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Multiple Input Charger Help

Discussion in 'General Electronics Discussion' started by ScottPicsolve, Jul 25, 2014.

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  1. ScottPicsolve

    ScottPicsolve

    2
    0
    Jul 25, 2014
    Hey Guys,

    I have a quick question about a power supply hookup I am currently doing. Basically I have a 24VDC to 5VDC converter which has two 24VDC sources connecting to 1 input. The converter charges a battery and is located on a vehicle that docks every 2 minutes. The charging sources will never be running at the same time. Source 1 is a plug that is plugged in for over night charging and Source 2 has open contacts so that every time the car is docked, the battery charges. The problem I face is that if source1 is plugged in, the pins from the second source become charged. It may be possible for someone working on the car at night to accidentally short the contacts on Source 2. I need a way to keep the voltage to only the source that is currently being used for charging.

    I know I can put a diode on the incoming power wire, but I am not sure if this will give me a complete open circuit for source 2 or if i will still get some voltage back across the diode. I have contemplated building a simple switching circuit which opens the contacts on the opposite source when one source is plugged in but I'm in a time crunch and limited on space in the box which the converter is located.

    Here is a very crude drawing of the setup:
    Charge Circuit.png
    If I can get away with just putting diodes then that's the route i'm going to take. Just need a second opinion.

    Any help is greatly appreciated!
     
    Last edited: Jul 25, 2014
  2. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    A re-setable fuse like a PTC is the easiest option because you still need to charge the car so diodes wont work.
    Thanks
    Adam
     
  3. Canobi

    Canobi

    87
    3
    Jul 25, 2014
    How about a changeover reed switch?


    I have been working on a similar problem recently.
     
  4. ScottPicsolve

    ScottPicsolve

    2
    0
    Jul 25, 2014
    Hey Guys thanks for the replies!

    Arouse1973, why would the diodes not work?

    A changeover reed switch is a great idea i forgot about those. The only problem I see is the cost. I have 21 trains so its going to get a little expensive. Great answer though, it would do exactly what I'm looking for.
     
  5. Canobi

    Canobi

    87
    3
    Jul 25, 2014
    Yeh, they are a little pricey arent they, forgot that when I posted.

    It might be possible to cobble a pseudo changeover using a standard reed and relay maybe.
     
  6. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    I assume you meant in series, diodes only conduct one way. maybe I am not understanding where you are going to put them. Can you draw a circuit?
    Adam
     
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