24 Volt Mini UPS Schematic need help

Discussion in 'General Electronics Chat' started by ShayanFiroozi, Nov 18, 2015.

  1. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    Hi friends ,

    i need help with 24 volt mini ups i designed which you can see in attachment

    i'm a computer network expert so i'm compeletly beginner on electronics

    any suggestion ?

    many thank !
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    The diodes are drawn backwards on the Negative supplies,
     
  3. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    it's a mini ups , feed the load with 24 volt battery when the main is not present , and charge battery when main come back
     
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    A simple mains 220V ac coil relay across the supply will detect power fail, with a set of dpdt contacts to switch off the battery from charge to output will do.
     
  5. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    sir , you think a design like that will work ?
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Yes, do you want to maintain a 24v supply without interupt when the mains fails,?
     
  7. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    Yes , and charge the battery when mains is available , any suggestion ? or any change should i have to make ?
     
  8. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Best to have the battery under charge constantly and take the load from the battery terminals so it keeps topped up, like in a car, then when the mains fails the battery supplies the load,

    you just need to monitor the low voltage on the battery to disconnect it from being discharged too low, an op amp comparator will do that.
     
  9. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    i couldn't find a good 24 volt low voltage disconnect circuit on internet,i don't wanna buy , is there any good circuit with relay ?
     
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