Go Back  Bike Forums > Bike Forums > Electronics, Lighting, & Gadgets
Reload this Page >

Using a Solar Panel and Battery Instead of a Dynamo Hub to Power Running Lights

Notices
Electronics, Lighting, & Gadgets HRM, GPS, MP3, HID. Whether it's got an acronym or not, here's where you'll find discussions on all sorts of tools, toys and gadgets.

Using a Solar Panel and Battery Instead of a Dynamo Hub to Power Running Lights

Old 07-26-15, 07:20 AM
  #1  
Tyler Mock
Thread Starter
 
Mock602's Avatar
 
Join Date: Jul 2012
Location: Philadelphia, PA & Syracuse, NY
Posts: 7

Bikes: 1988 Giant RS930, 2015 Surly Disc Trucker

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Using a Solar Panel and Battery Instead of a Dynamo Hub to Power Running Lights

Hello everyone,

I want to use a solar panel-battery combination instead of a dynamo hub to power dynamo-powered lights (Busch and Muller Luxos U Lumotec IQ2 and the Busch and Muller Toplight Line Plus). To provide some context, below is a rough schematic I drew:



My plan is to wire the front and rear lights as one normally would with a dynamo. However, the difference is that a solar panel will be hooked up to an external battery and the connection between the battery and the headlight will be a modified iphone USB charger cable with the iphone connection part cut off and spliced onto a 2.8mm male spade connector: 2.8mm Male Spade Connector - Longleaf Bicycles.

The problem I am trying to wrap my head around is that Busch and Muller lights are 6 volts and a USB cable has a maximum output of 5V. Will this be a problem? Should I try a different cable other than a USB to hook up to an external battery? Should I even try this crazy contraption?

I haven't decided on the solar panel-battery combination yet, but I am looking at GoalZero and Anker. For all intents and purposes, let's assume getting a hub dynamo is not an option. Any and all comments are greatly appreciated.

Thanks,
Tyler
Attached Images
File Type: jpg
IMG_2582.jpg (93.3 KB, 36 views)
Mock602 is offline  
Old 07-26-15, 07:26 AM
  #2  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,421

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5639 Post(s)
Liked 2,267 Times in 1,271 Posts
It's not only a question of voltage. You have to consider wattage, and calculate the size of the solar array needed to produce that.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is online now  
Old 07-26-15, 08:07 AM
  #3  
Tyler Mock
Thread Starter
 
Mock602's Avatar
 
Join Date: Jul 2012
Location: Philadelphia, PA & Syracuse, NY
Posts: 7

Bikes: 1988 Giant RS930, 2015 Surly Disc Trucker

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FBinNY
It's not only a question of voltage. You have to consider wattage, and calculate the size of the solar array needed to produce that.
Certainly an important consideration, but what I am unsure of is whether a max 5V USB line will be able to power the lights rated at 6V. Will they just be slightly dimmer or will they not work at all because they are not receiving the proper voltage?
Mock602 is offline  
Old 07-26-15, 08:45 AM
  #4  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,353 Times in 860 Posts
Going to stay in one place a lot to charge batteries,? And dont mind a 2 + square foot solar panel

that you keep adjusting as the sun moves across the [clear?] sky so as to be perpendicular to the sunlight.

great.
fietsbob is offline  
Old 07-26-15, 10:55 AM
  #5  
Senior Member
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 6,432
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 539 Post(s)
Liked 44 Times in 38 Posts
I think your bigger problem - aside from regular solar panel issues - is that as I understand it, dynamo lights take alternating current, while batteries put out direct current. If I remember right there is a seperate model of the Edelux II they made for bike that are powering it from a battery, because it takes different electronics.
PaulRivers is offline  
Old 07-26-15, 11:51 AM
  #6  
Senior Member
 
catgita's Avatar
 
Join Date: Oct 2014
Location: Long Beach
Posts: 765

Bikes: Fitz randonneuse, Trek Superfly/AL, Tsunami SS, Bacchetta, HPV Speed Machine, Rans Screamer

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 100 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
No go on DC power of Dynamo lights. DC will burn out the capacitor drive circuitry.

You would probably be better off with USB battery lights, which can all be done solar with off the shelf parts, even if they don't have the good optics. One caveat, USB lights often can't take external power with the light turned on (charge or run, not both) so if you need long run times you may need two lights. Or you could hack a light that uses external batteries.
catgita is offline  
Old 07-29-15, 02:32 PM
  #7  
Senior Member
 
saturnsc2's Avatar
 
Join Date: Aug 2004
Location: Cleveland, Ohio
Posts: 392

Bikes: 1982 Huiffy 10-speed

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
why not just use a dynamo of some sort? be free of batteries & not have to worry about run time. you would have to leave your bike in the sun all day to charge. what's the point of that? a solar panel & batteries are much more expensive than a small bottle dynamo...
saturnsc2 is offline  
Old 07-29-15, 08:13 PM
  #8  
Senior Member
 
Join Date: Sep 2007
Location: Far beyond the pale horizon.
Posts: 14,215
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 4197 Post(s)
Liked 1,297 Times in 899 Posts
Originally Posted by Mock602
Certainly an important consideration, but what I am unsure of is whether a max 5V USB line will be able to power the lights rated at 6V. Will they just be slightly dimmer or will they not work at all because they are not receiving the proper voltage?
The line/cable should be able to handle 6 volts (it's not that different than 5). Amperage should be the concern.

The issue is that the USB power source will be limited/regulated to be 5 volts. That's a requirement of it being USB. USB has a standard amperage of 500 mA but some chargers supply 2.1 A.

Last edited by njkayaker; 07-29-15 at 08:24 PM.
njkayaker is offline  
Old 07-30-15, 10:57 AM
  #9  
RR3
Banned
 
Join Date: Aug 2014
Posts: 1,226
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Good tips on using solar to power off-grid cyclign tours...

https://www.crazyguyonabike.com/doc/?doc_id=9258
RR3 is offline  
Old 08-20-15, 07:56 PM
  #10  
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 16,847

Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1851 Post(s)
Liked 653 Times in 497 Posts
Originally Posted by Mock602
Certainly an important consideration, but what I am unsure of is whether a max 5V USB line will be able to power the lights rated at 6V. Will they just be slightly dimmer or will they not work at all because they are not receiving the proper voltage?
Depending on the light source technology it might or might not get dimmer. I'd say target a system voltage maybe 5 to 10% larger than what the light needs to meet specs. The battery voltage pumps up and down as the battery state of charge rises and falls. The solar array open circuit voltage changes with solar intensity (cloudy days) and the short circuit current is affected by solar array temperature. This is by no means a simple, constant voltage setup.
Road Fan is offline  
Old 08-21-15, 07:50 AM
  #11  
Señior Member
 
ItsJustMe's Avatar
 
Join Date: Sep 2005
Location: Michigan
Posts: 13,749

Bikes: Windsor Fens, Giant Seek 0 (2014, Alfine 8 + discs)

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 446 Post(s)
Likes: 0
Liked 8 Times in 7 Posts
I think the main flaw to all this is that you're trying to integrate two or three technologies, each of which was designed for a specific purpose, and none of those purposes really match up.

Honestly I'd do a ground up redesign. As is you're going through two or three voltage converter stages already and none of them match.

For instance, that 5V output - it's not natural from the cells, it's regulated to 5 volts by circuitry. If you did a full redesign, you could just as easily have that be 6 volts. Heck, you could have it put out 6 volts AC if you liked.

I don't buy that DC is going to bother a system designed for AC, because that system is going to have to rectify back to DC in order to charge capacitors and run the LED anyway. A lot of systems that normally take AC will work just fine on DC if you feed it to them, because the very first thing they do with AC is to rectify it back to DC and smooth it out with a capacitor. If you feed it DC it won't know the difference. But I don't know the specifics of dyno lights.
__________________
Work: the 8 hours that separates bike rides.
ItsJustMe is offline  
Old 09-23-15, 05:10 AM
  #12  
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 16,847

Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1851 Post(s)
Liked 653 Times in 497 Posts
Originally Posted by ItsJustMe
I think the main flaw to all this is that you're trying to integrate two or three technologies, each of which was designed for a specific purpose, and none of those purposes really match up.

Honestly I'd do a ground up redesign. As is you're going through two or three voltage converter stages already and none of them match.

For instance, that 5V output - it's not natural from the cells, it's regulated to 5 volts by circuitry. If you did a full redesign, you could just as easily have that be 6 volts. Heck, you could have it put out 6 volts AC if you liked.

I don't buy that DC is going to bother a system designed for AC, because that system is going to have to rectify back to DC in order to charge capacitors and run the LED anyway. A lot of systems that normally take AC will work just fine on DC if you feed it to them, because the very first thing they do with AC is to rectify it back to DC and smooth it out with a capacitor. If you feed it DC it won't know the difference. But I don't know the specifics of dyno lights.
Yes, dyno lights need an internal rectifier, so it might work. But what about the voltage drop through the rectifier? Need 6.3 dc for good lighting performance, and there will be at least one diode drop (0.3 to 1.0, depending). So the internal voltage available for the light source is now down (from the 5 volts) to 4.0 to 4.7 or so. But if the AC rectifier uses synchronous technology, there's minimal voltage drop, but you still don't have 6 volts.

Biggest challenges are the diverse technologies and the use cases: AC light sources, regulated USB direct current plug ins, working with USB devices and without, the daily usage life cycle considering daily light/dark cycle, type of bike ride (24 hour rando or endurance versus just riding around), managing battery depth of discharge, ... optional plug in and onward.

Based on the AC voltage issue, I'd look hard for a comparable quality DC headlight, or I'd modify an AC light like a Lumos to bypass the internal rectifier but not the over voltage limiter.

But I think I overall agree, this would be done best as a clean-sheet design, unless the clean-sheet Edelux is in the budget.

BTW, I think the battery is going to weigh about ¾ pound, if you want it to run USB and lighting for 8 hours.

Last edited by Road Fan; 09-23-15 at 05:17 AM.
Road Fan is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Gypsy1
Electronics, Lighting, & Gadgets
24
03-10-19 12:22 PM
Tandem Tom
Electronics, Lighting, & Gadgets
29
11-13-17 08:24 AM
corrado33
Electronics, Lighting, & Gadgets
26
11-10-14 11:47 PM
downtube42
Electronics, Lighting, & Gadgets
5
10-11-13 07:26 PM
conradpdx
Classic & Vintage
2
01-25-13 05:52 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.