MPPT Tristar 60 - Positive terminal burning

Jakachira
Jakachira Solar Expert Posts: 47 ✭✭
I have the Tristar 60, the MPPT. 3x150watts of panels delivering about 25amps to a 12v battery bank. The panels are connected in series at 53Volts and 7amps.

My batteries size is now 306ah (102ah x 3) and are 3 weeks old.

I am experiencing a problem.

(1) The positive terminal in the controller got a serious burnt so much that the cable was melted on the terminal. What could be the problem with this? My cables are very thick (16mm thick).

(2) My final battery voltage after usage is 12.4V (read after 2hours) but then in the morning the voltage when charging breezes to 14.7V. Only an hour for MPPT charge stage therefore the Absorption stage is very long. Why do my batteries not stay in MPPT for long? In the night the voltage tend to drop so quickly with a load of just 10amps

Your help will be much appreciated

Thanks guys.

Comments

  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    1) Usually when a terminal burns like that is because it's not tight. A loose connection overheats. Check it close to see if you melted the solder out of the circuit board, been there done that. You might have to re-solder it.

    2) MPPT is only active during the BULK Stage.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    The two problems (burned cable and apparently fast charge) may well be related.
    You don't say if the burned terminal is the input from the PV, or the output to the battery. I'm going to guess the + output terminal to your battery bank.
    If so, it was almost 100% sure caused by an improper, poor connection that resulted in a resistance which in turn caused heating/arcing of the terminal, and if you aren't using the separate terminals with separate wires for battery voltage info to the controller, the battery voltage would appear to the controller to be going up faster and higher than it really is. Thus the early switch to absorb + heat buildup at the + terminal + undercharging of the battery resulting in quick voltage drop under load at night.
    PS: I said "almost 100% sure" because there is a slight, very slight chance it could be a bad/poor connection between the terminal and the actual circuit board.
    Get it fixed before you use it again, or arcing could well ignite a devastating fire.
  • Jakachira
    Jakachira Solar Expert Posts: 47 ✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    I see. You must be spot on. These voltages irrigularities and burnt cable means I have poor connections. The +ve terminal in question is to the battery bank.

    I will have the cables re-connected securely. Thanks for the advice, guys, that explains it surely.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    One thing to be aware of - - - if the end of the cable is burned, so will be the inside of the connector it was attached to. You may well have to scrape out blackened metal from the connector so the new clean wire makes good secure contact with good clean metal in the terminal - - - otherwise excess resistance will remain and the problem could easily return.
    Good luck and let us know how you make out.
    Peace.
  • Jakachira
    Jakachira Solar Expert Posts: 47 ✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    Ok, guys. I re-wired the connection and it looks very secure now and I have put Battery Voltage Senses to MPPT to the battery.

    Things are working alright now. And the voltages are stable now. I will keep an eye on it.

    Thank you guys for the solution.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: MPPT Tristar 60 - Positive terminal burning

    AWESOME! Great to hear all now appears good.
    Thanks a lot for the update :D