SLA battery charging with PWM but which frequency

[Heckler]

here are several BUT none of them use a PIC micro or PBP...


http://www.repeater-builder.com/backup-power/pdfs/automatic-sealed-bat-chrgr.pdf

http://adventure-radio.org/ars/pages...ext/N7CEE.html

http://www.batteryspace.com/leadacid...sfloating.aspx

http://www.theheathkitshop.com/page4/page4.html

[Charles Linquis]

I haven't taken the time to read the whole thread, but you certainly CAN have varying NOT CHOPPED voltage (and constant current, too, if you have a current sensor in the path) with PWM. You simply have to make a 'buck' converter. You can find a schematic at

http://dl.dropbox.com/u/566712/PIC_BUCK.jpg

To be accurate, the circuit does require a small minimum load. You also have to measure the output voltage with an A/D channel and change the PWM value accordingly, but the output is a low-ripple DC voltage at up to 6 Amps.