In a message dated 12/12/04 00:35:05 GMT Standard Time, [EMAIL PROTECTED] writes:
When the battery is exactly at 13.8 volts, there would be no current. In practice found over the many systems worked on professionally this is not entirely correct. After the charging system comes out of the absorptive charge phase where the voltage has been allowed to rise above the normal bulk charge voltage for a limited time and now reverts to the float voltage, the battery indeed does not take any charge. It can even supplement the supply voltage and current for a short while after the main charge cycle. However if one monitors the battery over a longer period after the float charge period has started the battery will start to take a small charge that eventually settles on the 25 to 50 mA region for small SLA's. It all depends on the float voltage and the size of the SLA, but with a float voltage of 13.8V and a 12V SLA does definitely occur. Security and fire alarm technicians when carring out routine maintenance can note the current taken by SLA's in the alarm panels under float conditions as this can give an early indication of the forthcoming failure of the SLA. For critical systems under a maintenance contract they sometimes replace the SLA's at 2 to 3 year intervals to ensure system reliability under all conditions. A good source of SLA's that still have a useful life left in them if you can make contact with one of the technicians and I did! Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
