How to Solar Charge an Electric Bicycle

[dnmun]

if the solar panels are wired directly to the battery then the solar panel voltage will not exceed the voltage on the battery until the battery hits the HVC on the BMS.

when the BMS resets then the high open circuit voltage will immediately drop to the same voltage as the battery.

there is no situation where the solar panels are at a different voltage from the pack except at HVC and when the panels are dark and there is not enuff voltage to charge the battery.

in that case the diode on top of the solar collector keeps the current from flowing out of the battery and into the p-n junction of the solar cell.

for a 58V DC final voltage you should use an 80V diode at least.

 

[LockH]

"Currently, Marissa Muller is making the journey with a solar bicycle. Having started in Ventura, California, and plans to finish in Washington D.C., Muller traveled through Prescott on Wednesday and Thursday, June 3-4, before leaving for Sedona."
http://dcourier.com/main.asp?SectionID=1&SubsectionID=1&ArticleID=146193

(News via Prescott, AZ "DC Courier".)

 

[Cowardlyduck]

I did it like this...
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=57751&start=125#p1057018

I'm at work, it's outside, charging now.

Cheers

 

[mountain biker]

HOLY COW. nice man.....tell us more....is that directly wired,,,whats your voltage from the panel and watts amps volts....etc....i like it.
perfect bug out vehicle.

 

[Cowardlyduck]

HOLY COW. nice man.....tell us more....is that directly wired,,,whats your voltage from the panel and watts amps volts....etc....i like it.
perfect bug out vehicle.

Thanks! To be brief it's basically:
-18W - 20.5% efficient 12V panel
-CC-CV - 5A capable DCDC converter
-2x Schottky Diodes
-Cheap '150A' Watt meter
Plus a bunch of JST 2.5mm connectors and 20AWG silicone wire.

Check the link for more info/pictures.
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=57751&start=125#p1057018

Cheers

 

[ScooterMan101]

I spent enough time reading just the first page of posts for this thread, so to save time,

A custom made MPPT charge controller is the answer .

Anyone here, especially here in the U.S. know of anyone who can make a small / light weight MPPT Controller ?

I have thought about pulling a trailer with solar panel / solar cells, not because of trying to save money from my electric bill, because in reality , it would cost much more to buy a panel/cells and make the trailer, than it would to put the panels on your house, albeit , for the few of you who are lucky enough to live in a house and not an Apartment !
I want to do it , because where I ride , pulling a trailer gives the car/truck driver something bigger to drive around , meaning more space for you on the bike. ( I have done a lot of pulling a trailer without solar on it and noticed drivers passing with more space between me and them) .
and I also want to do this to extend range, Li-Ion and Li-Poly packs are expensive !
a smaller pack and solar cell trailer, with a custom made MPPT Charge controller will give me the range I really want to go on the bicycle .

 

[jaunty]

I agree scooterman...24V charge controllers are pretty common though (i have one).
Here is a genasun designed for lithium...even charges at the lower voltage...hmmm
http://genasun.com/all-products/solar-charge-controllers/for-lithium/gvb-8a-li-lithium-solar-boost-controller/



cowardlyduck: nice ride!

If the panel is 18W charging at 12V you're getting 1.5A charge BUT after the DC-DC converter and other losses you're looking at 0.3 Amps. Not too bad. So your 13AH battery would charge in 43 hours in full sun. So you're looking at about a 20% capacity charge in a day at work. Does that sound about right? They make some nifty fold-up/roll up panels now that you could easily transport around.

 

[d8veh]

I spent enough time reading just the first page of posts for this thread, so to save time,

A custom made MPPT charge controller is the answer .

Anyone here, especially here in the U.S. know of anyone who can make a small / light weight MPPT Controller ?

I have thought about pulling a trailer with solar panel / solar cells, not because of trying to save money from my electric bill, because in reality , it would cost much more to buy a panel/cells and make the trailer, than it would to put the panels on your house, albeit , for the few of you who are lucky enough to live in a house and not an Apartment !
I want to do it , because where I ride , pulling a trailer gives the car/truck driver something bigger to drive around , meaning more space for you on the bike. ( I have done a lot of pulling a trailer without solar on it and noticed drivers passing with more space between me and them) .
and I also want to do this to extend range, Li-Ion and Li-Poly packs are expensive !
a smaller pack and solar cell trailer, with a custom made MPPT Charge controller will give me the range I really want to go on the bicycle .

You don't need a custom one. You can get them off the shelf:

http://www.aliexpress.com/store/product/MPPT-Boost-Solar-Charge-Controller-step-up-90V20A-charge-all-kinds-battery/515737_1708497647.html

 

[sharkmobil]

Nice one. Thanks.

Any leads on the good high voltage DC-DC boost converters (36v->400v, 300w)?

 

[Cowardlyduck]

cowardlyduck: nice ride!

If the panel is 18W charging at 12V you're getting 1.5A charge BUT after the DC-DC converter and other losses you're looking at 0.3 Amps. Not too bad. So your 13AH battery would charge in 43 hours in full sun. So you're looking at about a 20% capacity charge in a day at work. Does that sound about right? They make some nifty fold-up/roll up panels now that you could easily transport around.

Thanks!
Yeah, your pretty spot on, although it's winter here now, so not getting anywhere near full performance yet. Highest momentary output I've seen so far after the DC-DC was around 2.4W so ~0.05A.
So I'm only getting around 14-15Wh, or 2.5% per day currently...that's still over one extra km in range, which is exactly what I need at the moment with my longer than previous 45Km round trip commute. The other part is the panel acts as a wind break, so my cruising efficiency is better. I've arbitrarily noticed about a 50-100W reduction in power consumption when cruising at ~40kph on the flats. That makes a far bigger difference to my range than the charging does at the moment.

Cheers

 

[ScooterMan101]

I spent enough time reading just the first page of posts for this thread, so to save time,

A custom made MPPT charge controller is the answer .

Anyone here, especially here in the U.S. know of anyone who can make a small / light weight MPPT Controller ?

I have thought about pulling a trailer with solar panel / solar cells, not because of trying to save money from my electric bill, because in reality , it would cost much more to buy a panel/cells and make the trailer, than it would to put the panels on your house, albeit , for the few of you who are lucky enough to live in a house and not an Apartment !
I want to do it , because where I ride , pulling a trailer gives the car/truck driver something bigger to drive around , meaning more space for you on the bike. ( I have done a lot of pulling a trailer without solar on it and noticed drivers passing with more space between me and them) .
and I also want to do this to extend range, Li-Ion and Li-Poly packs are expensive !
a smaller pack and solar cell trailer, with a custom made MPPT Charge controller will give me the range I really want to go on the bicycle .

You don't need a custom one. You can get them off the shelf:

http://www.aliexpress.com/store/product/MPPT-Boost-Solar-Charge-Controller-step-up-90V20A-charge-all-kinds-battery/515737_1708497647.html

WoW things have changed in the last 8 years, now the Chinese are making MPPT Charge Controllers, and at a great price point. No wonder I could not find the American Mgf. that use to make custom ones 8 years ago.

I did look at that MPPT Boost Charge Controller you linked to , however when I looked at the charge voltage for a 48 volt pack, it charges at 57.6 volts, My Li-Poly Charger charges at 54.6 volts/2 amps.
I wonder what charging at 57.6 volts do to Li-ion / Li-Poly Batteries ?

 

[zener]

I did look at that MPPT Boost Charge Controller you linked to , however when I looked at the charge voltage for a 48 volt pack, it charges at 57.6 volts, My Li-Poly Charger charges at 54.6 volts/2 amps.
I wonder what charging at 57.6 volts do to Li-ion / Li-Poly Batteries ?

There is a poti where you can set any end-voltage up to 90V.
I would also like to buy this in combination with a Sunpower (USA) :wink: 180W flexible solar panel. Should give me about 1KWh of free charge when i park my ebike a day in the sun.
Is it really a real MPPT? I have seen many fake ones from China. I wait with my buy till someone did a review from this $35 MPPT charger.

 

[LockH]

"The Solar Energy Revolution: Past the Point of No Return"
http://www.fool.com/investing/gener...nergy-revolution-past-point-of-no-return.aspx

 

[LockH]

"Rayton’s new super-efficient, affordable solar panels could trump fossil fuels"
http://inhabitat.com/raytons-new-super-efficient-affordable-solar-panels-could-trump-fossil-fuels/

 

[kd8cgo]

Lock posted above about the Marissa Muller solar trip, I was checking it out, as I am just starting a solar trailer build atm. She's on a Specialized Turbo @250W power output, and is pulling along 240Wp of custom lightweight panels. What I thought was cool was in this interview she mentioned an average speed about 19mph and a flat/sunny end-of-day performance of about 75% battery remaining. That is flipping awesome, especially on a ~500Wh pack! She's a marketing type, so I'm sure that the sponsors' will be held in high regard for the duration of the trip, but I was pleased with that claim, if accurate. And of course, she was traveling the southwest USA in peak season as well, absolute killer insolation in that region.

Luke has already mentioned that grid-tie is the most efficient use of private solar investment for all energy use cases, including electric transport - which I 100% wholeheartedly agree with, and simultaneously would never invest in. I'm looking to maximize independence and decentralization as the primary variable for system designs - which means off grid systems, both stationary and mobile. Cost and energy efficiency take a hit though, while they ride in the backseat.

 

[LockH]

"Roy Rivera is a disabled man who lives on a fixed income in Sacramento – and he’s also the first California resident to receive a free rooftop solar system. But he won’t be the last. Thanks to legislation first introduced by Senator Kevin de León, the Oakland-based non-profit GRID Alternatives plans to give 1,600 free solar panels to California’s poorest residents by 2016. The initiative was launched with funds gathered under the Greenhouse Gas Reduction Fund (GCRF), the state’s cap-and-trade program designed to discourage carbon dioxide emissions."
http://inhabitat.com/california-dishes-out-free-solar-panels-to-its-poorest-citizens/

 

[veloman]

I have a homebuild PV panel that puts out 28v max, or about 20v at peak power. I was using a step up converter to charge some of my batteries, but that would pull the panel voltage down to 8v, and wasn't efficient (and made an annoying high frequency noise). So instead, I hooked up just the panel, in series with a 48v charger to charge my 20s Leaf pack. Current ranges from 0.3a to 1.6a on this partly cloudy day. I measured the efficiency of my charger plugged into the wall, and it seems quite good.
So, this setup seems to be the best way to go if you only have a low voltage panel and don't want to invest any more money in a mppt. My Leaf battery is 60ah on the motorcycle, so I never worry about overcharging it.

 

[LockH]

"Solar-Powered Bicyclist Treks Across Country, Stops In Fort Smith" (Arkansas):
http://swtimes.com/news/solar-powered-bicyclist-treks-across-country-stops-fort-smith

Her website:
http://www.marissamuller.com/

 

[launchpad]

Been off forum for some time. Time to re-engage as we are solarizing our second trike.

Our first effort (2013) is below.



Specs are:
Greenspeed GTT (including SS couples - packs away in a bike box - seats in a bag)
240W Solar Panels on custom made frame.
Genasun GV Lithium Boost MPPT controller to get maximum juice out of cells
Sky RC Watt Meter to measure power going into battery
Cycle Analyst 3 - to monitor power consumption and manage torque pedal assist. Speed limited to local laws of course. CAv3 = best thing since sliced bread
Thun Torque sensor on front crank - this is a true pedal assist and greatly extends battery life while keeping us honest
Golden Motor Magic Pie 3 - the solid aluminum casted wheel good for this trike.
36V 20A LiFePO4 battery.



We took the beast on the CQ2013. Up and down the Palmerston Range in North Queensland. One of the toughest CQ rides yet. 8 days. Long hill going up!







Does the "on the road charging work"? Damn right it does. We average about 100W.h charging, which is the same as our average consumption. It is not uncommon for us to do a 60 km ride around Brisbane and return with a full battery. Granted our Brisbane tracks have only modest hills, we have sunny weather and we will stop for lunch etc. Avg speed around 20 - 25 km/h.

Most beneficial side effect: THE SHADE ! Particularly riding on hot QLD days. We come off far less fatigued on long rides.

My next challenge is to convert a Magnum into a Solar Assist. The big thing we have learnt from the tandem is that Flexible Solar panels on aluminium backing are not reliable. Lose one cell, lose the panel. We are now making our own solar cells and panels with a home laminator. Works like a charm in trials and we can replace just once cell should we need. Now to put the theory into practice.

Cheers.

 

[LockH]

Dang. No "Thumb Up" STILL on Planet ES.

But life-long sailor has a question please? NO windy days??? (Just curious about "things" getting out of control due to "cross-winds"/"head winds"... all things "wind-related".)

 

[launchpad]

Just curious about "things" getting out of control due to "cross-winds"/"head winds"... all things "wind-related".

Never been an issue. Low profile + our total weight with both adults is around 200 kg + plus we are a cruiser, not a racer.

Our CoG is naturally higher and it is advisable to keep it on 3 wheels when cornering (else Stoker gets narkey!).

We get more wind effect on our motorcycle.

 

[LockH]

`Kay. Cool LP. "But" (again), added weight aka "mass" adds energy required to accelerate or "climb" any hills?

 

[launchpad]

Sure. The array adds about 15kg. But it more than pays for itself energy-wise.

The proof is in the pudding. Day 3 ride of CQ2013 looked like this:



Many conventional riders thought one of the toughest days they had encountered. We survived it really well as we stayed "shaded" and monitored our power consumption to ensure we had enough reserves. The last thing we wanted to do is run out of power. This is one electric jalopy that you don't want to peddle up hill without assist.

It was simply a matter of calculating our power consumption vs speed and distance and keeping within our quota.

Coming down the hill into Mossman we were generating 2Kw from regnerative power.

The other thing is the array is removable. No need for short trips if power is not the problem. But in hot, direct sun it's a real bonus for comfort and fatigue reduction.

 

[LockH]

Good to hear! I'm tending towards a "velomobile" coroplast body papered with Rayton "thin film" PV strips. (See above/earlier in this thread. More energy consumption cooling w/"air conditioning" on the hottest days). Weight of only 15kg seems "doable". With more "free energy" via an adjustable sail (w/more thin film) to grab more "solar" via winds. At least all may make any PV cells less "steal-able". Maybe better cover on rainy days too with this shell approach.
[youtube]GLqxDm3_GZY[/youtube]

EDIT: And these folks:
[youtube]xx94cq2GZw4[/youtube]

 

[ddk]

Been off forum for some time. Time to re-engage as we are solarizing our second trike.
... Now to put the theory into practice.

Cheers.

It's so good to see you still riding. And building yet another (one can never have enough trikes- lol.)
My panels are currently part of a porch now, but your experience adds evidence of needing about 300W of flat-mounted panel (depends on latitude and # of sun-drenched days) My 300W panel averaged more like 75W but my latitude is 42degree north where you're what? 20 degrees south?

I might go about adding cells to MPPM velo, but it only' has a 1600mm x 736mm area so I've been (slowly) trying to source efficient cells.

@ sailerboy, even with the (relatively) huge panels of MyPersonalPopeMobile, living on the gusty coast, windage just isn't a big issue. I also travel at less than 30kph.
...still I do so prefer a stiff tailwind to a gusty headwind.