Question about a charge controller

bethpeppermintbethpeppermint Registered Users Posts: 3 ✭
in Off Grid Solar & Battery Systems #1
Hello all, we have the following small set up:charge controller is a Xantrex C60 Charge Controller. 12 or 24v. It is set to 12v. Max charge at 14.4v.
2-Panels are solarworld SW 260 mono.
Battery's are 2-6v. 235 amp hour wired in series to get 12v.
My issue is that the batteries are not getting a full charge at any point. I took everything apart and tested. The results are:
33v. from the panels (cloud cover so that is about right as they are 38v. Max.)
12.6 at the connection in the charge controller, 12.5 at the battery connection in the charge controller and 12.4 for the battery.
At one point they were all reading the same.
If there is no load on the battery it will not charge or charge very slowly. If there is a slight load as in an inverter running or a 12 v. Light it will charge faster but never gets above 12.8.
Shouldn't the output from the charge controller be 14.4 and the battery increase up to that or am I missing something?
Thanks for your help.
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Comments

  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    edited November 2015 #2
    What type of batteries? How are you determining whether the batteries are fully charged or not?

     If they are flooded type have you checked the sp gr of each cell, truly the best method to determine state of charge. Voltage readings can be misleading. Is your voltage meter accurate? When you state that with no load on the battery it does not charge or only charges slowly, that is the behavior one would expect if the battery was full. A battery voltage of 12.8, after resting for several hours would be considered fully charged if it was a lead-acid battery. 


    When the CC is putting out 14.4 volts you will bet that voltage at the battery terminals. If you disconnect the CC the voltage will fall over a period of several hours to about 12.7 to 12.8 on a good battery. I have a pair of golf cart batteries in series that take nearly a day to fall from 13.5 Itaken off float at that point) to 12.7, sitting idle. 

    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • bethpeppermintbethpeppermint Registered Users Posts: 3 ✭
    #3
    Only getting 12.5 out of the charge controller. It is set at 14.4. Haven't disconnected the battery from the charge controller to test and not sure if it would hurt the charge controller to do so. Hubby has a hydrometer at work of course. :( Batteries are not going above 12.5 at any time. I would expect them to go up then drop but they never go up. Can I disconnect the battery and the cc output should show 14.4 or would it show nothing cause there is nothing hooked up?
    Really wishing I had gotten the faceplate with the readings in it...... will be ordering it. I like to have more data to work with.
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  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    edited November 2015 #4
    Did this setup ever work? Or is this the initial setup?

    If it has never worked I suggest disconnecting everything. Then start the reinstallation following the steps precisely in the order as listed in the user manual. That starts with the jumper settings before anything gets connected. 
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • bethpeppermintbethpeppermint Registered Users Posts: 3 ✭
    #5
    That was haw it was connected initially. The more I learn about this I am thinking this is still correct but because the cc is not an mppt controller. It will charge them up but not fast. Thinking I may need to get a mppt charge controller...
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  • ThomThom Solar Expert Posts: 195 ✭✭✭
    #6
    Yes u should have a Mppt controller . A Kid would work well I think

    thom
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added [email protected] 100w panel with a midnight brat 
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  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
    bethpeppermint said:
    That was haw it was connected initially. The more I learn about this I am thinking this is still correct but because the cc is not an mppt controller. It will charge them up but not fast. Thinking I may need to get a mppt charge controller...
    Yes. With a PWM CC you are getting at best less than 1/2 of the available power from the panels. If the panel Voc is nominally 38V, then the Vmp will be about 30.4V. That means that at a 12V battery terminal voltage you will only get 40% of the potential panel power.
    With an MPPT controller and the same panels you will easily get twice the power into the battery bank.

    Also, FWIW, the voltage output (both Voc and Vmp) of a panel is not particularly sensitive to the amount of light hitting the panel over a range from full sun to full overcast. What will decrease is the current available from the panel.
    SMA SB 3000, old BP panels.
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