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Solar Charge Controller: is this the right MOS-FET and can this board be salvaged?

Discussion in 'Troubleshooting and Repair' started by rudykruger, May 18, 2019.

  1. rudykruger

    rudykruger

    3
    0
    May 18, 2019
    Let me preface my first post here by clarifying that I am not an electrical engineer of any discipline. I am a mechanical engineer and usually I would use a hammer to fix problems.

    The attached pictures show the circuit board in a small 260 Watt PWM solar controller that I inherited on a sailboat I've owned the past 8 months. This is a secondary charge controller used to maintain engine starter batteries. This controller has one (relatively) unique feature in that it has the ability to charge 2 separate battery banks from a single solar input, and at one time it was hooked to 2 starter batteries. Only one battery charge circuit ever worked, and when I pulled it apart it became clear why. The MOS-FET on the second battery connection was overloaded at some point and is kaput.

    The charge controller is an inhouse brand (InovTech) of a French motorhome, caravan and accessory company. I've not managed to find any specifications or detailed documentation online, but I assume the 260 Watt rating is the maximum nominal 12V solar panel input power.

    EDIT to add: for what it's worth, I have this charge controller hooked to a single small 20 watt flexible solar panel used solely to maintain starter batteries. Usually this controller will see a max of 1.5 amps. The overload happened with a previous owner, and the boat now has a separate, much larger 1000 watt MPPT controller for the house battery bank.

    It is very faint, but the burnt out MOS-FET is marked 2N06L07 and GAA702.

    So my first question: is the N-channel Infineon IPB80N06S2L-07 below a match? It is marked 2N06L07. This MOS-FET is rated for a maximum voltage of 55V, a maximum current of 80A, BUT it's power dissipation is only 210 Watt.

    https://www.infineon.com/dgdl/Infin...n.pdf?fileId=db3a304412b407950112b43232455757

    Second question: to the experts on this forum, do you think this circuit board can be salvaged if I replace the MOS-FET? And possibly attach an external heat sink?


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    Last edited: May 18, 2019
  2. bushtech

    bushtech

    888
    139
    Sep 13, 2016
    Please post a photo of the other side of the pcb as well. I see some rusty bits top side.
     
  3. rudykruger

    rudykruger

    3
    0
    May 18, 2019
    Here's the other side of the PCB. This charge controller lives in a marine environment but the corrosion is superficial. Apart from the blown Battery 2 circuit everything works.

    [​IMG]
     
  4. bushtech

    bushtech

    888
    139
    Sep 13, 2016
    Hopefully someone with more knowledge on mosfets than me will be along to help.
    But if those pads the mosfets are soldered to are heatsinks then you have lost the heatsink under the damaged fet. In that case I would suggest you stand your replacement fet up and fit a decent heatsink to it. There is little going on on the underside under that fet so you can get a decent fit done there.
     
    rudykruger likes this.
  5. rudykruger

    rudykruger

    3
    0
    May 18, 2019
    Thanks for the reply

    I believe the PCB pads - now separated and lifted from the board and partially destroyed - are both heatsinks and a fourth leg on the transistor (drain?). I was hoping gobs of solder where the copper pad has separated from the board might do the trick, build a new pad so to speak.

    And then finish it off with a heatsink attached over top of the fets.
     
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