Sizing a power supply for ups.

Discussion in 'General Electronics Chat' started by mbohuntr, Dec 22, 2012.

  1. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
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    I was reading another post on sizing a battery for UPS, and have a question of my own. I am designing / building a security system for a outbuilding. It will have a 12v battery, and two voltage regulated circuits. (Detectors and MCU). I won't have the actual power consumption until it is up and running.
    I was looking at a battery charger/maintainer for the battery, but don't want the charger working overtime during normal standby operation Any information or advice would be greatly appreciated!
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Some battery chargers are specifically designed to "work overtime". For example, trickle chargers, are very low current chargers that take their time charging since there is no rush to finish the charging and lead acid batteries don't care how fast (to a limit) or slow they are charged. Also, UPS systems are usually used infrequently so charging time is not important. Lithium batteries last longer when charged at constant current Southey have different rules. In other words, a simple motorcycle trickle charger system will likely be fine for a wet lead acid battery, otherwise look to the battery manufacturer for advice on any other type of battery (lead gel, lithium, etc).
     
  3. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
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    So, as long as the float output of the charger is greater than the standby draw of the system, all is good? I'm guessing the standby mode of operation will draw somewhere around 250mA.
     
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