Re: Another Novice Q. - recharging - Volts and Amps

"Tom Biasi" <tombiasi***@optonline.net> wrote in
news:CrydnV3Ospmxm_3VnZ2dnUVZ_vninZ2d@xxxxxxxxxxxx:


"Kris Krieger" <me@xxxxxxxxxx> wrote in message
news:HN6dnUa5Bpt2esLVnZ2dnUVZ_h3inZ2d@xxxxxxxxxxxxxxxx
Apologies in advance if this is a dopey question, but, when it comes
to recharging batteries, and using a solar cell to do that, what I've
been assuming, based on th info that peopl ehere have kindly
provided, and also that I've foind on-line, is that teh mA output of
the solar cells should not exceed 2/10ths to maybe 3/10ths of the
battery's mA rating, and teh voltage produced by the solar cells
should be as close as possible to the total voltage of the battery or
batteries. But I wanted to check whether that assumption is correct,
becasue I think I'm getting closeto getting some parts and trying a
couple of assemblies.

Thanks In Advance!

- Kris

Hi Kris,
Different batteries need different charging conditions.
Look at the specs for your batteries.
The charging requirements will be discussed.
Some batteries may say: Charge at .1c for 10 Hrs.
This means to charge them at one tenth the AH rating for 10 Hours.
The VPC (volts per cell ) will also be specified.
For example: NiCads are about 1.2 VPC and can charge at about 1.3-1.5
VPC (follow manufacturers specs) at .1 -.3 c. (again, follow specs.).

Ah, OK, that at least gives me a ballpark figure - thanks :) !

(I do try looking all these things up via Google before posting
questions, but often, I don't know the terms that will get me the correct
*type* of answer - IOW, if I want info about charging, I don't want to
look at endless lists of people selling battery chargers, but the latter
is the sort ofthing I've been having to trudge through...so even just
getting the right terminology has been a huge help).

So if you have a 12 volts NiCad pack that would be a 10 cell NiCad
battery. If you are using lead acid cells, the numbers are different.
Keep in mind that photo cell manufactures inflate their specs by using
bright sunlight averages.

Tom



THe Max I'll use will be 4 1.2V NiMH batteries, for small lighting
units. What I'm trying to figure out is how to avoid "cooking" the
batteries ;) by putting in *too much* voltage, but I also want to take
into account the very thing that you mentioned, i.e. the "brightest
possible sunlight" rating for the cells.

I had bought some Malibu NiMH batteries at WalMart, but now i'm looking
at ordering something more along the lines of Energizers (for example,
http://www.rei.com/product/719570?cm_mmc=cse_froogle-_-datafeed-_-
product-_-na&mr:trackingCode=B42A264C-BE3F-DD11-98CA-001422107090
&mr:referralID=NA or these
http://www.circuitcity.com/ssm/Duracell-AA-Rechargeable-Batteries-4-Pack-
DC1500B4/sem/rpsm/oid/52666/catOid/0/rpem/ccd/productDetail.do) or one of
the other known/name brands, because just today I read some cautions
regarding "bargain" batteries.

I at least found some interesting LEDs at
http://www.optekinc.com/viewparts.aspx?categoryID=53 , some of them claim
to put out 18,000umc average using 20mA and typical "forward" voltage of
3.4, so that I can run off of a reasonable LED driver (considering some
Maxim items, or the "Micro-Puck").


ANyway, I'll look around and see whether ther eis info about recharging.
THis is good to know because, assuming I can do what i'm intending, and
call sell the units, I can also incoude costomer info as to the best
replacement batteries, should replacements be necessary.

Thanks again :)

- Kris


.

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