High voltage cutout for solar charger

Discussion in 'The Projects Forum' started by davebda, Apr 6, 2008.

  1. davebda

    Thread Starter New Member

    Apr 6, 2008
    Hello, I am another newbie hoping for help with a problem. I am the manager of a wildlife habitat restoration company. Our operation site is in the boonies of northern California which is a 7 hour drive from where I live.

    I purchased a solar panel powered battery charging system to keep our camp batteries constantly charged without using gas powered generators. The charging system consists of 3 15 watt solar panels and a charger. The panels connect to the charger and then the charger has a set of aligator clips that connect to the battery. The panels each put out 22 vdc. The charger regulates the voltage and charges the battery. It is a pretty good charger.

    My problem is that it is too good of a charger. It gets the battery up to 14.5 vdc, even when I have a bank of batteries set up. The system does not really have an adequate overcharge circuit. When the battery reaches 14.5 vdc, the charger cuts out for about 15 seconds and then cuts back in. During that 15 seconds a high pitched beeper sounds. And it just continues this cycle, on, off, on,..... The instructions instruct you to disconnect the panels and then turn something on to discharge the battery.

    I need the system to be self governing because I am only up there a couple weekends a month. Even when we are there, most of the time we are out in the field working on the project and not in camp. I would like to find a circuit that would monitor the voltage and at a set high voltage open up the connection between the panels and the charger. And then close the circuit when the battery goes below a set low voltage.

    It seems like I should be able to use some type of relay circuit that opens and closes at predetermined voltage levels.

    I am hoping one of you wizards can give me some guidance on either where I can purchase such a circuit or how to design one.

    Thanks in advance for your time.
  2. mik3

    Senior Member

    Feb 4, 2008
    you can use the op-amp to sense the voltage compared to a reference voltage and a relay to turn on/off the charger.
  3. dclermont

    New Member

    Mar 13, 2007
    This Link may help if you are handy, ory this one even give them a call.