[CentOS] Back to apcupsd

John R Pierce pierce at hogranch.com
Wed Mar 3 01:06:50 UTC 2010

m.roth at 5-cent.us wrote:
> ...that while the nominal voltage for the APC
> SmartUPS 3000 is 48V, the new batteries are showing 55.4V. 

lead acid batteries are 2.1-2.15V per cell when fully charged, and the 
trickle charging float voltage is more like 2.3V per cell.  2.3 * 6 
cells/battery * 4 batteries == 55 V

to read the batteries charge state, you would need to disconnect them 
from the charger(UPS) for about 4-6 hours before reading the voltage, 
this lets the surface charge dissipate.   After doing this, you should 
see 12.6-12.8V per 12v battery, or 50.4 to 51.2V for your stack of 4 * 
12V.  All these voltages assume 68-72F battery temperature.    48V is 
nearly totally discharged

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