Kris Krieger wrote:
> ehsjr <e.h.s.j.r.removethespampunctuation@[EMAIL PROTECTED]
> wrote in
> news:u3E8k.54$WJ.12@[EMAIL PROTECTED]
>
>
>>Kris Krieger wrote:
>>
>>>Peter Bennett <peterbb@[EMAIL PROTECTED]
> wrote in
>>>news:kea3641d48c8bkakmddm6t3s8ghlljgg4n@[EMAIL PROTECTED]
>>>
>>>
>>>
>>>>On Mon, 23 Jun 2008 22:46:24 -0500, Kris Krieger <me@[EMAIL PROTECTED]
>
>>>>wrote:
>>>>
>>>>
>>>>
>>>>>"Tom Biasi" <tombiasi***@[EMAIL PROTECTED]
> wrote in
>>>>>news:SN6dnboY57y6pf3VnZ2dnUVZ_gCdnZ2d@[EMAIL PROTECTED]
>>>>>
>>>>>
>>>>>
>>>>>>May I suggest deep cycle sealed lead acid.
>>>>>>
>>>>>>Tom
>>>>>>
>>>>>
>>>>>My main question is, are they easily replaceable? THey do seem to
>>>>>be easier to deal with, but these units are going into things that
>>>>>I'll (hopefully!) be selling, so I need to make it all as easy as
>>>>>possible, and I know that people can buy the NiMH batteries pretty
>>>>>easily. That's the only reason I've sort-of "fixated" on them.
>>>>>THat, and it's easy to get the mA ratings that will drive the LEDs I
>>>>>want to use (found one that uses 20 mA, and 3.4V average, but gives
>>>>>out an amazing (to me) average of 18,000micro-candela, which is 226
>>>>>lumens, which is a bit more than is given off by a 20-watt
>>>>>incandescent bulb (220 lumens). With the LED driver (I think it was
>>>>>you who'd recommended those), that should work out well and I could,
>>>>>I think, use two such LEDs, which should be about the lumens
>>>>>produced bya 40 watt incandescent bulb - which would be super!
>>>>>
>>>>>Anyway, I haven't seen any drivers that I can recall reference
>>>>>running off of anything other than NiCad, NiMH, or Lithium-Ion
>>>>>batteries,so my impression was that those are the only two that have
>>>>>both enough voltage, and generate enough current, to run the
>>>>>drivers. I've also used store- bought solar lights, which had
>>>>>either NiCad or NiMH (depending upon th etype), so I know those will
>>>>>work when left outdoors.
>>>>>
>>>>>So, it might very well be that rechargeable lead-acid bnatteries can
>>>>>perform similarly, it's just that I don't know anything about
>>>>>them...
>>>>>
>>>>>- Kris
>>>>>
>>>>
>>>>Lead-acid batteries are normally large and heavy. Your car battery
>>>>is lead-acid, for example (although there are smaller sizes, and some
>>>>variations that don't have a liquid electrolyte, available). If you
>>>>are considering AA, C or D cells for your project, lead-acid
>>>>batteries are almost certainly not a consideration. I'm not aware of
>>>>any lead-acid batteries in a "dry cell" format.
>>>>
>>>
>>>
>>>AA only.
>>>
>>>The background, in brief:
>>>
>>> These will be fairly small-scale units that I can put inside
>>> of
>>> stained-glass things ("lanterns", so to speak) that I design and
>>> hand-craft, my intent being to sell them. So the batteries
>>> will be just the normal NiMH things that pop into regular
>>> ol' solar garden/accent lights. Since the betteries will
>>> eventually need to be replaced, I'd like them to be things
>>> that people can find very easily and that don't cost an arm
>>> and a leg. Someone (Tom B.?) had recommended an LED driver,
>>> and I've been looking around at otehrs as well (mainly to
>>> read teh application notes and datasheets and whatnot so as
>>> to gain a better understanding), and Maxim posted a
>>> nifty diagram for a combination current and voltage amplifier
>>> plus an LED driver (in case it'd be helpful to anyone else,
>>> the URL is:
>>> http://www.maxim-ic.com/appnotes.cfm/appnote_number/3871
)
>>> and I *think* that, for the input, I can use the output form
>>> a
>>> combination battery+solar-cell charging+battery management
>>> circuit.
>>>
>>> I know that I can build a super-simple unit that will drive
>>> one
>>> normal-brightness LED; I found a few different schematics for
>>> simple low-brightness units, and the simplest are little
>>> more tahn a solar cell, diode, battery, resistor, and LED,
>>> with no sort of overcharge protection or any other
>>> accomidation for any special needs that one or another sort
>>> of battery might have. THey're robust, but they won't work
>>> for me because these things will be lighting stained
>>> glass, and even clear textured glass doesn't transmit as much
>>> light as does a smooth clear enclosure (I think the
>>> commercial ones are acrylic). Also, the potential customers
>>> and sales venues I've polled all have the same complaint:
>>> commercial solar lights are too dim. Ultra-cheap is not
>>> part of my equation here - I am most definitely not going
>>> seeking to try to compete with the "$5-$9 light" market;
>>> Wal-Mart has that very well-covered. Rather, the units,
>>> being handcrafted stained glass, will each be a minimum of
>>> around $60, and prob. a lot more than that, depending upon the
>>> time and skill it takes to construct a particular design. I
>>> do want to squeeze as many Lumens as possible out of a
>>> *maximum* of 4 NiMH batteries, to be charged during the
>>> daytime by solar cells, plus I want to charge the batteries
>>> in about 5-6 hours in good sunlight - and that last part is
>>> why I'm looking into overcharge protection, since it's
>>> likely that some lights will receive 8 (or even mroe)
>>> hours of good sunlight.
>>>
>>>So that is why I'd asked about whether thre is any significance to
>>>the relation****p between the solar cell(s) V/mA rating, and the
>>>battery V/mA rating - I don't want to "cook" the batteries.
>>>
>>>TIA!
>>>
>>>- Kris
>>>
>>>
>>>
>>>
>>
>>I think you've gone down a path that may be counter productive.
>>First: The amount of power you will get from the solar panel
>>will depend predominantly on how much surface area you can get
>>exposed to the sun. You can include instructions to the
>>consumer concerning installation for maximum exposure, but
>>the only factor _you_ can control is the surface area.
>>
>>What does that mean at this point? You know the size of what
>>you are building, so _you_ need to find solar cells that
>>will fit that area. *That* selection will dictate how much
>>power the design will have available, and it will be a range
>>from minimum (0 on a cloudy day) to maximum. The amount of
>>power available from the panel will vary throughout the day.
>>
>>Only when you know how much power will be available in a
>>typical *week* can you properly design the electronics.
>>
>>So, post again once you have found a solar panel (or
>>combination of panels) that will fit the device you are
>>making. How much power will be available to work with
>>under the "typical" conditions of your intended market?
>>
>>You want something simple and better than a typical solar
>>powered garden light. So do I - and I also want cheap
>>oil. Neither is generally available these days. You
>>can maximize what a typical solar powered garden light
>>(like cat# SPL-09 at http://www.allelectronics.com/
see
>>also cat# SPL-05) produces with increased complexity and
>>construction cost. If you can live with the performance
>>level of either of those, you job is done - just incor****ate
>>their panels & circuitry in your prroduct. Oterwise, you
>>have to put in the work to search for the best panels
>>you can get to fit your product, and obtain the best
>>performance possible from that power source.
>>
>>Without knowing how much power is available, it is impossible
>>to say how long it will take to charge a cell, nor can the
>>charging circuit be designed for best performance.
>>
>>IIRC, no one has told you to do that work - identifying
>>the panels - in the various threads, posts and replies since
>>you started looking for an answer. Of course, I may have
>>missed it, so if you have identified the panels, how much
>>charging power is available to work with?
>>
>>Ed
>>
>
>
> Actually, the initial consideration was finding how much brightness
would
> be enough, and which LEDs (and/or combination thereof) will provide it.
> From there, it goes backwards to find out how to run them off of a
> *maximum* of four 1.2V NiMH batteries. From there, working backwards
> again, is the charge controller IC - finding the one that will charge,
> and keep from overcharging, 3 to 4 of the batteries. THe solar cells
> (not panels, just cells) is actually the last thing. WHat I'm trying to
> figure out is whether I should have the solar cells producing the same
> total voltage as that which the batteries will have (3.6V for three of
> them, 4.8V for 4); since I've learned that NiMH are supposed to be fast-
> charged rather than trickle-charged, I'm tryign to figure whether solar
> cell amperage is more im****tant for doing that, with voltage being
> insignificant, or what.
>
> Only *after* I know all that, can I select the specific cells, and
> configuration therof...
>
> - Kris
As you said, you are working backwards. You don't yet understand
that doing it that way can result in a specification for cells
that are "unobtanium".
Ed
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