From: muratlanne@gmail.com   
      
   "Jim Wilkins"  wrote in message news:roc0gj$alc$1@dont-email.me...   
      
      
      
   "Bob F"  wrote in message news:robrpv$qlk$1@dont-email.me..   
   ...   
   I would like to assemble these into a backup supply for a couple desktop   
   computers and associated equipment in case of power outages...   
   =====================================================   
      
   "The cheapest way to charge a nickel cadmium battery is to charge at C/10   
   (10% of the rated capacity per hour) for 16 hours.   
      
   ==============================   
      
   The equivalent slow-but-sure charging method for lead-acids is to limit the   
   charging voltage to the "float" level, which is just below where the battery   
   begins to gas, typically around 13.6V.  The UPSs I've checked do this, and   
   it's a selectable option for my solar charging controllers. The disadvantage   
   is slow charging time after the battery reaches around 80% of its Amp-hour   
   capacity, because the battery draws less and less current at that voltage as   
   it approaches full charge.   
      
   Initially my UPS charges a heavily discharged battery at 6 Amps and the   
   battery's state of charge determines the voltage. When the voltage reaches   
   13.6V it stops increasing and soon the current begins to decrease gradually,   
   taking several/many hours to stabilize at or below 1% of the battery's   
   Amp-hour rating, C, for instance 180mA for a 12V 18A-H AGM.   
      
   That's what to expect from the battery charger built into a UPS, though you   
   should check it yourself as the settings are different for gel, agm and   
   flooded batteries. A UPS with swollen batteries may be available cheaply or   
   free if you look around. Good cheap used DC-AC inverters to build your own   
   UPS are much rarer.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)