system not working properly

cocomitchcocomitch Registered Users Posts: 17
Hi guys/gals,

I have written a few times with problems my brother in law is having with his sytem, and have had some good advice from some of the members. I do not know if i can attach a diagram to this thread, so i will try to explain what he has.
To start with he has 8 kyocera panels 4 are 120w and four 125w.
they are set up on 2 towers that he rotates as the sun changes in the sky, they are set up in paralel, all being attached together at the tower, then run to the xantrex tc60 charge controler, then it goes to 4 L 16 batteries, set to 12v.
He also has a whisper 200 wind generator, which goes to it's controler and then also to the batteries.
From the batteries, it all goes to a xantrex inverter charger set to 12 v, from there it goes to a small panel to distribute the 115.
There are also a fuse between the positive coming in on the solar panels before the charge controler, and another fuse between the positive on the battery and the inverter.
this all being said, he will charge his batteries to 12.7v during the day and in the morning they are at 11.9v
The only load that he has on them is a fridge, 115v at 1.5 amps, and a small water pump that pumps his water through his radiant floor, that takes 115v down to 24v through a transformer that is rated at .5 amps.

I found how to attach a pic, so please have a look and if you have any suggestions, please let me know, i appreciate any help you can give, he is starting to drink, it bothers him so much,

Thanx,

Mike

Comments

  • icarusicarus Solar Expert Posts: 5,345 ✭✭✭✭
    Re: system not working properly

    A 1.5 amp load at 120 VAC translates to a 15 amp load on 12 vdc, or ~ 180 watts. running 24 hours would 4.3 kwh. Add in the pump that might draw .5 at 120 would be 5 at 12, or 60 watt. 24 hours would be another 1440 wh for a total of about 5.7 kwh/day.

    The rule of thumb is, you can take the name plate rating of the PV, divide that by 1/2 to account for all system loses, multiply that number by 4 to count the average number of hours of good sun one can count on.

    So your system (PV only) of ~ 900 watts might look like this, 900/2=450*4=1.8 kwh/day average. So you can easily see, that even if the wind were reliable, you are probably chronically undercharging the batteries, and have probably killed them.

    Good luck and keep in touch,

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 29,698 admin
    Re: system not working properly

    For clarification... He charges the batteries to ~14.2-14.5 volts during the day--And at night, after a few hours, the resting voltage of the battery bank (no loads, no charging) is 12.7 volts...

    If the battery bank is being charged and never rises about 12.7 volts during the day--You have some problems... That may be one or more of the following:
    • Batteries are less than 80% capacity at the end of the day
    • Insufficient charging current:
    • Solar Wind not working correctly (bad wiring connections, faulty devices, programming error, etc.)
    • Too small of solar array / wind turbine
    • Too large of battery bank
    • Meter Calibration issue / bad meter / weak battery
    • Too much DC loads during day preventing enough current from reaching the battery bank
    • Simply too much load with too little charging current--Deficit Charging.
    • Leaving 2,500 watt inverter on 24x7... These can draw 30 watts or more (check specifications) just idling (no AC loads)--a significant load on a small system
    30 watts * 24 hours per day = 720 Watt*Hours per day just to power up the inverter (just guessing/making an example).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: system not working properly

    As Bill said, you really need to know what the final voltage of the batteries are and how much current they are accepting at that voltage. Do you know what the charging parameters are on the charge controller, voltage setpoints for absorb and float, and absorb time?

    That Fridge is no small load for that kind of battery bank, and likely it's drawing too much to be used on that size battery. It's hard to say for certain how much it's drawing on a day to day basis, depending on how often it's actually running; but even just running 50% of the time it's probably drawing between 150-200ah/day. After inverter losses, and possible voltage drop issues, etc, my guess would be more than 200ah; which means that he's using 30% or more of his battery capacity every day just on one load (might be more than this even).

    I'd also say that if he doesn't have a battery monitor of some sort, that would be a great place to start. Get an exact handle on how much energy he's harvesting between his solar array and his wind turbine, as well as exactly what his loads are drawing on the battery bank. It's possible that he might have some other loads that he's not aware of; i.e. "phantom loads".
    Good luck
  • DerikDerik Solar Expert Posts: 82 ✭✭✭✭
    Re: system not working properly

    I have never seen a fridge run all day 24 hours. I bet it's only running about 25% of the time. I have a full size fridge and it only draws 100 watts and runs less than 25% of the time.
  • icarusicarus Solar Expert Posts: 5,345 ✭✭✭✭
    Re: system not working properly

    The point however is to accurately define the loads. Until you know what the fridge and pump systems actually consume it is pretty hard to know if your system is any where near balanced.

    Tony
  • cocomitchcocomitch Registered Users Posts: 17
    Re: system not working properly

    Well, from what i am getting here, his first order of business is to get a battery monitor, and find out how much is going in and out. I cannot imagine a fridge that uses 1.5 amp an hour using 200 amps a day. it is probably only in use 25% of the time, however a monitor will tell us. I was not aware that the inverter took that much power sitting at idle, i will have to let him know that too. his batteries rarely go over the 12.7 range, so i am thinking he screwed up his batteries too. could be a culmination of a series of things. i will get back to you on his consumption and possible consumption needs.

    Thanx guys!!!!!!!
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: system not working properly
    cocomitch wrote: »
    Well, from what i am getting here, his first order of business is to get a battery monitor, and find out how much is going in and out. I cannot imagine a fridge that uses 1.5 amp an hour using 200 amps a day. it is probably only in use 25% of the time

    Remember to keep the amps and volts straight: 1.5 amps @115 volts would translate to just shy of 15amps at 12 volts, and factoring in inverter efficiency of say 90% (an estimate) you would have a draw of closer to 16 amps.

    If his batteries are rarely getting up higher than 12.7V, then thats absolutely a bad sign. I think Tony's illustration of deficit cycling is probably on the right track. Given that he has almost 1kw of PV (not even a clue what the wind turbine may or may not contribute), I'm surprised that his batteries are not getting charged from those alone. This would lead me to think that either the fridge is running more than he might think, or that perhaps there are some other loads drawing power. You also mentioned nighttime loads, but how about daytime loads?
  • BB.BB. Super Moderators, Administrators Posts: 29,698 admin
    Re: system not working properly
    cocomitch wrote: »
    Well, from what i am getting here, his first order of business is to get a battery monitor, and find out how much is going in and out. I cannot imagine a fridge that uses 1.5 amp an hour [at 120 VAC] using 200 amps a day [15 amps * 24 hours * 25+% duty cycle = 90+ AH per day @ 12 VDC]. it is probably only in use 25% of the time, however a monitor will tell us. I was not aware that the inverter took that much power sitting at idle, i will have to let him know that too. his batteries rarely go over the 12.7 range, so i am thinking he screwed up his batteries too. could be a culmination of a series of things. i will get back to you on his consumption and possible consumption needs.

    Thanx guys!!!!!!!

    Remember the working voltage... The refrigerator runs at 120 VAC, and the battery bank runs at ~12 VDC... So, at the very basic level, 1.5 amps at 120 VAC is equivalent to 15 amps at 12 VDC:
    • Power = Voltage * Current
    Add running the battery down to 10.5 volts and 85% efficient inverter (plus a 1.25 safety factor for wiring and fuses)--and you are talking about some large 12 volt current / Amp*Hour numbers. Let alone surge current support...

    Yea, if he is not charging the batteries around 14.2 to 14.5 volts at least for 2-6 hours every couple of days--He is "deficit charging"--basically never fully recharging the battery bank and running the risk of severe sulphation over the coming months/years leading to early battery death (from loss of capacity).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cocomitchcocomitch Registered Users Posts: 17
    Re: system not working properly

    according to the spec sheet on the inverter, it only takes .5w.

    does this sound right?

    Standby mode power draw
    (no output, display off)
    ≤0.5W
  • BB.BB. Super Moderators, Administrators Posts: 29,698 admin
    Re: system not working properly

    That is "powered down" or "inhibit" mode... It still draws 0.5 watts when everything is off...

    In "search mode" (looking for >6-8 watts of AC load) it will probably take more. And if idling (no AC load), it will probably draw in the 6-30 watt range (need exact model for proper specs.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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