"Tom Biasi" <tombiasi***@[EMAIL PROTECTED]
> wrote in
news:K7qdnTlMrY6hN__VnZ2dnUVZ_qPinZ2d@[EMAIL PROTECTED]
>
> "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
>
I didn't know what they were at that point, but I've learned a little more
since then ;) I've been concentrating on Maxim, mostly because they have
a
lot of really good Application Notes, also because I think I can get all
the major items from there. "Charge regulator" is a new/different phrase
for me, tho', so I'm searching on it, and checking into that the Maxim
site
lists under that term.
What gets confusing is that there often seem to be several possible units,
or combinations of units, that perform similar functions, so I've been
trying to differentiate them and find which would be best. I did find a
couple of Charge Regulators, too.
What surprises me is that the ICs seem to be quite inexpensive - most of
the units I'm looking at are under $2 each. I still would have to add up
the associated resistors, inductors, and whatnot, but I *think* I can keep
it under $20...
I guess the next step is for me to collect the datasheet titles/locations,
find one or two solar cells (and configurations thereof) that seem like
they'd do the job, and then write to Maxim and ask how it all should go
together - although the schematics for the individual applications
actually
make some sense to me, the problem is that I don't know whether I can
just,
so to speak, "paste the two diagrams together" and then stick in teh solar
cell(s) and diode, or whetehr there is somethign special that needs to be
done so as to make something that both works, and is safe ;) They were
good about answering the first question I sent them, so I'm hoping they
can
give me a clue about me****ng the various application notes. If there will
be a charge control IC, I'm assuming that I don't have to worry too much
about an "overpowered" solar-cell input...
ANyway, thanks for all the info (and patience ;) ) over the past couple of
weeks; I've learned a lot and think I might actually be able to get this
project going!
- Kris
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