maybe, it's not the simplest thing to integrate this within the pic. i
once did it in a very simpel way, but i think there are better ways...

it depends on what type of backup battery you have. if it's nicd or
nimh, look at maxim chips (www.maxim-ic.com) as far as i remember, these
are the max712/713 chips. if you have a lead acid battery, search at
texas instrument's web site (www.ti.com). unfortunately, i don't
remember the number, but there is a single chip lead acid charger with
integrated temperature sense, as environment temperature has to be
considered when chargin lead acid.

hope that helps!
tino

************************************************************************
******************************


>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>On Behalf Of Francois Robbertze
>Sent: Friday, May 06, 2005 10:19 AM
>To: Piclist@mit.edu
>Subject: [PIC] Backup Battery
>
>
>The archives and microchip lists intelligent battery chargers. 
> I need something simple and dont want to re envent the wheel, 
>blah, blah...
>
>The truth is that I know to little about batteries to even try 
>at this stage. 
>
>Can someone help me with a schematic and code to charge a 
>12Volt buckup battery?
>
>The buckup battery is for a system that must generate SMS 
>mesages via a GSM module even in the event of a power failure.
>
>The PIC must also generate a message when the battery needs 
>replacement.
>
>I am using a 16F628 but can go to other PIC if A/D is essential. 
>
>I see that the smart chargers measures the charge current, 
>battery temperature etc., but I dont know if the comparrators 
>might be enough. Start the charge whenm the battery ia below a 
>certain voltage(?) and to stop the charge when the battery 
>reaches a certain voltage(?)
>
>I also dont know if it is best to run the system from the 
>battery constantly or if I must switch to battery in the case 
>of a power failure
>
>Thanks
>
>Francois Robbertze
>
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