200A - Battery Charger Protection

Discussion in 'Power Electronics' started by rennie1080, Jul 13, 2018.

  1. rennie1080

    Thread Starter Member

    Apr 10, 2017
    40
    0
    I will set up a system that includes one main power ( 24 Vdc ) and back up battery( 12Vx2 ) . Main line ( 220 Vac go through ac/dc converter and 24 Vdc that we use ) and back up line ( 220 Vac go through 2x( 12V 120Ah battery and battery charger) ). I add diode in front of battery to protect them from inrush current ( approx. 200A, system normally draws 30-40 A ). But I find one diode to use in my country because of limited time. I dont know it could be use for that purpose. Or you can give another ideas for reverse current protection?



    [​IMG]
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    7,588
    1,254
    Last edited: Jul 13, 2018
  3. rennie1080

    Thread Starter Member

    Apr 10, 2017
    40
    0
    If I choose proper diode, why doesnt it effect against inrush current ? How can I adapt ntc into my system ? I attached the system design. I am open for your advice.
     
  4. rennie1080

    Thread Starter Member

    Apr 10, 2017
    40
    0
    Actually my reason that diode is used is to protect batteries not only inrush current but also reverse current .How does NTC thermistor prevent reverse current ?
     
  5. rennie1080

    Thread Starter Member

    Apr 10, 2017
    40
    0
    Any idea ?
     
  6. MisterBill2

    Well-Known Member

    Jan 23, 2018
    1,558
    276
    An NTC device is not intended to prevent reverse current. You have two separate requirements and so you will need two separate devices. But I will offer a suggestion, which is that you have described a very high power system capable of delivering huge amounts of power to a short circuit, and doing a lot of damage. And a motor that draws 200 amps starting current will need controls that are not simple or trivial. The project can cause a lot of damage if any errors are made.
     
  7. rennie1080

    Thread Starter Member

    Apr 10, 2017
    40
    0
    Is the system attached Ok ? Could you check it ?
     
  8. MisterBill2

    Well-Known Member

    Jan 23, 2018
    1,558
    276
    What is shown is a basic block diagram, not close to an actual circuit. While the concept is OK there no indication of an actual circuit, thus no means of providing any evaluation of the actual implementation. There are two undefined blocks, the upper with three connections entering, the bottom one with two entering, and tied to an "engine cutoff." No mention is made in the post as to what the engine is doing for the system. I would guess that the engine drives a generator or alternator to charge the battery, but that is only a guess, based on no expressed information.
    It may be your intention to have an engine driven 200 amp alternator charge the battery and power the AC output power converter, with the 20 amp battery charger as the normal means of charging the battery when AC power is available. That would be a reasonable arrangement, but at this point it is entirely a guess on my part.
    I can evaluate an actual circuit, and probably even design a system, but so far the best I can offer is a string of guesses.
     
  9. Tadiwanashe

    New Member

    Jul 20, 2018
    1
    0
    Hi Guy's i am scared of using ac direct to my rectifier and even my primary cool as this is because of short circuiting
     
  10. MisterBill2

    Well-Known Member

    Jan 23, 2018
    1,558
    276
    AC direct to rectifiers is done all the time, but certainly there are precautions needed. First, the rectifiers must have both voltage ratings and current ratings correct for the application. Next, or maybe first, the entire system must be designed for the application. That means that the application must be well understood. So the challenge begins with needing to know what the goal is: What is the system supposed to do? Not only the general description, but then also the details with numbers, volts, amps, watts. and time. Thiswill be quite complicated if those things are not defined. So thinking comes first.
     
Loading...