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Solar panels Mystery

Discussion in 'Ask A Beneteau Owner' started by hookway, Oct 7, 2017. Add this thread to a FAQ

  1. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    Hello All,


    The facts are:


    1. 3 new AGM batterys, rated at 110 Ahr each. Normally charged by a multi stage charger


    2. The power meter reads 390 Ahr for the 3 of them (not 330 as expected), and is very accurate measuring the load in and out


    3. Above 295 Ahr, the batteries do not charge by the engine alternator

    Below 295 Ahr batteries charge OK by the engine alternator


    4. The Solar Panels (2 x 100W) do not seem to charge the battery at all, no movement from the meter


    That’s the real concern.


    They are connected properly, when connected directly to floodlights (to test them) they work. They increase the voltage of the batteries up to 13.6 on a sunny afternoon, but have no effect on the Ahr reading. How can this be?


    Any clues on resolving this would be greatly appreciated.
     


  2. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    What solar charging controller do you have?
     


  3. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    an intelligent PWM, by www.ecosolarpanel.com (its Chinese). I don't think the fault is with the controller because I've independently tested the voltage it reads with the multimeter, its correct
     


  4. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    It could be that the connection of the solar controller to the batteries is bypassing the shunt that is used to measure the battery IN/OUT Ah. This shunt is usually on the negative side of the battery bank.

    If the solar panel is raising the battery voltage, it's charging the batteries. I've seen mine much higher than that, FWIW. It could be that the solar controller is detecting that your batts are charged, and is just entering float mode, which would align with 13.6V.
     


    hookway likes this.
  5. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,486 posts, 327 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    Let's assume...

    On a bright sunny day at solar noon local time the sun is due south and at its zenith. This will produce from your panels the maximum voltage and current to the controller. Since I don't know the make of the panel I will also assume it to be around 17vdc. With that, the current assumed to be 5.37 amps (generic voltage and current of average solar panel).

    So both panels are now produce combined 17vdc and 10.7 amps. If the batteries are not discharged deep enough, there would be no reason to charge them. So maybe the controller is not seeing a low enough voltage for it to kick in. It could be producing a trickle charge or, like you see, nothing at all.

    Have you tried just putting a single battery with low voltage (like a motorcycle battery) on the panels to see if it will charge it? I know you said that the charger is working because it burns a light on the load outputs.
     


    hookway likes this.
  6. Ron20324

    Ron20324

    Joined Jan 22, 2008
    5,556 posts, 352 likes
    Beneteau 323
    US Annapolis MD
    WHY DO YOU HAVE 390, NOT 330- THE POWER OF THE THREE BATTERIES. YOU ARE TRYING TO CHARGE TO 390, WHICH THE BATTERIES CAN NOT ACCEPT. Do you have a smart charger on the alternator?
     


  7. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
     


  8. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    The voltage was way down at about 12.5 and rose to 13.6 so I think its safe to assume its charging. No, I haven't yet tried a low voltage battery
     


  9. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    I really don't know why it reads 390! Yes, the alternator charger seems smart, its a recent model 2012 Yanmar and seems to regulate the voltage and incoming charge OK.
     


  10. jssailem

    jssailem

    Joined Oct 22, 2014
    3,190 posts, 592 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA


  11. jssailem

    jssailem

    Joined Oct 22, 2014
    3,190 posts, 592 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    What brand of alternator seems smart?
    It is not the alternator but the regulator that controls charging. Some alternators have internally built regulators. These are generally dumb (not programmable or temp sensing units).
     


  12. Larry -- DH

    Larry -- DH

    Joined Jun 14, 2010
    127 posts, 39 likes
    Quorning Dragonfly 1200
    US home
    I think jviss has the right answer.

    Also, I'm not clear about why you think a battery monitor would measure the AH capacity- that's something that you need to input on setup, after that all it can do is measure amps flowing in and out, and calculate an estimated AH reading. The reference to Mainsail's post mentioned above explains why these meters are inaccurate.
     


    hookway likes this.
  13. JohnShannon

    JohnShannon

    Joined Jan 4, 2010
    606 posts, 38 likes
    Farr 30
    US San Francisco
    Seems like the alternator and the rating of the batteries agree. The alternator won't charge past 295 Ahr because that is the limit of the battery. Your monitor needs to be told the actual capacity.
     


    hookway likes this.
  14. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    Thank you all for all the advice, I'm satisfied that the meter is not including the readings from the solar panel, only from the alternator.
     


  15. hookway

    hookway

    Joined Dec 28, 2016
    27 posts, 0 likes
    Beneteau Oceanis 400
    NZ Auckland New Zealand Auckland
    Agreed, jviss has the right answer and AH capacity- that's something that you need to input on setup.
     


  16. JimInPB

    JimInPB

    Joined Aug 22, 2017
    130 posts, 16 likes
    Hunter 212 & 170
    us Florida West Palm Beach
    Is the meter new also? If not, did it previously work well with an older bank of the same AH capacity?

    Beware readings on multimeters, especially digital ones, when checking a PWM outputs. Sometimes they are sort of accurate. Sometimes they are very much not even in the ball park. Unless you have a meter with an oscilloscope function, you can't really know what a PWM output is doing.

    I don't know what AH meter you have & I don't know what solar controller you have, but if the solar charge feed to the battery bypasses the AH meter sensor, then it would not be beyond the realm of my imagination for some automatic algorithm in the meter to calculate that your bank has more capacity than it really does after the meter sees good voltage remaining after it saw more power going out than it saw go in.
     



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