One stop for solar charging ebike info?

General Discussion about electric bicycles.
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monster   100 kW

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Re: One stop for solar charging ebike info?

Post by monster » Apr 26 2020 9:12am

I used 100w panel on a shed to charge the bike.
It would charge in a day.
I think it could be worth the weight

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Re: One stop for solar charging ebike info?

Post by john61ct » Apr 26 2020 11:04am

The OP is talking about **portable** solar fr charging out in the countryside.

Everyone talking about stationary panels mounted at a fixed location, is missing the point.

And in any case, you want a good solar controller, no matter what, for efficiently charging the pack from a given panel wattage output.

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monster   100 kW

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Re: One stop for solar charging ebike info?

Post by monster » Apr 26 2020 5:40pm

Yes you could put a 100w panel over a bike.
You could charge you battery with a dc dc converter.
Expect to get 50w from a 100w panel tho.
Unless its direct mid day sun clear skys in summer.
50W is not nothing tho.
There is merit to it and if i were going on a round the world bike ride, i would take solar.
I have a kids trailer that would take a 100w panel easy.
For day to day use theres no point tho.

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monster   100 kW

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Re: One stop for solar charging ebike info?

Post by monster » Apr 26 2020 5:46pm

The problem with solar charge controllers is that they are not built for charging ebike batteries.
Therefore you need a seperate charger too which compounds the efficiency losses.
A dc-dc converter may not be as efficient but has less steps. So over all both methods will be similar efficiency.

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Re: One stop for solar charging ebike info?

Post by john61ct » Apr 26 2020 6:40pm

Well none of this is practical anyway.

But a proper MPPT putting out 48V is easy to find.

Going from there to whatever would be some loss yes, but far less than just using a dcdc alone I think.

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Re: One stop for solar charging ebike info?

Post by john61ct » Apr 26 2020 6:42pm


monster wrote:50W is not nothing tho.
Less than 1A worth of output, and for 4-5 hours at best

Pretty close to nothing


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monster   100 kW

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Re: One stop for solar charging ebike info?

Post by monster » Apr 28 2020 7:37am

48V is no good . the OP needs 59v to charge. Best to use dc-dc converter. Especially with the ghetto mppt as i explain

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ZeroEm   100 kW

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Re: One stop for solar charging ebike info?

Post by ZeroEm » Apr 28 2020 8:29am

Need to find that thread of the world traveler that went thru the same thing wanting to help power his bike thru the back country with solar.

I would like to do the same but with out a lot of high quality panels and the need for a roof and trailer with panels on them. I can make more watts by peddling down hills with regen on. E-bikes just require more power than solar can provide at this time, but keep trying. I want in too.
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Re: One stop for solar charging ebike info?

Post by Cephalotus » Apr 29 2020 3:58am

I do recommend "semiflexible" panels wit Sunpower cells. Use moduls with PTFE coating, NOT PET coating.
Do NOT treat them as semiflexible panels, they need a very riged surface to mount them. If you let them flex the cells will brake and output power will degrade quicky.

Do NOT use high voltage moduls with lots of cells in series. This is bad for partial shading and you will see lots of partial shading on your ebike. Use low voltage panels at around 15-20 volt.

Use MPP Boost chargers, I do recommend Genasun. They are lightweight, efficnet and have quick MPP tracking wich is very important for mobile applications. Ideally you would use one charger per module to limit effects of partial shading. This will get expensive though.

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aluminumwelder   10 mW

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Re: One stop for solar charging ebike info?

Post by aluminumwelder » Jul 15 2020 10:09am

I am putting together a system using 4 sunpower 170v panels which will make a roof above my trike that is about 4x10 ft in size. I'd make it so the panels can be taken off easily and they would probabaly fold in half so 4x5' for easier storage. they have a 2 year mechanical 5 year output warranty. each panel is about 4x2.5' in area and 30vmp. I am trying to decide whether to go with a 2s2p array which will give me 60v and use a midnight solar 150v KID MPPT controller for $300 or should I use 4 GenaSun Mppt controllers which will cost more like $800 or perhaps these cheap chinese Mppt controllers I see GrinTech is reselling for $75 each, or $30 direct from china?

This is just a fun hobby project, I have installed residential solar systems, but never a battery powered solar system that is mobile. Would be just be used for riding around town.

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Re: One stop for solar charging ebike info?

Post by john61ct » Jul 17 2020 5:34am

Voltage of panels is one thing.

Finding solar controllers that output at your pack voltage is another.

Might need a DCDC boost converter, with a HVC for charge termination when (if ever) the pack gets full

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Re: One stop for solar charging ebike info?

Post by Balmorhea » Jul 17 2020 5:53am

It seems to me that if you have a series PV array that puts out slightly more voltage than your battery’s fully charged voltage, and a trustworthy BMS that will cut off the charger at the prescribed maximum, and your battery can charge at more current than the PV array is capable of putting out, then you can simply plug the array into the charge port of your battery and let it do its thing. Stick a diode in there and sacrifice half a volt so the battery doesn’t discharge into the panel.

It might not be as efficient overall as MPPT, but it’s for sure simpler and easier.
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Re: One stop for solar charging ebike info?

Post by amberwolf » Jul 17 2020 11:26am

Balmorhea wrote:
Jul 17 2020 5:53am
Stick a diode in there and sacrifice half a volt so the battery doesn’t discharge into the panel.
From what I can tell, prebuilt panels in the last several years at least, probably longer, come with the diode built onto the panel.
It might not be as efficient overall as MPPT, but it’s for sure simpler and easier.
And it does work; I tested it with four old crappy panels I have here.

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Re: One stop for solar charging ebike info?

Post by john61ct » Jul 17 2020 12:40pm

Sure you can do that.

But even the most "trustworthy" BMS costing many hundreds of dollars will occasionally / eventually fail.

A basic SC is like $30 or $40, couple takeout meals.

A top notch one maybe $130 or so.

Skimping on that, if (when) the BMS fails, you cook your (presumably expensive) House bank.

Other than balancing functions if you use a BMS for that,

BMS should only be used as a backup failsafe, for when the primary "user space" devices fail,

Their protections should otherwise never be engaged except for testing purposes (trust but verify 8-).

Of course if you are genuinely poor, recycling scrap starter batts as your House bank

then it doesn't matter so much, reliability is not such a priority, redneck engineering is perfectly appropriate.

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aluminumwelder   10 mW

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Re: One stop for solar charging ebike info?

Post by aluminumwelder » Sep 13 2020 8:45pm

I got these MPPT charge controllers from China. They took a small order of only 6 units. they are designed for gold carts, ebikes with 48 or 60v battery packs. Big aluminum extrusion Not as small as the $200 Genasun units but they were $17. for that price I'll take the extra 4 lbs of weight they add.

https://www.alibaba.com/product-detail/ ... 2fc2fsH37C

Got the solar panels on order off ebay.
https://www.ebay.com/itm/SunPower-170W- ... SwkAhfDMQ-

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Hwy89   10 kW

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Re: One stop for solar charging ebike info?

Post by Hwy89 » Sep 13 2020 10:58pm

Aluminumwelder, please come back and give a review on the Chinese MPPT charge controllers. I hope they are a good product.

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Re: One stop for solar charging ebike info?

Post by JackFlorey » Sep 13 2020 11:06pm

amberwolf wrote:
Jul 17 2020 11:26am
Balmorhea wrote:
Jul 17 2020 5:53am
Stick a diode in there and sacrifice half a volt so the battery doesn’t discharge into the panel.
From what I can tell, prebuilt panels in the last several years at least, probably longer, come with the diode built onto the panel.
They have bypass diodes not anti-backfeed diodes.

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Re: One stop for solar charging ebike info?

Post by john61ct » Sep 13 2020 11:41pm

What is a gold cart?

Balmorhea   1 MW

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Re: One stop for solar charging ebike info?

Post by Balmorhea » Sep 14 2020 1:01am

john61ct wrote:
Sep 13 2020 11:41pm
What is a gold cart?
Don’t ask him; ask Siri.
aluminumwelder wrote:
Sep 13 2020 8:45pm
I got these MPPT charge controllers from China. They took a small order of only 6 units. they are designed for gold carts, ebikes with 48 or 60v battery packs. Big aluminum extrusion Not as small as the $200 Genasun units but they were $17. for that price I'll take the extra 4 lbs of weight they add.
You might as well keep all six handy. You’ll likely need the replacements before long (based on my plentiful experience of cheap Chinese mail order goods).
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Re: One stop for solar charging ebike info?

Post by solarEbike » Sep 15 2020 6:36pm

Hwy89 wrote:
Sep 13 2020 10:58pm
Aluminumwelder, please come back and give a review on the Chinese MPPT charge controllers. I hope they are a good product.
These look awfully similar to the one Alex reviewed except they added under-speced 12v and 5v outputs (6w and 5w only?!). You can buy just one unit for US$30 on eBay or AliExpress including shipping. Search “boost solar charge controller”

[youtube]tN6ykK9Q-CQ[/youtube]
Current setup: SWB recumbent, Grin v1 5t DD hub w/ Statorade, Phaserunner, 6x LiGo battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram

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Re: One stop for solar charging ebike info?

Post by John in CR » Sep 16 2020 2:41am

A consideration if a giant wind catching wing above you isn't practical, but by all means install whatever is practical to capture what you can while riding, is to also carry a nice stack of the thin flexy type panels in some kind of protective box or rack while riding. Then plan a nice long lunch at mid-day with the panels laid out nicely on a rigid frame to angle directly at the sun to pick up 1-2 hours of prime sun. It wouldn't be hard or too expensive to get a kwh of charge that way.

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Re: One stop for solar charging ebike info?

Post by kg6gfq » Sep 25 2020 1:03am

Here are some links & notes I pulled together during my last research dive into solar e-bikes. Between the youtube channel, the presentation from the GRIN / ebikes.ca folks, and the info on the GRIN & Sol Mobil websites you should be able to get a pretty good notion of how the Sun Trip bikes are wired up. GRIN sells a solar conversion kit, and Sol Mobil sells some of the parts, and from looking at their websites I bet both would be willing to answer questions.


Ok, links & notes:

how to charge your ebike with solar panels - https://www.youtube.com/watch?v=X78VCsY ... e=youtu.be
genasun chargers are expensive - there are cheaper ($50) alternatives, but not as good
use SunPower cells - there are varying degrees of efficiency
he used SunBeam Systems, but any brand with sunpower cells is good
at least 80W panels, ideally around 160W (maybe 200)
lots more videos from this user w/ details about building and testing a solar trike

sun trip presentation from GRIN / ebikes.ca folks - https://www.youtube.com/watch?v=15HHLY4BfA4
1kwh battery max allowed for the trip (about double standard ebike battery?)
400W solar panel max allowed for the trip (550 tandem)
tilting panels didn't make much difference when riding since it's mostly an east-west trip
even on sunny day, never hit more than 80% of panel's power rating
over the course of a sunny day, they could get 3000wh from their 550w panels (=six standard 500wh batteries)
even on the worst, rainiest day, they got 1000wh from the panels
most riders on the trip averaged 4wh/watt (e.g. if you need 1000wh over the course of the day, use a 250w panel)
solo riders get about 1km/8wh (GRIN normally quotes 1km/10wh for average riders - sun trippers were pedaling harder)
tandems get about 1km/14wh
don't expect dramatic improvements in battery tech
do expect significant improvements in photovoltaic tech (currently 25% is really good, but cutting edge is 40% efficient)
the difference between a 22% efficient panel and a 27% efficient panel is doubling or tripling the cost

sol mobil - shop in appalachia owned by Sun Tripper, sells the good charge controller - https://www.sol-mobil.com/

solar bicycle camper / pedal powered mobile home - a little silly, but fun - https://www.youtube.com/watch?v=hR-E55RZqQs

czech solar team - http://czech-solar-team.com/

solar trike conversion in comments - https://www.instructables.com/id/Sun-Ba ... e-Upgrade/

one sun trip winner - https://www.vanhulleraf.be/cycle



Sorry that's not more organized; I hope some of it is helpful!

-Darin


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