"Kris Krieger" <me@[EMAIL PROTECTED]
> wrote in message
news:kOGdnVPS95_Nuf7VnZ2dnUVZ_hSdnZ2d@[EMAIL PROTECTED]
> 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
Kris,
It would be wise to consider solar panel size at this point rather than
last, if only for reality check.
Solar lights usually are very dim. That is primarily because the size of
the solar panels and the amount of power they can produce during sun****ne.
The batteries only have to be as "large" as the power produced. The best
solar lights I have seen have 8" x 12" panels which are not mounted to the
light itself (this also helps in that the lights themselves can be placed
in
shady areas).
Scott
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