Reduce 50 Amps

Discussion in 'General Electronics Chat' started by salytwo, May 21, 2015.

  1. salytwo

    Thread Starter New Member

    May 21, 2015

    I am going to run 5 wireless boards (Ubiquity Nano Station M2, 24v, 1A) using 2 batteries of 12v/50a to obtain at least 9 hours.
    but I am afraid of much amperage can damage these device because every wireless device need only 24v/1A.

    so can I reduce the 50 Amps to 1A ?

    whats your recommendations ?

    Best Regards
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    The wireless modules will only draw the current they require, not 50Amps
  3. cornishlad


    Jul 31, 2013
    I think you are confused about the battery rating. The 50A you quote maybe 50amp/hours which is simply a measure of their storage capacity. two 50A/H batteries in series gives you a 24 volt 50A/H battery. It doesn't mean that any load connected to it will take 50 amps. Each 24 volt load (a wireless board) will take only the current it requires.
    Five boards will draw 5 amps. The 50A/hour rating will tell you how long the battery will hold up. If they are lead acid batteries and you allow them to discharge to about 24.2 volts they will last 10 hours but will be completely flat.
    It's not generally recommended to discharge ordinary LA batteries to below about 50% so about 5 hours of operation in that case.

    I recommend a fuse (say 10 amps in this case) LA batteries can burn wires faster than you can blink if a short circuit should arise.
  4. salytwo

    Thread Starter New Member

    May 21, 2015
    Dear cornishlad,

    You are absolutely right. but connecting 50A/H to devices that consume 1A will not cause damage to the circuit ?
    Are you sure ?

    One friend tell me he tried to run ADSL modem (12/0.8A ) on car battery but the high amperage cause damage to the circuit after a couple of hours. damage in diods.

    Thank you a lot for ur kind help...
  5. RamaD

    Active Member

    Dec 4, 2009
    50A-hr battery will not pump 50A current, and the current is determined by the device.
    Your friend's ADSL modem likely requires AC, (mine does) and is rectified inside with a diode bridge. In such a case, 2 of the 4 diodes are conducting half the time, and the other two in the remaining half. If this is connected a DC source, like a battery, only 2 diodes are conducting all the time; and the other 2 diodes sitting pretty cool doing nothing. This could have caused the diodes to blow.
  6. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    If connection to the car battery was the cause of the modem failure, it was because the battery voltage was too high at >13.5V. If there were over-voltage protection in the form of a 14V zener diode, for example, it would have slowly cooked.
    Last edited: May 21, 2015