Solar controller and temp adjustment

Discussion in 'Solar Power' started by sallylillian, Jun 5, 2016.

  1. sallylillian

    sallylillian Funster Life Member

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    I have now realised that there is a conflict between my CBE solar controller and my Victron Inverter/Charger. The CBE unit has fixed charging characteristics dependent on battery selection and so the GEL option was selected by the factory giving a float of 13.8. So my Victron is far more sophisticated and although the float is set at the same 13.8 this is the float at a battery temp of 25c. Now the Victron has a temp sensor at the battery and increases/decreases the the voltages according to the temperature at the battery, as is the correct procedure. Once we start experiencing in excess of 25c the Victron lowers the float but of course the solar controller does not adjust so when on EHU the Victron drops off but the solar keeps banging away sometimes going to absorption voltage.
    This long term will cause my AGM's to experience an early death. Is there a way that the CBE unit or another can use temp sensing to manipulate voltages?
     
  2. Lenny HB

    Lenny HB Funster

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    Just having you AGM's on Gel setting with cause an early death mine lasted 18 months, replaced them with Gel's.
     
  3. sallylillian

    sallylillian Funster Life Member

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    The Varta spec sheet says 13.8 float and I configured the Victron for AGM and with the correct absorption voltage. My issue is with the solar controller it's rather crude in my opinion and I was exploring on here what other may have with temp sending, or is there not such a beast?
     
  4. John Laidler

    John Laidler Funster

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    You could try emailing Victron. I asked them a question about my solar controller and got a very helpful reply, in English, back promptly. Of course, they may just suggest you buy one of their solar chargers! They are sophisticated things, mine alters it cycle during the day and sets the voltage automatically.
     
  5. sallylillian

    sallylillian Funster Life Member

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    I had been considering that but my Flair has a CBE customised main panel which takes a feed from the CBE controller. Does your Victron have temp sending?
     
  6. Techno

    Techno Funster Life Member

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    Better fitting the Taiwan mppt. The charge voltage is governed by the state of the battery. It won't just throw high voltage at the batteries as that is pointless and how PWM will play the game.
    The mppt will track the voltage at which it can deliver maximum power
    So if the battery is reading 12.4 it will charge at 12.5 or 12.6. It converts the excess voltage into more current.
    When the batteries get nearer fully charged this will be up at 14.4 or whatever is required for the battery type.
     
  7. Techno

    Techno Funster Life Member

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    Perfect example here
    Voltage is just high enough for current to flow (higher than the batteries current voltage) but the excess voltage is converted into more current.
    A PWM would be firing in 14.4 at VERY much lower current.
    [​IMG]
     
  8. sallylillian

    sallylillian Funster Life Member

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    Andy my point is the float voltage level which the charger(s) maintain. The spec on most batteries for float is temp dependant and good chargers with temp sensing will adjust the float lower when temp is over 25 and higher when colder.
     
  9. Techno

    Techno Funster Life Member

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    I don't bother with temperature. I've used these since late 2010 and on mark III version My batteries are always tip top
     
  10. Techno

    Techno Funster Life Member

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  11. John Laidler

    John Laidler Funster

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    You can get remote sensors for some Victron models, mine just measures the ambient temperature at the controller, but it only does it when it isn't under load, so it isn't too clever as this means it won't be measuring when the sun is out!
     
  12. Techno

    Techno Funster Life Member

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    The Mppt works on voltage and charges according to this. If the voltage goes up and down due to temperature it is still charging according to this "tracking"
     
  13. sallylillian

    sallylillian Funster Life Member

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    I am in at the factory next week for some warranty stuff, I think I will dump this on them!
     
  14. Techno

    Techno Funster Life Member

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    PWM technology or lack of may benefit from a temperature sensor but mppt doesn't need one
     
  15. sallylillian

    sallylillian Funster Life Member

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    But the controller has set floats according to your manual it will work to achieve float and then maintain it. Temperature has an effect on the float level the battery requires.
     
  16. Techno

    Techno Funster Life Member

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    Appen aye but it will have charged them first.
    No point having too much in the frills department. At the end of the day a solar charger does not have an un interupted power source
     
  17. John Laidler

    John Laidler Funster

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    You confused me with that. The tracking of an mppt controller is about the solar panel voltage not the output voltage. The controller will allow the PV panel(s) to run at a voltage where maximum power is generated. Which the controller then turns into a lower voltage at a higher current - assuming the batteries and/or load need it and of course at a voltage ideally to match what the batteries need, which is what we are talking about.
     
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  18. Lenny HB

    Lenny HB Funster

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    If your Victron solar charger has a proper AGM setting and is your main source of charging your batteries will probably survive, what appears to kill them is when charged by a Gel charger they never get a full charge. Don't know the characteristics of the CBE unit but an Electroblock charges to 14.3 v and holds at 14.3 for one hour before dropping to 13.8v for wet cells and for gel it holds at 14.3 v for eight hours. AGM's need to be taken up to 14.7/14.8 v for a full charge and using the recommended Gel setting fecks them.
     
    Last edited: Jun 5, 2016
  19. Techno

    Techno Funster Life Member

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    In my experience it is doing both.
    I'm no wiz at electronics but it does have twin toroidal transformers
    [​IMG]
     
    Last edited: Jun 5, 2016
  20. sallylillian

    sallylillian Funster Life Member

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    What I have when on EHU in higher temps is the solar in effect fighting with the Victron and charging at a too higher voltage. One of the killers of AGMs.
     
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