dump load

cocomitch
cocomitch Registered Users Posts: 17 ✭
in Solar Beginners Corner #1
hi guys/gals,

my brother in law has set up his system, he has 8 kyocera 120 watt panels and a whisper 200 wind generator, a xantrax 2500 set up for 12v, and a morningstar c60 charge controler. when he gets good sun, his batteries are almost boiling, be has ruines two banks so far, due to this. he needs a dump load, i imagine, so that when he reaches full on his batteries, that he does not keep frying them. what kind of dump load can he use, and how? starting to cost him a lot for not reading up, or listening to experience. I hope he will listen now. Any help you can give will be greatly appreciated!!
thanx
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #2
    Re: dump load

    How big is the battery bank (XXX AH at YY volts)?

    For a 200 watt wind turbine--Unless they live in an ideal wind area--It is difficult to believe the turbine is causing the battery overcharge (the dump load is there to dump wind turbine excess charging current).

    I would look at the 960 watts of solar panels and wonder if the C60 charge controller is properly setup and/or something else is going on (AC charger connected, not refilling batteries with distilled water once a month or so, or performing heavy equalization every week or two vs every month or two, etc.).

    The C60 is there to reduce/turn off charging current as the batteries reach 100% charge. For solar panels, there is no reason to setup a dump load.

    Is this bank in standby for emergency use, or is it in daily use (off grid)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #3
    Re: dump load

    From the description it sounds like something is not set right on the controller. And "c60" is a Xantrx controller, so I assume you mean the Morningstar TS-60?

    There should be no reason for a dump load unless the wind generator is totally unregulated and you get a LOT of wind.
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  • cocomitch
    cocomitch Registered Users Posts: 17 ✭
    #4
    Re: dump load

    Yes it is a morningstar c60, not sure about the ts part. His solar panels put in about 50 amps, when the batteries are full they start to boil, what could be wrong, the Gen is not realy a factor, they do get a lot of wind but it is when there is a lot of sun that this occurs. Any ideas of the solution? Thanx
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #5
    Re: dump load

    There is no such controller as a MorningStar C60... There is a TS-60 both in PWM and MPPT versions.

    In any case, measure the voltage of the battery bank when charging. It sounds like the charge controller is not programmed correctly (too high of charging voltage), there is a broken controller, or something is miss-wired.

    When charging the battery voltage should be:
    • ~14.2-14.5 volts when charging a battery (maximum voltage in bulk/absorb charging states).
    • ~13.7 volts when battery is fully charged and "Floating" (charger backs off on battery charging voltage once the battery is fully charged).
    • ~15.x volts when equalizing (only done once every month or three--don't equalize often or for long periods of time--is very hard on a battery bank).
    • ~12.7 volts after battery has "rested" for several hours without charging or loads.
    • ~12.0 volts for 50% charged battery (resting voltage).
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: dump load

    He's not running both the turbine and the solar panels through one controller, by any chance? That's bound to screw things up as most MPPT controllers don't deal with wind power well. PV's do not require a "dump load", but wind does. Both require functioning controllers, and it certainly sounds like that is what is missing in this system. The Morningstar may be set wrong or fried.
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  • cocomitch
    cocomitch Registered Users Posts: 17 ✭
    #7
    Re: dump load

    how can we test to see if his ts-60 is fried? in his owners manual it talks about charge controler and diversion mode, in diversion mode it says that the excess current will be diverted into a load as not to overcharge the battery bank. would that be a dump load? what is the difference between pwm and mppt? I know these are basic questions, but i want to make sure he has all the right information, i appreciate all your help. There is definnately something wrong with his system, on the weekend, i will make a diagram of his wiring configuration, possibly wired wrong too, hehe, hope not. thanx again!
    his battery bank is 4 l16 batteries rated at 395 amps 6 volts set up for 12v, forgot to mention, it is off grid!
    he has a seperate contoler for the wind generator, came with the generator.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #8
    Re: dump load

    Here is a couple of quick FAQ's for charge controllers:

    All About Charge Controllers
    Read this page about power tracking controllers

    Some charge controllers actually can be configured for both "normal operation" between solar panels and batteries... The charge controller basically controls the current from the solar panels to the battery bank--If the battery voltage is low, the controller allows more current through. If the battery is full--the charge controller reduces the amount of current supplied to the battery bank.

    For solar panels, this is just fine... You can turn the current on or off and the panels are just fine.

    Horizontal Axis Wind Turbines, on the other hand, will overspeed if they are not connected to a load (for off-grid systems, typically the battery bank). The battery is there to always apply a load current/voltage.

    If, there where no load current, the HAWT would overspeed and can self distruct.

    So, a dump/diversion mode charge controller is connected to the battery bank. When the bank is full, the dump controller turns on and supplies power to (typically) a resistance heater--drawing the battery bank down some so that it does not get overcharged on a windy day.

    Normally, you would have two controllers. A series solar panel charge controller for the PV panels. And a second dump controller (or solar charge controller setup as a dump controller) configured to draw excess energy on windy days.

    There are other types/configuration of charge controllers... And you can connect things differently (for example, connect the solar panels to a battery bank and use a dump mode controller instead--Less than ideal, but it can work).

    This can get a bit complex and confusing... So, getting the exact brand/model information and how they are wired up to the system would be a big help.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • cocomitch
    cocomitch Registered Users Posts: 17 ✭
    #9
    Re: dump load

    ok, i got him to realise what you were talking about, took long, lol. he has contacted a couple of guys up here that are supposed to be starting a company in solar products, they told him that he needed as many solar panels as the wattage of his inverter, so inverter is 2500 watts, they say he needs 2500 watts of solar panels. Is this right, i think they are trying to get him to buy for nothing. what is your opinion, which by the way matters, you have been on the money for everything i have mentioned,
    thanx
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: dump load

    No, that is not right. They're trying to get his money.

    The size of the inverter is set according to the maximum amount of power needed at any one time.
    The size of the battery bank is determined by the amount of Watt hours needed each day.
    The size of the solar array is set by what is needed to recharged those batteries.

    Else how could I be running a 3600 Watt inverter from 700 Watts of panels?

    To give them the benefit of the doubt, they might be talking about grid-tie inverters where the array size is determined by the inverter capacity.
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  • cocomitch
    cocomitch Registered Users Posts: 17 ✭
    #11
    Re: dump load

    ok thanx coot aka arc, lol i appreciate the advice, will tell him. thanx again!
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #12
    Re: dump load
    cocomitch wrote: »
    ok, i got him to realise what you were talking about, took long, lol. he has contacted a couple of guys up here that are supposed to be starting a company in solar products
    --- Yeah, everyone and their cousin seems to be doing that, unfortunately far too many are clueless, esp when it comes to battery sytems. ---

    , they told him that he needed as many solar panels as the wattage of his inverter, so inverter is 2500 watts, they say he needs 2500 watts of solar panels. Is this right, i think they are trying to get him to buy for nothing. what is your opinion, which by the way matters, you have been on the money for everything i have mentioned,
    thanx
    That is the silliest thing I have heard for a while.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,023 ✭✭✭✭
    #13
    Re: dump load

    As long as you're selling to babes in the woods it's a simple rule to remember.

    Ralph
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