Vic, Thanks for adding that - in my haste, I forgot to say that indeed for a Smartcharger, the current must be set with consideration for the battery. OTOH, I believe the thing that is usually adjusted is the 'bulk current' which is the high current part of the 3 stage charging cycle.
Reviewing the UC3906 3 stage controller chip, I found that Stage 1 was the bulk current stage - where the resistance can be changed to limit the maximum current. When the terminal voltage reaches 95% (13.7v) of the full charge voltage, stage 2 is triggered which increases the voltage (to 14.4 volts for a 12 volt SLA), and the charging continues until the current drops to a small value - then stage 3 begins which limits the voltage to 13.8 volts (trickle charge value). 73, Don W3FPR > -----Original Message----- > > W3FPR - Don Wilhelm wrote: > > > Of course, an even better system is to use a 3 stage charge controller > > specifically designed for SLA batteries - something like the A & A > > Smartcharger would do a fantastic job. > > Keep in mind that the Smartcharger (and most likely other 3-stage > chargers) has an adjustment for the amount of trickle current. If the > charger is designed for an automobile battery this will be too much for > a small gel cell and will destroy it. > > How do I know? Because I have a Smartcharger and I made an error in > arithmetic when I selected the value of the resistor that controls the > trickle current, and the rest -- including my 4ah gel cell -- was history. > > -- > 73, > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco > -- > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.10.18/91 - Release Date: 9/6/2005 _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
