Do i have problem with charging??

prince_77
prince_77 Solar Expert Posts: 31
Hello

after a first rain i went up to the roof to check my system, its seems that my charger (morning tristar ) showing green led light on, the sun is out, but when im checking the power level i see that i got 26V input instead of 40V, i went to the PV and check the exit and i got 41V. in the input of the tristar i got 26.7V
is that normal . is the system on float mode or something is wrong ?

thanks

Comments

  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    Re: Do i have problem with charging??

    IS the 40V the Voc or the Vmp of the panel?

    I can only extrapolate to my 12V power pack, Voc is 20.1V, Vmp is 17.5V, so 13V on my controller would indicate that the battery has had some moderate use, and that my Morningstar controller is in Absorb mode taking all my 80W panel can produce. Normal for me.
    prince_77 wrote: »
    Hello

    after a first rain i went up to the roof to check my system, its seems that my charger (morning tristar ) showing green led light on, the sun is out, but when im checking the power level i see that i got 26V input instead of 40V, i went to the PV and check the exit and i got 41V. in the input of the tristar i got 26.7V
    is that normal . is the system on float mode or something is wrong ?

    thanks
  • prince_77
    prince_77 Solar Expert Posts: 31
    Re: Do i have problem with charging??

    VOC is 40.1, my system is 24V system and when its charging i get something like 29V-28V inside and when in obsorve mode its 28V and u can hear the noise in the battery also
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Do i have problem with charging??
    prince_77 wrote: »
    im checking the power level i see that i got 26V input instead of 40V
    Where are you taking these measurements?
    prince_77 wrote: »
    i went to the PV and check the exit and i got 41V. in the input of the tristar i got 26.7V
    If this is as I read it, then you have a loss of over 14 volts between your solar panels and your controller, which is beyond HUGE!
    1) How many watts total, and what voltage rating are your solar panels?
    2) What size wire did you use, and how long is the run between your solar panels and your controller?
    3) What do you have for batteries? Total amp hours and voltage?
    4) What voltage are your batteries actually showing on your meter?
    5) What size wire was used to connect the Controller to the batteries, and how long are those wires?
    I'm asking these questions to get a better handle on what's happening, as something does not sound right to me.
    EDIT:(I now see that some of my questions were answered while I was writing this post, although the voltages you mention there, are different than your first post, which has me a bit confused)
  • prince_77
    prince_77 Solar Expert Posts: 31
    Re: Do i have problem with charging??
    Where are you taking these measurements?
    before i answer, i will like to say that the system work fine for the last 2 weeks and the charge was OK.

    If this is as I read it, then you have a loss of over 14 volts between your solar panels and your controller, which is beyond HUGE!
    1) How many watts total, and what voltage rating are your solar panels? 380W, 40V 8A total
    2) What size wire did you use, and how long is the run between your solar panels and your controller? the wires are pretty thick and the distance is short, like 12 feet
    3) What do you have for batteries? Total amp hours and voltage? 24 TMX 12V parralel + serial creating 24V 160AH
    4) What voltage are your batteries actually showing on your meter? 27V
    5) What size wire was used to connect the Controller to the batteries, and how long are those wires? same cable as the solar, pretty thick
    I'm asking these questions to get a better handle on what's happening, as something does not sound right to me.
    EDIT:(I now see that some of my questions were answered while I was writing this post, although the voltages you mention there, are different than your first post, which has me a bit confused)


    when measuring in the exit of panels i get 40V, measuring close to the controller get 26V
    nothing has change beside the rain yesterday
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Do i have problem with charging??

    It's all about when, where, and how you measure Voltages.

    40 Volts is not unusual Voc (Voltage open circuit) for "24 Volt" panels. It is meaningless for charging.
    The Vmp (Voltage maximum power - panels under load) will be less than this. Typically 8 Volts less, which means you've probably got some panels meant for GT applications with a Vmp around 32 - really too low for proper battery charging. What are the panels? (Make & model and/or output specifications).
    You should never measure Voltage out of the controller with panels attached but no battery.
    Normal charging Voltage on a "24 Volt" system is around 28.8 for FLA's. You may have the Tristar set for AGM's, which will charge at 28.4.
    In the process of charging, battery Voltage will go up to this level (the Absorb set point) and stay there for some time, then settle down to the Float Voltage.

    Please read through the battery FAQ's http://www.windsun.com/Batteries/Battery_FAQ.htm#Battery%20Charging to get an idea what should be going on. If we know what the panels' output should be then we can determine what is going on. And yes, wire size can make a big difference (to say nothing of rain which kills panel output).
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Do i have problem with charging??

    Sounds like you have a PWM charge controller (not MPPT).

    PWM charge controller is just an on-off switch that connects panels directly to battery.

    Panels are an illumation based current source so if you connect them directly to batteries the PV voltage drops to whatever battery voltage is.

    I bet when you say you get 40 vdc at panel you have disconnected panel from charge controller. The panel then goes to Voc. With no load on panels their voltage rises to point where the inherent diode of each cell conducts and shunts away all the illumination generated current. Temp dependent but it is about 0.65v times the number of series cells in the panel. (typically 72 cells for a 24 vdc battery system on a PWM charge controller).

    The PWM charge controller will start chopping on and off, the connection to panels, when batteries reach near their full charge voltage setting.

    An MPPT controller has a power conversion switching supply to allow the panel voltage to rise to its Vmp point. It takes the higher voltage/lower current and converts it to lower voltage/higher current at the batteries. The Vmp point is the voltage where just a small amount of the illumination generated current is allowed to shunt down the cells' inherent diode. Again temp dependent, but is normally about 0.5 vdc per cell.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Do i have problem with charging??
    prince_77 wrote: »
    when measuring in the exit of panels i get 40V, measuring close to the controller get 26V
    nothing has change beside the rain yesterday

    If you actually, really do have 40 volts coming out of your panels, and yet at the other end of that 12 feet of "pretty thick" wire where it enters your charge controller you only have 26 volts, you have a very serious problem.
    Have you actually measured the voltage under load, right at the panels and got 40 volts, or are you only going by what's printed on the back of the panel, stating 40 volts OC (Open Circuit) ?
    It's totally normal for the panel voltage to drop way back under load, but if you've really measured 40 volts there while under load, while at the same time only 26 volts at the input of the controller, then you have a serious problem caused by a bad/loose connection or connections, a bunch of broken strands in your cable, or your "pretty big" cable has only small wire inside thick insulation. Whatever the cause, if your measurements are right, you're loosing 14 volts X 8 Amps = 112 watts. Enough to cause a fire under the right circumstances.:cry:
  • prince_77
    prince_77 Solar Expert Posts: 31
    Re: Do i have problem with charging??

    thank u all for the info

    the wire is 7AWG
    the controller is PWM tristar 45
    OC of pannel is 40V - 4.5A - 190W
    crearting togheter 40V - 9A
    measure in output after joining panels - 40V

    measure before enter to controller - 26V
    i will need to go and check it again today, controller is on green stage mean battery full or in float mode , that how i left it in the morning