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
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