"Kris Krieger" <me@[EMAIL PROTECTED]
> wrote in message
news:Q-SdnWZbG9nt4f_VnZ2dnUVZ_r3inZ2d@[EMAIL PROTECTED]
> 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
>
>
>
>
After you explained that you would be using small batteries the lead acid
suggestion would not apply.
Yes there is a relation****p between the charger and the batteries, a
rather
im****tant one.
Since you indicated that you may use NiMH the relation****p is even more
serious.
You will not get reliable charging without some type of charge regulator.
I think when you first posted a while back someone mentioned that they are
available as commercial units for less than you can make one.
Tom
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