What Voltage should my control panel be showing?

Discussion in 'Solar Power' started by Robert Clark, Jul 31, 2016.

  1. Robert Clark

    Robert Clark Funster Life Member

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    Hi Guys

    Yesterday I decided to test to see how long it would take my solar panels to re-charge my batteries after use.

    Got 320ah solar and 360ah gel batteries

    At the beginning of the test (early morning) the MH control panel showed the battery voltatge at 13.1v
    I ran my air conditioning for 1 hour
    After turning off the A/C the battery voltage showed 12.7v
    In the middle of the afternoon the battery voltage had only increased to 12.8v (it was a very cloudy day)
    The charge indicator neon on my Victron solar controller MPPT 75/15 controller was solid yellow (not flashing) which shows that its on 'float charge'

    I was expecting the reading to be higher, so I attached a multi meter to the output of the solar controller, which showed 13.3V

    So I'm wondering why the output of the solar controller was higher than the voltage being picked up my the MH control panel?

    Why the solar controller was only showing as 'float charge' when I'd been running the A/C for an hour?

    Will the solar panels ever return the charge state to 13v, or will they charge to a lower level than the battery charger would, when connected to EHU?

    Thanks
    Robert
     
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  2. John Laidler

    John Laidler Funster

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    I've got the same controller as you (but just the one! :)) and my battery voltage reads 13.6 when on float. The sun is shining at the moment and this is what it is showing with a charging current of around 0.1 amp.

    Edit: Just checked again and it is showing 13.8 volts, same 0.1 amp charging current.
     
    Last edited: Jul 31, 2016
  3. PhilandMena

    PhilandMena Funster

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    I will have a stab at this! I suspect your system is fine and working as it should. When you ran your AC you would have been drawing power from both the solar power bank and Hab battery bank and I suspect little was taken from your batteries. When you place a load on your batteries they will not provide an accurate reading, they need to be at rest with no load on, for a few hours before you can accurately measure them and I suspect this is where the anomaly is coming from.
     
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  4. Robert Clark

    Robert Clark Funster Life Member

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    So after a day or so if sunshine I can expect to see my MH control panel reading 13v?
     
  5. Robert Clark

    Robert Clark Funster Life Member

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    It was very cloudy so I'm not sure the panels could have coped with the load.

    My suspicion is that there might be a fault between the solar controllers and the batteries. My logic being that voltage at the output of the solar controller does not prove that the batteries are even connected.
     
  6. Jim

    Jim Ringleader

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    A quick glance at voltage and its easy to think that your bank is charged. However I have a Victron Monitor and use the % to see the actual state of charge.

    My three panel in morning sunshine and I'll have a reading of 13+ volts but check the percentage and I might be only 85% charged

    [​IMG]
     
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  7. Lenny HB

    Lenny HB Funster

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    As you have Gel batteries, as they charge the voltage should go up to 14.2 /14.4 volts then reduce to a maintance charge of 13.8 volts. To fully charge Gel batteries once the reach 14.2/14.4 volts they need to be held at that voltage for 8 hours. It not holding at the higher voltage for sevel hours your charger may not be set to Gel. I would check the voltages with a multimeter as CBE panels tend to read high (on the ones I've seen).

    Blimey how did you get 5,760 watts of solar on the roof.:)
     
  8. Jim

    Jim Ringleader

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    Thats the mistake I used to make. I'd see 13.4 or so on the panel and I'd tell people "My solar panels are fantastic, my Batteries were charged by 8am" The truth is as you say, just because they show that voltage they are not yet charged. My massive battery bank might be fully charged but only if the panels have kept it at that voltage all day :)
     
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  9. Robert Clark

    Robert Clark Funster Life Member

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    How / where is this connected to Jim
     
  10. Robert Clark

    Robert Clark Funster Life Member

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    Hi Lenny
    My concern though is that after a cloudy day the voltage hadn't increased - it was only showing as 12.8 on the MH control panel. As if the solar had not charged at all
     
  11. Jim

    Jim Ringleader

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    Sorry I've no idea, I had it fitted at the same time as my Panels by Vanbitz
     
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  12. Lenny HB

    Lenny HB Funster

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    To answer your question you need to know how much power you have taken out of the batteries (how many amps for how long), the solar was probably just keeping up with your usage. On a cloudy day in the UK you are probably only getting 25% of your panels output about 5.5 amps.
     
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  13. Robert Clark

    Robert Clark Funster Life Member

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    I think I've found the issue!!!!

    My motorhome is pre wired with a cable from the ceiling to the battery (old battery position, as mine were moved to the garage)

    There is a fuse where the cable attaches to the old battery connector
    There are also two connectors near the ceiling, where the solar panels connect to the pre installed cable which leads to the battery.

    I removed the fuse in the battery compartment and tested it - looks fine
    I tested the voltage at one end of the fuse holder (the end nearest the battery) and it read 12v+
    However the voltage at the other end of the fuse holder, leading from the solar panels read 0V

    I then checked the voltage at the connectors which connect the solar panels to the pre wired solar cable - and it read 13+v at the solar side, but 0V at the battery side, which suggests that the pre installed cable leading from the ceiling, where the solar regulators are, to the battery compartment is faulty.

    Would you agree?
     
  14. Lenny HB

    Lenny HB Funster

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    Common practice for dealers to by-pass the built in wiring if you had the panels installed by your supplying dealer god help you. My mate had his done by them, certainly rates as one of the biggest bodges I've ever seen.

    Need to follow the wiring all the way through may be a red herring.
     
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  15. John Laidler

    John Laidler Funster

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    I've just remembered, when we were away our solar stopped charging, fortunately so did the TV. Fortunate, because my MH manual told me which fuse to check for the TV which I found was blown. When I replaced it both the TV and the solar panel started working.

    I hadn't realised the solar controller was connected to the batteries through a 10A fuse but it was - I had simply reused the existing connections when I fitted the Victron controller in place of the previous unit.

    The point of this rambling account is before I replaced the fuse the controller was showing a steady yellow light, which I think is what you have. So a steady light may indicate there is no connection between the controller and your batteries.

    As it was fitted by Eddie VB I am sure they would have installed it properly and there will be a fuse somewhere in the feed to the batteries. Either a standalone fuse or one of the connections in the fuse box.
     
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  16. peterc10

    peterc10 Funster

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    Robert, I have the same controller. It measures net input or output (in Amps and volts) to or from the batteries and from whatever source at any one time and tots it all up to report the state of the batteries. It is connected directly to the battery bank and my display is above the hab door next to the crappy Hymer control panel. Easy enough to fit - the only difficult bit is routing it to where you want the display unit. The dealer fitted mine (including the difficult bit), but I had to re-fit it when I subsequently put in the inverter.

    Pop over and look at it if you like
     
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  17. Robert Clark

    Robert Clark Funster Life Member

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    Thanks for that
    Like you I assumed that yellow solid meant batteries full
    I've ordered a new cable and will run a new feed to the battery tomorrow
    I'm not blaming Eddie for this as he connected to a cable supplied by Carthago.
    I'd just like to prove my theory and start charging my batteries
    Would seem strange that I've had solar for a year, but with no benefit !
     
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  18. matamoros

    matamoros Funster

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    I know absolutely nothing about solar but following your recent blogs you seem to move on every day which i would assume recharges your batteries.
     
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  19. Robert Clark

    Robert Clark Funster Life Member

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    That's exactly what's been happening
    On our last trip, the batteries never went above 12.8v, unless we'd been driving, even though it had been a very sunny day
     
  20. Lenny HB

    Lenny HB Funster

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    If Eddie installed it shouldn't be any problem with the wiring. Carthago use 6mm solar cable I find it hard to beleive there is a problem with it, as it is a double insulated heavy cable unless it has been chaffing against a sharp edge somewhere. Could it be a faulty crimped connector at one end or on the fuseholder?
     
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