Plug in chargers vs solar panel polarity

stmarstmar Solar Expert Posts: 330 ✭✭✭
As I stated in a previous post a while ago I ruined a lawn tractor battery by using a plug in charger pig tail with a solar charger. Can anyone explain why they have different polarities for plug in and solar pig tails? Pig tails are opposite polarity, you would think there would be a standard. My Battery Tender model identifies polarity so you can plug any configuration into it but the YUSA model is specific and my two solar chargers are specific but opposite from the YUSA.


  • BB.BB. Super Moderators, Administrators Posts: 29,637 admin
    Do you have any pictures/links to the problem?

    In general, you connect + terminals all together (whether loads, chargers, solar panels, etc.)--Of course with proper fusing/breakers as required. And all - terminals are connected together.

    Solar panels are "giant diodes"--And when connecting them, you are really connecting the diodes in "reverse bias" mode. No (or very little current) will flow when connected to the battery. If you connect the solar panel backwards, then the diodes are "forward biased" and will conduct maximum amount of current (near short circuit current). And can/will ruin the panel (fuses/breakers or not).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • stmarstmar Solar Expert Posts: 330 ✭✭✭
    I was wrong about the YUSA model 12V900, it does have polarity protection and will charge no matter what the orientation.
    It is not really a problem as such, I am just trying to make heads or tails out of the different orientations from battery tender chargers to solar chargers, they are opposite and I was just wondering why.
Sign In or Register to comment.