least, serves as entertainment.
Let’s start by talking about what wheel hubs are.
They are the components that exist at the center of your wheels.
More specifically, on your front wheel, you could have a conventional hub or a dynamo
hub.
Dynamo hubs have internal magnets and copper coil windings and they generate electricity
from the rotation of the wheel.
This means that whenever the bike is in motion, mechanical energy is being converted into
electrical energy.
This electricity can be used to power your lights, making it for a safer ride during
the night, and it could also be used to charge small electronic devices, such as your phone,
for example.
But is it worth it?
As I mentioned, later on we’ll compare it’s performance with that of a portable solar
panel, and I can assure you the results are interesting.
For this video, I needed to dig into some old footage I have from a test I did a year
ago.
At that time I still lived in Brazil and recorded all of my videos in Portuguese.
But that day, I went out with the specific purpose of riding my bike for an hour, at
a constant speed, and see how much of my phone battery would get charged after that one hour.
The dynamo hub is most effective for charging electronic devices when riding at around 16km/h.
Because the hub generates alternating current with variable voltage, I used a device from
Busch and Muller, called e-Werk.
It takes in the alternating current from the hub and converts to direct current at constant
voltage.
You can select the maximum current and the voltage you want the output to be.
After that initial set-up, it’s as simple as plugging your phone’s USB cable and riding
the bike.
I turned the bike lights off, to make sure all the power from the hub was being directed
to charging my phone, and I also turned the phone off to see how much it would be charged
without any power being consumed.
You can see that as I start moving the bike, the phone detects that it’s plugged in and
lets me know the current percentage of battery left.
In this case, I started the ride at 12%.
This is a very nice, flat lagoon with a perimeter of 18km.
Here I can keep a constant speed without stopping, so that the phone could charge without interruptions.
Ideally, we want to plug a battery pack to the e-Werk, and not the phone directly, since
going in and out of power can actually damage your phone in the long term.
After an hour ride, I checked the phone again for the updated battery level.
It was 28%.
So, doing the math, it took me an hour, or around 18km to charge my battery by 16%.
Roughly one percent per km.
To be honest, I expected a bit more, but there’s only so much we can do with a 3-Watt dynamo
hub without breaking the laws of physics.
A few days later I went off with a different purpose.
I wanted to see how my portable solar panel would behave in a similar situation.
Mine is a 15-Watt portable solar panel from RavPower, that probably doesn’t even exist
anymore.
I know, it’s 15W while the hub is only 3W, but this is the kind of solar panel people
use for bike touring and camping, so I still think it’s a relevant comparison.
Also, that maximum power can only be achieved with ideal conditions, such as direct sunlight
with a clear blue sky, and that’s definitely not the case here.
So I set up the solar panel on the grass, powered my phone off and plugged it in to
the solar panel.
I started the test at 9%, and left it there for an hour.
The main advantage of using a solar panel over a dynamo hub is that it doesn’t depend
on you riding the bike.
You can be charging your battery packs while having lunch, or even during the off days,
when you’re not riding your bike at all.
But that doesn’t mean anything if it doesn’t perform well.
So after that full hour I checked for the battery level on the phone, and it was 42%.
The weather was so bad that it actually started raining at the end of the test, but I was
impressed.
Even on a cloudy, overcast day, the portable solar panel was able to charge the phone by
33%, roughly twice as fast as the dynamo hub.
So should you get a dynamo hub or a solar panel?
It really depends.
A lot.
What do you need it for?
The dynamo hub is great for what it's been designed for, which is keeping your lights
on whenever you’re riding.
I like that, since I never have to charge my lights ever again.
But for bike touring, I would be more inclined to use a solar panel, especially if I go for
a long self-sufficient bike tour.
What about you?
Let me know in the comment section down below.
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like this.
Thank you for experimenting with me today, and see you on the next one.