I believe that we may be making battery charging too difficult. Heat is the single worst cause of battery failure and poor performance. To minimize the heat on charge build up (for any battery), pause charging is the most effective way to make a simple charger. Ni cells can all be easily charged with constant current with an LM317, terminate at peak voltage. Both SLA and Li can be charged to their respective fixed voltages, and still be safely pulse charged to provide 87-93% nameplate capacity. Steve Halla ----- Original Message ----- From: "Buehler, Martin" To: "Microcontroller discussion list - Public." Sent: Tuesday, May 10, 2005 3:21 AM Subject: RE: [PIC] Backup Battery > 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 >> >>-- >>http://www.piclist.com PIC/SX FAQ & list archive >>View/change your membership options at >>http://mailman.mit.edu/mailman/listinfo/piclist >> > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist