Author Topic: Solar gadgets + AA's  (Read 9378 times)

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #25 on: January 25, 2011, 02:37:49 pm »
Quote from: The nice lady at Power Monkey
You cannot charge a device from the Monkey or the Chimp while it is charging from a solar panel.

You can however charge a device from the panel direct with the smart phones you may need the solar nut to keep the power flow at an even 5v rate.

So there you go.  The lipoly battery stage is needed in everything and there's no sneakin' around it.  (Obviously you'd use a USB AA/AAA charger to slurp the Nut dry for other toys)
It takes blood and guts to be this cool but I'm still just a cliché.
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Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #26 on: January 25, 2011, 02:42:28 pm »
Quote from: The nice lady at Power Monkey
you may need the solar nut to keep the power flow at an even 5v rate.

Go directly to year 8 physics.  Do not pass 'Go'.  Do not collect 200 Joules per coulomb...


It's Stephen Fry all over again!
Careful, Kim. Your sarcasm's showing...

Re: Solar gadgets + AA's
« Reply #27 on: January 25, 2011, 03:02:15 pm »
Quote from: The nice lady at Power Monkey
you may need the solar nut to keep the power flow at an even 5v rate.

Go directly to year 8 physics.  Do not pass 'Go'.  Do not collect 200 Joules per coulomb...


It's Stephen Fry all over again!
:facepalm:

One of my children was talking about electricity and units. Her teacher had described using a circuit with a '50 joule' lightbulb.
I suggested that daughter might have missheard, but she was adamant.
<i>Marmite slave</i>

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #28 on: January 25, 2011, 03:12:20 pm »
Well, yes.  But for most punters, "...to keep the doofer at the right dooferage for your thingummy" would have conveyed just as much.   ;)
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #29 on: January 27, 2011, 08:07:34 am »
So, after a second look over the Powermonkey stuff, it's safe to class my device as a "heavy drain" type (iphone 4 and the like; at least it'll apply while running GPS and internets), so they're saying use a powermonkey eXplorer (stupid names argh) -- the bigger smarter battery plus a panel.  That'll run-through and may even grobble enough charge to tickle some AAs.

It's also expensive enough to go homebrew!
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

The Mechanic

Re: Solar gadgets + AA's
« Reply #30 on: January 27, 2011, 02:13:10 pm »
Don't you people have homes to go to?

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #31 on: March 25, 2011, 07:56:49 pm »
Right.  Spoke to a chap who tours around the Caledonian Wastes and he really rates his Powermonkey Explorer, but the spec sheet has a 2200 mAh battery in the guts.  That's weaksauce (my Vapex AA's are 2900 mAh each, so that'd give a meh charge to a set of these bad boys, even though it would probably fill the phone at 1450 mAh). 

So, homebrew.  It's payday, after all. 

Ada has this solar panel, which is a beast: http://www.adafruit.com/index.php?main_page=product_info&cPath=44&products_id=200  -- 6v 300mA, and also fits nicely in any handlebar bag maptrap.  It roundly spanks the PowerMonkey solar, which is best of the readymade class.

All I need is an AA/AAA charger which will mate up to it.  I wonder if an ordinary USB charger would take those volts?
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #32 on: March 25, 2011, 08:05:26 pm »
Bung it through a low-dropout 5V regulator and you're in business.  Sort of.  The charger will probably be expecting to be able to pull at least 500mA (as per USB spec) and might refuse to charge when the voltage falls off.  Plus you've got to de-rate the panel to allow for Typical British Weather (that's the real gotcha).

Have a google around for solar charging circuits, though.  This isn't the first time someone's tried to do this.  At that sort of current you can probably get away with putting the panel straight across a couple of cells in series (with blocking diode so it doesn't discharge in the dark).  The tricky bit there is knowing when to stop - when the battery is charged it'll start to cook.

Careful, Kim. Your sarcasm's showing...

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #33 on: March 25, 2011, 08:26:30 pm »
It's the cookery that makes me sad. 

Ooh, Voltaic have done the hard work for anyone with a pile of cash: Fuse is two of their big panels and a battery, all rigged up for bikes.  Voltaic Fuse Solar Charger
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #34 on: March 26, 2011, 12:14:05 am »
Now that, I like.

First thing I've seen that's remotely near my back-of-the-envelope calculations for what constitutes a reasonable amount of power and storage.

I'm still lusting after Powerfilm marine-grade flexible panels in the 5W range.  Reckon that ought to be about as good as[1] a dynamo, but without the pedalling.  And the sheer over-engineering of the things totally does it for me.


[1] On the assumption of bright sunshine being about as common as riding fast while touring, so you're going to get a couple of Watts on average.
Careful, Kim. Your sarcasm's showing...

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #35 on: March 30, 2011, 10:50:38 pm »
I'm still lusting after phased plasma rifles in the 40W range.

ftfy  8)

I have foolishly added the word "circuit" to my googles and my god it's full of nerds.  :thumbsup:

And content farms.   :sick:

So... it'd be fairly simple to rig a 5v regulator for a 6v panel with an LM2941 or its low-dropout ilk.  That makes a "USB-erizer" a matchbox dongle, easy to connect a USB charger too as long as it was useful at low voltages.  Hm.  Isn't there anything that just scrapes dribs and drabs of electrickery and pumps them in regardless?  Or am I confusing electrons and water again?

Edit to add (after sucking on Ada's fount of boffinage): 'course, I could put a boost converter in first, then regulate what came out -- you'd lose efficiency in good light but gain it in low light.  A boost around 2.5 - 3x would let you use a cheapo regulator and get use out of those gloamy hours.

Or maybe I'll just stick one of these on a backpack, sashimono style:
   50W Telescopic Vertical Axis Wind Turbine Free Delivery : Wind Power : Maplin
8)
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #36 on: March 31, 2011, 12:56:27 am »
I'm still lusting after phased plasma rifles in the 40W range.

ftfy  8)

Well obviously, but not solar powered ones.  That would be ...disappointing.


Quote
So... it'd be fairly simple to rig a 5v regulator for a 6v panel with an LM2941 or its low-dropout ilk.  That makes a "USB-erizer" a matchbox dongle, easy to connect a USB charger too as long as it was useful at low voltages.  

 :thumbsup:


Quote
Hm.  Isn't there anything that just scrapes dribs and drabs of electrickery and pumps them in regardless?  Or am I confusing electrons and water again?

That'd be charging up an internal battery pack (or supercap or something) and then powering the USB gadget off the stored charge.  While you can scrape dribs and drabs into a known battery by various means, it's not as simple when you're trying to feed something that's expecting a regulated voltage source with defined current limits.


Actually, I quite like water analogies for electricity...  Voltage is height; current is flow; resistance is diameter of pipe; power is flow x change in height along a length of pipe; energy is amount of water x how high up your bucket is.  You can even do transistors as flap-operated sluice gates.  It all gets a bit Escher if you try to combine multiple transistors to make digital logic circuits, though.


Quote
Edit to add (after sucking on Ada's fount of boffinage): 'course, I could put a boost converter in first, then regulate what came out -- you'd lose efficiency in good light but gain it in low light.  A boost around 2.5 - 3x would let you use a cheapo regulator and get use out of those gloamy hours.

So you add a voltage-controlled switch (relay, FET, whatever - preferably something that doesn't need too much current) to bypass the boost converter when the panel output's above the 6.5V or whatever minimum the regulator needs.  Best of both worlds.
Careful, Kim. Your sarcasm's showing...

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #37 on: March 31, 2011, 09:59:49 am »
Well obviously, but not solar powered ones.  That would be ...disappointing.
You get one shot, then rack it on a ziggurat-topped altar in the mountain sun to charge for generations.  It's probably why the Mayan calendar has such long cycles.
Quote
So you add a voltage-controlled switch (relay, FET, whatever - preferably something that doesn't need too much current) to bypass the boost converter when the panel output's above the 6.5V or whatever minimum the regulator needs.  Best of both worlds.
And you'd end up with a reliable 5v with highly variable current across a wide range of lighting conditions.  We know that a phone won't charge from that, but what about a bogstandard USB battery charger like the doughty Eneloop?

What we need is a bench and a variable power supply and probes.  Or moar googles.   :thumbsup:
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Re: Solar gadgets + AA's
« Reply #38 on: March 31, 2011, 11:12:40 am »
whilst you boffins discuss mountain top altars and the amount of sun /moonshine thereon ...

what's the collected wisdom of the forum on charging AAs from a 6V 3W dynohub? 
Evidently one needs to convert AC to DC with something like an E-Werk or a Pedalpower+ Universal cable  - or is there something lower cost?   and  any suitable chargers to run directly off it without running through a Li-poly ?

I don't mind plugging stuff together but soldering voltage regulators and diodes & stuff is beyond me, except with absolutely crystal clear step-by-step illustrated instructions .

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #39 on: March 31, 2011, 01:24:29 pm »
what's the collected wisdom of the forum on charging AAs from a 6V 3W dynohub?

B&M Ixon IQ + ride & charge cable.  You get a pretty good bike light thrown in.

One of the multitude of dynamo-USB supplies combined with a ubiquitous USB powered battery charger.

Connecting the batteries (in series, which is only sensible if they're all at the same level of charge) directly to the dynamo via a bridge rectifier - works surprisingly well, as the dynamo supply is effectively a constant-current source, and 500mA is a reasonably AA/AAA-friendly charging rate.  The gotcha is that there's no charge monitoring, so once they're full they'll start to get hot, which isn't good for the long-term health of the batteries.
Careful, Kim. Your sarcasm's showing...

Re: Solar gadgets + AA's
« Reply #40 on: March 31, 2011, 03:03:53 pm »
what's the collected wisdom of the forum on charging AAs from a 6V 3W dynohub?

One of the multitude of dynamo-USB supplies combined with a ubiquitous USB powered battery charger.



I'm a newbie at all of this... and on a budget.  Can you point us in the right directions amongst these ubiquitous multitudes ?
I conversed with the folks at Pedalpower about this and they were talking about taking 11 hours to charge 2 x 1000mAh AAA unless using one of they Li-Poly batteries, which adds a level of complexity and cost I am keen to avoid.

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #41 on: March 31, 2011, 03:16:19 pm »
...and therein lies the "just buy some Duracells from the garage" rub, methinks.
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #42 on: March 31, 2011, 03:22:47 pm »
I'm a newbie at all of this... and on a budget.  Can you point us in the right directions amongst these ubiquitous multitudes ?

Something like the Dahon Reecharge or B&M E-Werk.  On a budget they aren't, though.  There are designs for homebrew equivalents on the web, of varying levels of cleverness (read: efficiency), which will work out a lot cheaper, but require a bit of electronics-fu.

USB battery chargers are much easier to come by.  You can probably find them in your local supermarket.  The problem with those is that they tend to be limited to charging a pair of cells in series at fairly conservative rates.

One of the better options I've found is the SCH600F charger.  It has 4 independent charging channels, and will run on USB-spec power.  It's a bit cheap and plasticy, and there's a big 'refresh' button that will need to be molly-guarded or disconnected internally to avoid accidental discharge, but it appears to work.


Quote
I conversed with the folks at Pedalpower about this and they were talking about taking 11 hours to charge 2 x 1000mAh AAA unless using one of they Li-Poly batteries, which adds a level of complexity and cost I am keen to avoid.

That seems awfully conservative, or awfully inefficient.  I'm not sure which.


The problem is, there aren't any really nice solutions to this, and the commercial products are inherently niche and therefore expensive.  That's a large part of the reason I'm designing my own: it'll still be hideously expensive, but at least it'll do what I want it to do.
Careful, Kim. Your sarcasm's showing...

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #43 on: March 31, 2011, 03:29:04 pm »
...and therein lies the "just buy some Duracells from the garage" rub, methinks.

Quite.  If it's literally just standard AA/AAAs you're worried about, rather than smartphones or Garmin Edges or netbooks or similar, then you really have to be very off the grid before carrying a few sets of spares isn't by far the simplest solution.

If you're set up to charge USB-powered gadgets, then carrying a charger to do AAs as well isn't unreasonable, but otherwise I think your best low-budget options are a dumb rectifier circuit and a Mk1 finger to detect when the charge is complete (and live with the shortened life expectancy for the NiMHs) or buying/carrying spares.   :-\
Careful, Kim. Your sarcasm's showing...

andygates

  • Peroxide Viking
Re: Solar gadgets + AA's
« Reply #44 on: March 31, 2011, 04:35:31 pm »
What I'm keen to have is the option of going off-grid for a while, very specifically for this LEJOG but also for non-bike stuff like kayak camping (romantic notions of Forrest Gump "just keep pedallin'" notwithstanding). 

Charlotte's just hooked me up with her magic charger, which covers all the battery angst. 

I'm pretty much sold on Ada's tough 2w panel.

And I think this might be the solar-to-USB boost-and-rectifier in one that I'm after: Single-Stage 5V USB Voltage Regulator.  See also here and a nice clear circuit here
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.

Re: Solar gadgets + AA's
« Reply #45 on: March 31, 2011, 05:28:59 pm »
...and therein lies the "just buy some Duracells from the garage" rub, methinks.

Quite.  If it's literally just standard AA/AAAs you're worried about, rather than smartphones or Garmin Edges or netbooks or similar, then you really have to be very off the grid before carrying a few sets of spares isn't by far the simplest solution.


Thing is I could get through an awful lot of AAs.    There's 2 in the Garmin, 3 in the head torch - all of which need to be replaced probably once in every 24 hours, and another 4 in the Hope Vision 1 (which would become my back-up light when I get a dyno powered front light) - possibly replaced twice in 24 hours.    Say a pack of 12 every 24 hours.   On a 600 that's either a lot of weight or a lot of cost buying duracells at garage prices, when I could be using the dyno to be charging spares sequentially during daylight hours.... not to mention the environmental impact, cos I'm probably not going hunting for a recycling facility when I'm in the middle of an audax.

At the moment phone charging is not an issue because I've an old fashioned non-smart phone with a battery that can go nearly a week.....  

Sorry to be a pest, but can you point me towards a suitable site for "Building Dumb Rectifiers for Dummies" ?   I literally have no clue what to look for.

Re: Solar gadgets + AA's
« Reply #46 on: March 31, 2011, 06:47:04 pm »
does this make sense for example....

http://i143.photobucket.com/albums/r154/n4zou/lights/DynamoUSB-2.jpg

My reading suggests the designer was using the impedance of the batteries to regulate the current to the USB rather than as a battery charger per se..., but battery charging a side benefit....  If I arranged the 4 NiMH in a battery case that's compatible with the Hope - maybe the one with PP3 connectors ?   


or this
DIY hub dynamo usb charger &raquo;  arenddeboer.com
and plug the SCH600F charger into it ?


Re: Solar gadgets + AA's
« Reply #47 on: March 31, 2011, 07:11:02 pm »
...and therein lies the "just buy some Duracells from the garage" rub, methinks.
The trouble with Duracells from the garage is that they often perform poorly in modern equipment. They don't like to give a high current, and the voltage drops below that of 1.2V rechargeables before they are half used, provoking "batteries low" turn-offs.
If you want disposables, lithium are best, but they aren't so common (supermarkets are usually the best place)  and are fairly expensive. They are very light though.

Kim

  • Timelord
Re: Solar gadgets + AA's
« Reply #48 on: March 31, 2011, 08:21:26 pm »
does this make sense for example....

http://i143.photobucket.com/albums/r154/n4zou/lights/DynamoUSB-2.jpg

My reading suggests the designer was using the impedance of the batteries to regulate the current to the USB rather than as a battery charger per se..., but battery charging a side benefit....  If I arranged the 4 NiMH in a battery case that's compatible with the Hope - maybe the one with PP3 connectors ?

Ach, I wouldn't plug my shiny smartphone into that.  That 6V nominal battery voltage is way outside USB spec.

As a circuit for charging batteries it'll work fine though.  They'll just start to cook (but relatively slowly, as it's not all that much power) when they're full.



Quote
or this
DIY hub dynamo usb charger &raquo;  arenddeboer.com
and plug the SCH600F charger into it ?

Danger, lack of over-voltage protection!  That'll work, but Magic Smoke is liable to escape when going Very Fast without much of an electrical load.  The dynamo will easily exceed the 26V maximum rating of the LM2940 under those conditions.

The simple solution is to add a pair of zener diodes, of say 20V rating, back-to-back across the dynamo input.  Then the rectifier will never see more than 20V and the excess power will be dissipated as heat in the zeners.  The problem then becomes one of getting rid of the heat - I've found that they either fail from overheating (zener diodes, thankfully, tend to fail short-circuit), or cook the surrounding circuit board to a brittle crisp.  You're also wasting energy heating up diodes that would presumably better be used cycling along.

There isn't a simple solution to this one.  I'm still testing a fairly complex one.   :-\
Careful, Kim. Your sarcasm's showing...

andygates

  • Peroxide Viking
It takes blood and guts to be this cool but I'm still just a cliché.
OpenStreetMap UK & IRL Streetmap & Topo: ravenfamily.org/andyg/maps updates weekly.