120w solar panels possible and feasible for my ebike?
Posted by catboy519@reddit | ebikes | View on Reddit | 23 comments
Contextual points: * I live in the Netherlands, a flad country but there are always winds * I bought my ebike at a bikeshop * my fastest charger is 3 ampere, 36 volt ebike
Question 1: my bike manual says "charge battery when it is not in use". Does that mean simultaneous using and charging will damage or blow up stuff? I know that not every manufacturer advice necessarily has to be taken strictly.
- If charging while using isn't an option, I have an alternative: use battery 1 while charging battery 2 and then swap batteryes when full n empty
Question 2: can solar panel be converted to 230 volt? If not, then how do I get it to work with my charger designed for 230 volt?
Question 3: if volts arent a problem but the panel generates, lets say only 1 ampere of current while my charger is meant to charge at a rate of 3 ampere, what would likely happen? Would it just charge slowly or would the charger refuse to work? Or the bms refuse to accept the lower current? Anyway if this is a problem I could still "downgrade" to my 2 ampere charger.
Idea, with possible flaws? * I modify my rear rack so that it can hold both 2 batteries and the solar panels and the chargers and everything else needed * if the temperature outside is outside of the 10 to 30 degree range, charging might be problematic * if its cloudy, can I still get 100 watts minimum? * if its raining, how do I protect all the electronics?
So question 4: is this idea feasible?
My goal is to sometimes make a long road trip at a reasonable speed without getting tired or sweaty or having to a carry lots of food and water so most the power has to be electric.
I know there are people who ebike with solar power but is it feasible for ME?
Ohm_Slaw_@reddit
You'd have to learn an awful lot about electricity and electronics. (Which can be fun.) Grin Technologies have done a lot with solar powered bicycles, I would look at their builds.
Solar power will be difficult. It's hard to get enough surface area to make a difference. Solar panels are large, flat sail-like objects that catch a lot of wind. Grin put solar panels over a streamlined outer skin, which stabilized the panels and reduces the wind resistance of the bike. Pretty cool.
catboy519@reddit (OP)
Heres what I know: * dc and ac * watts volts ampere * charger does cccv * battery has 3 pins so I guess it communicates with charger (oem)
What do I need to learn?
Ohm_Slaw_@reddit
Start with basic energy usage. Put one of those DC amp meters like they use for RC cars between the battery and the controller. Get a good understanding of what your energy consumption is and how many peak amps you need to generate.
Get a solar panel and see what it outputs. Does it actually generate enough power to matter? How much time in the sun do you need to replace what you use on a daily basis?
The first question you have to answer is, is it worth the trouble?
Biff1@reddit
You can learn a lot from the bikes in "the sun trip" competition where people go from Europe to China with solar bikes. https://youtube.com/@thesuntrip?si=Rs8PcC35RDwHGYLW
Ok_Weird_500@reddit
It's technically possible. It isn't practical.
I watched this video recently. But there seem to be others who have also done similar to what you seem to be asking.
https://www.youtube.com/watch?v=0Y4qlkciOcs
Personally, I don't think the solar charging is practical. Just take extra batteries, and swap them over as needed. And if it is a multi day trip, charge them overnight wherever you are staying.
catboy519@reddit (OP)
2 batteries will only get me so far. Would be nice to charge 1 of them while riding.
I want to make a long roadtrup within 1 day. Charging is just too slow to make stops for it.
Nibb31@reddit
A 700Wh battery can get you 100 km on eco mode, which is 4 hours of pedalling.
2 batteries is 200 km and 8 hours pedalling. Have you ever tried riding for 8 hours ? How much do you expect to be doing on your long trip.
catboy519@reddit (OP)
When there is strong headwind, my battery only lasts 80 minutes at 25 km/h (or an even lower speed) giving me a range of about 30km per battery if there is headwind.
I could slow down and get more range, but slowing down is exactly what I want to avoid on long rides. I would not want an 8 hour ride to turn into 12 hours.
Im not exactly sure how much power input my charger would need but I assume it peaks at 42v3a=126watts, then account for energy loss so maybe around 150 watt input.
Nibb31@reddit
You are not going to be able to charge a battery, nor are you going to get 100W, out of a solar panel that fits on a bike rack. To get 100W, you are going to need nice sunlight and at least 200W of solar panels.
You are also going to need a DC to DC solar charger and if you battery is a good brand, some sort of circuitry to trick into believing it's connected to a brand smart charger.
There are folks who do this for long distance trips, but they use trailer covered with solar panels.
LargeNerdKid@reddit
1: No
2: Yes
3: Slowly
4: Yes
reddit455@reddit
feasible for you? yes.
how much equipment do you wish to carry?
what are the panels mounted on? you'll need a trailer as well as WEATHERPROOF electronics to let you charge the battery and power the motor at the same time.
How we built an e-bike with unlimited range
https://www.youtube.com/watch?v=Wh33yQMl1E4
what you are asking is not mysterious.. you just need to be specific then find the equipment that matches your needs/expectations.
eBikeHelper@reddit
Not trying to be rude but question 2 highly implies you don't know basic electronics. Specifically the difference between AC and DC.
Setting up a custom solar charging system safely requires in-depth knowledge and good experience. So I highly recommend you study a lot more before buying or trying anything.
Solar panels of these sizes put out around 12-40v DC. But never constant voltage since the sun exposure is never constant. They just have an ideal max.
Your 36v ebike pack is multiple li-ion batteries. To charge it needs 42.0v. Your charger takes 120 or 230v AC and converts that to 42.0v DC*. Many who setup solar chargers convert the low DC voltage output of the solar to 120v AC, plug in their normal 120v AC to 42.0v DC charger, and charge their pack.
The newer solution is to find a boost charger that takes the variable DC solar panel output, regulate and boost that to 36v or 48v DC.
Like this Renogy boost solar charge controller
But again, the setup and use of any of that is not something to blindly play with.
catboy519@reddit (OP)
Define basic knowledge. I know the difference between DC/AC but it is not something I thought about when writing tbis post
Okay that abswers my question2. For me it would need to be 230 volt.
My battery has 3 pins on the charging port so I guess the bms communicates with the charger. My bike is OEM stuff bought in the local bike shop. I dont know if using anither 36v charger would work or even be safe.
Remaining Question: 1, 3, 4?
eBikeHelper@reddit
I directly answered 4. 3 is what I'd define as basic electrical knowledge. Calculating watts... I also gave you a direct link to what takes care of that.
1 and your third pin topic is a different rabbit hole. If your bike is a bosch system, you're stuck.
I'll repeat. You need to do more studying. If you want someone to walk you through everything in a low level detail or just do 100% of the work of building your desired setup, expect to pay. There are endless "electronics 101" classes on YT. If you want to do it on your own, I'd start there.
catboy519@reddit (OP)
I directly answered 4. 3 is what I'd define as basic electrical knowledge. Calculating watts... I also gave you a direct link to what takes care of that.
3 isnot a question about electricity, its a question about how the bms abd charger respond to low current. The charger could receive 230v, but will it accept the current if its lower than what the charger wants? For lets say 115w the charger needs 0.5 ampere but what if the charger only receivers 230v at 0.2 ampere?
My bike is not bosch. But I think the charger and bms are specificslly designed for eachother
I know hoe voltage/ampere/watts/dc/ac works so my question isn't about that. Its more about how to install the solar panels and about the bms and charger.
eBikeHelper@reddit
No offense, but this is the max spoon feeding I'll do for free.
It is about watts. If a charger is trying to push X watts and it's power source can't produce more than that, since some is lost in conversion, something will fail.
I still gave you a direct link to a solution but you seem to want to ignore that.
Best of luck to you!
Agitated-Country-970@reddit
You're experiencing catboy519's documented pattern:
He asks questions but won't do basic research himself:
Pattern across multiple communities:
What you're seeing:
The issue: He wants you to do all the thinking and research for him rather than putting in effort to learn. This is learned helplessness, not genuine inability.
You're right to stop the spoon-feeding. He has the capacity to research (writes detailed posts, participates across multiple subreddits) but expects others to do trivial tasks for him.
Your frustration is valid and shared by many who've tried to help him.
band-of-horses@reddit
The easiest way to charge your bike with solar is to purchase a battery power station (jackery, ecoflow, bluetti, anker, etc) and hook a solar panel up to it and then plug your bike in. Not the cheapest way, but the eassiest.
geekroick@reddit
Look at the amount of surface area that's required in this video to get circa 60w from two panels wired together for a theoretical maximum 100w. And it was filmed in the bright Florida sunshine.
https://youtu.be/bT9wXLHoI3A
The easiest way to do what you want is to use the same MPPT step up controller as seen in the video, that way you don't need to involve AC power (and its unnecessary power and heat loss that also lowers your charging speed) at all, you recharge with a direct DC current stepped up to 42v. Panels should be waterproof, put the MPPT controller in a waterproof bag, use waterproof locking connectors, you should be good.
At best (in the most ideal circumstances) you'll get about 80 percent efficiency from a panel, so '100w' is more like 80w. If you want more than this you're going to have to get additional surface area, so more/bigger panels. Unfortunately there is no guarantee that you'll get enough power on cloudy days unless you have even more additional panels.
And of course you'll need plenty of charging time.
catboy519@reddit (OP)
I don't know if that would work. My bike is all OEM so the bms might expect a specific handshake from a charger am I right? The manual says to only use the charger that came wuth the bike.
geekroick@reddit
It depends on what kind of wiring/plug is used on the charger. Most chargers are simple DC, positive and negative wires. If you are stuck with using the supplied charger you'll need an inverter (DC 24v to AC 240v).
catboy519@reddit (OP)
I just wonder what the third pin us for
Adventurous-Quote190@reddit
Re: question 4
Yes, it is feasible, but not for most people.
I actually met two people that were on a cross country bike tour across the US using solar powered bikes. This was not using off the shelf easily accessible consumer products; everything was custom built for this. The riders were engineering students, and this was all part of some project working on their PHDs. They were pulling a trailer behind them with their bike touring gear, and the trailer was covered in solar panels. They stopped by the bike shop and let us check out their setup and ask questions. It was a pretty fun day!