What Voltage To Set Controller To?

Discussion in 'Solar Power' started by friar tuck, May 18, 2015.

  1. friar tuck

    friar tuck Funster

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    Hi I've recently installed a 200 watt solar system and I have noticed my mppt controller is adjustable for output voltage.it came set at 13.8v.im wondering if maintaining the batteries at a constant 13.8v all day will cause over charging and excessive gassing leading to electrolyte loss?
     
  2. Wildman

    Wildman Read Only Funster

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    it is adjustable so that you can change the setting for lead acid or gel batteries. My pair of leisure batteries have been set to 13.8 since 2001 and only just failed so I am confidently guessing it does them no harm, hee hee.
    12V LEAD ACID BATTERIES
    Although a battery is called a '12 volt' battery, its voltage varies from about 12.6 volts down to 10 volts when it is discharging and can rise to 15 or 16 volts during charging. It is very important, however, to limit the maximum battery voltage during charging otherwise the battery will be damaged. The battery voltage should not exceed 13.8 volts for long periods and 14.4 volts for short periods (8 hours maximum).

    Gel Batteries
    http://www.bblbatteries.co.uk/docs/hints_tips/Battery Charging.pdf
     
    Last edited: May 18, 2015
  3. friar tuck

    friar tuck Funster

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    Seems a reasonable length for a test period! I will leave it set at that it also feeds via a relay to the engine battery same principle as van bit relay so I assume the engine battery will be ok too?
     
  4. Techno

    Techno Funster Life Member

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    What Mppt is that?
    Mine charges at three different voltages depending on state of charge from 13.4 to 14.4 float bulk and absorption. If yours only charges at a fixed voltage it's not a true mppt.

    The float voltage for vented batteries with mine is 13.2 and for sealed 13.4 Gel 13.7
    Bulk charge for all is 14.3
     
    Last edited: May 18, 2015
  5. SomeoneElse

    SomeoneElse Funster

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  6. Techno

    Techno Funster Life Member

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    That is one of many frauds and even has the cheek to compare theirs to one that might actually be an mppt although that looks dodgy too :LOL:
     
  7. friar tuck

    friar tuck Funster

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    It's exactlyly that model .so hour saying it's a fraud! I'm wondering whether it is worth complaining to the supplier?
     
  8. Techno

    Techno Funster Life Member

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    Not really they know full well that people buy purely because they claim it is MPPT. They know full well that it isn't.

    Any MPPT has two toroidal coils that are amongst other components essential to the way they function. They are actually claiming that the one in their picture works less efficiently because of the single coil whilst theirs has none at all . They are both very poor.
     
    Last edited: May 18, 2015
  9. Techno

    Techno Funster Life Member

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    This is what you should expect of MPPT internals and 3 or 4 times more expensive
    [​IMG]
     
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  10. friar tuck

    friar tuck Funster

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    It will still do an ok job though ?
     
  11. Techno

    Techno Funster Life Member

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    Yes it will work as a regular PWM but I don't know how well.

    This is one of two videos


    Looks like its not a real PWM either
     
  12. cruiser

    cruiser Funster Life Member

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    thanks a lot techno100. I now know what to look out for.
     
  13. Techno

    Techno Funster Life Member

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    Having watched video 2 I'd bin it.
    Be sure to leave negative feedback!
     
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  14. SomeoneElse

    SomeoneElse Funster

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    I think its worse that that. I haven't check the internals but when I monitored its operation I found that it always ran the panel at the battery voltage plus 0.75volts, until the voltage originally mentioned is reached.
    I assumed that the controller was just a power transistor which is normally wide open and only gets modulated when the battery voltage rises. The curent is then reduced and the panel voltage rises along its IV curve. Very crude, at least a PWM controller would run the panel at an assumed (fixed) max power point.
     
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  15. Techno

    Techno Funster Life Member

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    This is what a real mppt does. I have 300 watts of solar and under the sky that was available for this picture (my panels are only rated at 5.5amp output each) here it has massaged the watts and voltage (simplistic) to increase the current to 14 amps where a PWM would be sending 11 at maximum. I have seen 22 amps at times.
    [​IMG]
     
  16. scotjimland

    scotjimland Funster Life Member

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    Hi Andy

    My Hymer came already fitted with 2 x 80watt panels and a EPHC 10A PWM controller.. like this http://www.ebay.co.uk/itm/EP-Solar-...228?pt=LH_DefaultDomain_3&hash=item3f4c973f64

    it says it has "Pulse Width Modulation with four stages of charging" and I've witnessed this happening on the battery voltage meter .. so don't doubt the claim..

    question is, would I be better fitting an MPPT ?

    what make / model is your controller ?

    I may fit more panels depending on how it goes this year .. in which case I would need a bigger controller anyway..
     
  17. Techno

    Techno Funster Life Member

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    The one I've used since its earliest incarnation is now used by dozens of people across a number of forums. It has been constantly improved over the last 4 years to the current model. It is available as 200 or 300 watt and will cost circa £100 inc Parcelforce fee if unlucky. Personally these are all I use now.
    This is mine but look at sellers other items for the slightly cheaper 200 watt
    http://www.ebay.co.uk/itm/140661388530?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
     
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  18. Techno

    Techno Funster Life Member

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  19. scotjimland

    scotjimland Funster Life Member

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    Thanks @Techno100 .. will probably upgrade it soon, good price..
     
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  20. Techno

    Techno Funster Life Member

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    After sales service as been tried and tested and first class (y) Big difference between Taiwan and China
     
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