How To Solar Charge Your Ebike

Posted on 04/15/2022 at 12:35 by Julian White

post #123 how to solar charge your ebike blog post title graphic

 

With fuel prices on the rise, many of us are turning to more cost-effective forms of transportation for our daily commute. 

 

The first option is an electric car, which is a great option. 

 

However, without a renewable source of electricity, we replace the price of fuel with a higher electricity bill to charge the electric car. 

 

The electric bicycle is another green option.

 

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In the image below, we see my electric fat bike. It’s like a mountain bike but has larger, wider wheels and a more robust frame. It also has an electric mid-drive motor and motion system called “pedal-assist.” 

 

ebike













Pedal-assist augments the rider's peddling by taking up the slack. It uses the bike's electric motor and battery to move you along. 

 

Using a pedal-assist electric bike for commuting means not using all your energy to move the bike forward. 

 

Pedal-assist helps us get to work without looking (or smelling) like we just rode the mountain stage of the Tour de France.


Commuting isn’t the only activity an electric bike can help with. 


white dog in front of a tent

My dog Snapper and I often head off on multi-day adventures, using my eFat bike for bicycle camping. 

 

We bring food, water, sleeping gear, and shelter. We also bring ham radio gear if we get into trouble. 

 

We can think of the electric bike as an extension of ourselves or even a lifeline. When the hills are too steep, or the road is too long, we can turn on the electric bicycle motor, making it easier to reach our destination, or keep it off and use it as a traditional bike. 

 

The extra get-up-and-go is there if needed!


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Carrying food and equipment for myself and Snapper, the load can become substantial. 

 

Usually, that load would be pushed along 100% using my leg muscles and caloric expenditure. 

 

This is okay until it’s not. 

 

Hitting the performance “brick wall” is when the electric mid-drive ebike motor can help. 

 

With pedal-assist enabled, my own 100% effort becomes 90%, 80% or even a maximum of 50% reduction of my effort. 

 

Some bikes even have a throttle mode, allowing the ebike motor to provide 100% of your forward motion, making carrying a heavier load more realistic on the path less traveled. 

 

It also makes it possible to extend the range if, for some reason, we need to race against an incoming storm or unexpectedly need to find a better-protected shelter. 

 

Naturally, the assistance only lasts until the battery dies, but there are no electric outlets during wild camping bicycle trips!

 

This is no longer a problem since we can now use solar power to recharge the ebike battery off-grid with our portable solar panels.


two khaki 60w foldable powerfilm solar panels and a genasun charge controller

To recharge an ebike battery, we need to bring our renewable energy source. 

 

My portable off-grid ebike battery charger combines a charge controller from Genasun and solar panels from PowerFilm Solar. 

 

The Power station is two 60W Foldable Solar Panels (F16-3600) made with amorphous silicon solar material making them lightweight and flexible. 

 

These panels pack small and don’t add a ton of weight, making them very easy to take along. 

 

The charge controller for my ebike battery (48V Lithium-Ion Hailong battery) is the Genasun Boost charge controller (GVB-8-WP-Boost) for the 54.2V (48v Lithium-Ion) battery pack. 

 

The controller is designed to take voltage from the solar panels, converting it to something the e-bike can use for charging. 

 

It also protects the battery from overcharging and finds the maximum power point (MPPT). 

 

My ebike is a GZR Raw.

 

The GZR uses a 48V Hailong battery to power a 250W Bafang M-Series (integrated Mid-drive) motor.

 

man holding charge controller

 

Wiring the Genasun charge controller for the Hailong 13S4P battery was straightforward. 

 

The same charging port is used for off-grid charging as the stock AC charger uses when charging on the grid from home. 

 

I added modular Anderson powerpole connectors to the charge controller and the ebikes battery charging cable. 

 

This makes plugging in and swapping out simple, whether from home or during an off-grid adventure.

 

Wiring up the controller


man holding charge controller cabling

The Genasun GVB-8 has four wires coming out of it. 

 

Two are for connecting the solar panel, while others link to the ebike battery. 

 

The wires are confusing, so please pay attention (see image above).

 

From right to left:

  • Yellow wire: Solar input + (Positive)
  • Black wire next to yellow: Solar - (Negative)
  • Next black to left of solar - Battery Negative
  • Next black wire on left: Battery Positive 

 

I find the Anderson Powerpole connectors perfect for connecting the charge controller and ebike battery. 

 

Whatever connectors you choose, be sure the individual wires don't touch each other during connector installation. 

 

Also, remove the battery and charge controller from any power source while making connections.

 

Charging

 

You will need a similar but unterminated version of your AC charging cable to charge the battery. 

 

Then, we will add the Anderson Powerpole cables to the unterminated DC charging cable on the unterminated end. 

 

For the Hailong 13S4P Lithium-Ion pack, the DC charging cable looks like this.

 

barrel connector to anderson powerpole cable


To charge the battery, I recommend removing it from the ebike. 

 

Place the battery on a dry surface away from sources of moisture and remove any other connections from the battery. 

 

Assuming you have already sourced an unterminated cable for your DC charging, plug your charging cable into the battery port of the charge controller. 

 

Do not plug the solar panel in just yet. Now connect the male end of your charging cable to the charging port of your ebike battery. 

 

You should see a green light illuminate the charge controller when the connection is made, then blink green every second while the battery remains connected to the charge controller. 

 

If it is as I describe, it is now safe to plug in the solar panel. 

 

If you get a red light illumination on the charge controller, the battery or charge controller has been plugged into the incorrect port, or the polarity of the connection is backwards. 

 

If you get no green or red light illumination on the charge controller, the fuse is probably blown. 

 

Remove the fuse cover on the battery lead of the charge controller, then inspect the fuse with a multimeter. 

 

If the fuse was blown, replace it with an identical fuse. Recheck your charge controller and battery connections and polarity before plugging anything into the charge controller or battery again. 

 

Finally, always connect your solar panel to the charge controller as the last step in charging. The solar panel should be removed first before the battery is disconnected from the charge controller when charging is complete.

 

Other battery types

If your battery is not configured in the same way as the Hailong battery (for example, the 3-pin Bosch ebike battery), your ebike battery can still be charged off-grid with solar panels. 

 

This video describes the connections required for charging Bosch e-bike batteries. 

 

About Julian White

Julian White, aka OH8STN, is a YouTuber, blogger and retired broadcast engineer. 

His blog and popular Youtube videos share education and adventures with the off-grid ham radio and emergency communications communities.


If you want to learn more about PowerFilm Solar or have a question for Julian, contact us!

 

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