Power systems and batteries

Discussion in 'Motorhome Accessories' started by OddSocks, Apr 13, 2014.

  1. OddSocks

    OddSocks Read Only Funster

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    Hi!

    I have been investigating the power systems in my MH.

    I am new to the van, but from what I can tell, having read the blurb, the 'car' battery is wired to the leisure battery via a switch so the leisure battery will be charged whilst driving so long as the 'car' battery is full. The solar panel goes directly to the leisure battery and keeps it topped up so long as it is sunny. What happens if it is sunny while I am driving is anyone s guess! lol

    I can also flick a switch on the control panel to chose which of the two is charged up when I am plugged in to a power supply.

    Just thinking that a lot of my camping is likely to be off the beaten track. So I will rely heavily on the solar panels to keep the battery topped up.

    I know nothing about my solar panel, I can find no documentation for it in the blurb that came with the van. Is there any way of finding out what it is rated at?

    If I add a second leisure battery can I add a second trip switch so that when the first one is full the second one will start getting charge? Would it be an issue having three batteries in a row with two switches like that?

    Or should I just put the two leisure batteries in parallel? Would they both then charge in the same way just as though they were one big battery?

    Thanks for any help :)
     
  2. PaulyP

    PaulyP Funster

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    There are much more experienced people who will answer this question but as i understand putting an extra battery (or 2) in parallel will result in all of them being charged one after each other.
    What you need to know is the solar panel size and if it's up to the job.

    But i may be totally wrong, i will be organising soon to go to Dave Newell and have a solar panel fitted and hope Dave can explain simply how my system works, there seems to be wires around the engine battery that i dont know where they come from.
     
  3. TheBig1

    TheBig1 Funster Life Member

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    sorry but it should be a relay, not a switch that allows power from the alternator to charge the leisure battery. if you add a second or third battery to the leisure battery bank, you are just increasing the total storage capacity measured in amp hours Ah. as they are wired in parallel, positives connected together and negatives together, they will all charge together

    the solar panel will continue to charge the battery as you drive, until the charge controller detects they are fully charged. no simple way to see what solar panel is fitted other than climb up and have a look. measuring the current being supplied by the panel/s will give a rough indication. but this will be affected by a few variables like age of panels, sunlight, any shadows and how clean the panels are

    to be self sufficient, you really need to have at least 80watts per 100ah battery in the bank. and new batteries will be more efficient than old ones. if adding batteries, try to keep them the same type and size. plus avoid connecting new batteries to an old one as if the old one fails, it can kill the new batteries quickly. always fuse each link between batteries to protect them and if a cable between batteries has any risk of shorting out over a long length, then fuse both ends near the terminals.
     
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  4. funflair

    funflair Funster Life Member

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    Hi

    You should be able to make a decent guess at the capacity of your solar panel from measuring the size and comparing to new ones on offer, your will be older and less efficient so match yours to one slightly smaller.

    Martin
     
  5. Techno

    Techno Funster Life Member

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    It's more likely that the solar regulator will go into float mode as it will read the voltage from the alternator and think the batteries are full.
     
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  6. OddSocks

    OddSocks Read Only Funster

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    Hi all,

    Thought a good option would be to post a photo of the panel. Took it from the bedroom window lol

    P4140002.jpg

    I'll drive the van out into the sunshine later. I can borrow a multimeter from dad, but what do I set it to to measure the output? I understand measuring volts (IE Batteries etc) but not Amps.

    There is a controller for this by the drivers cab and I can see the terminals so access is easy. Any help would be appreciated! :)
     
  7. TheDogMan

    TheDogMan Funster

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    Looking at mine on the roof and yours look to be about 120 watts, I have 2 x 120 watts and have 3 hi spec fast charge batteries wired in parallel, yesterday we ran the 700 watt microwave through an inverter for 24 minutes and had the TV on as well, the sun was out and the batteries only went down to 12.6 amp on the display and went back up to 13.4 very quickly afterwards, good batteries and enough of them are the key. I have learnt my lesson with batteries a lot of the leisure ones are crap

    Dave
     
  8. Chockswahay

    Chockswahay Funster

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    Really? :Blush: You would need 60 amps to replace that amount of power (plus extra for inefficiency in the conversion)

    When a battery is either on load or charging the 'meter' will not show an accurate figure for quite a while afterwards. Also you need to have the solar panels off line to take a battery reading.

    The only really accurate way to measure the volts is to take a reading sometime after the event (I have 10 mins in mind but think it might be more like a couple of hours, I am sure someone else will advise:Blush:)

    I do admit that I don't have solar and might be speaking out of turn……sorry

    :Smile:
     
  9. OddSocks

    OddSocks Read Only Funster

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    I can't read my dids little tester. It is one with a needle on it. Not a digital readout like I am used to.

    I disconnected the panels from the regulator, set the dial on the meter to 50 DCv and the needle swung round to something like 75 on the V+mA scale that goes up to 250. Or just under 20 on the V+mA scale which goes up to 50.

    I don't know what any of this means? lol
     
  10. TheDogMan

    TheDogMan Funster

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    Yea really, 700w microwave, 3 ready meals 8 minutes each, 3 x Optima batteries which are the most efficient on the market for absorbing charge quickly also instead of having a rapid decline hold there output at a higher rate for longer, they have cylindrical mats instead of flat ones.
    I should add that having learnt a lesson I ensure that I turn the fridge freezer off auto to gas first as the inverter is linked to the mains circuit and having the fridge freezer on the invertor as well give did me problems with overtaxing the invertor
     

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    Last edited: Apr 14, 2014
  11. pappajohn

    pappajohn Funster Life Member

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    to read amps you need to select amps on the meter and connect the wires to the amp terminals/sockets on the meter, you cant read amps on a volts scale.......and you will need a 0 to 10amp range but it appears your meter only has milliamp ranges mA (one milli-amp = one thousandth of one amp....250milli-amp = 1/4 of one amp.
    So, connecting that meter properly will burn out the moving coil in milliseconds.
    To read amps you must remove the positive lead from the battery and connect the meter between the removed lead and the battery positive terminal
     
    Last edited: Apr 14, 2014
  12. cmcardle75

    cmcardle75 Read Only Funster

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    My advice with multimeters is to never use any current/mA/A range unless you know what you are doing. Stick to volts. You can work out most things you need to know with those. I've got a degree in Electronic Engineering and have used the amp range on my multitudinous multi-meters about 5 times and even then they have rarely given much useful information, but provided many a spark.
     
  13. OddSocks

    OddSocks Read Only Funster

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    Thanks guys!

    So - I figured out the scale on the meter. I was getting 17 volts. Does this tell us anything useful?
     
  14. pappajohn

    pappajohn Funster Life Member

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    if that was from the disconnected solar panel wires then that is normal for most panels and doesnt really tell much other than its working ok.

    If it was from the disconnected battery then the meter is useless and inaccurate..
     
  15. Reallyretired

    Reallyretired Funster

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    I would guess from your picture that it is probably a 80 or 100w panel. Measuring the open circuit voltage as you did will not show you anything I'm afraid.
    You will need to know the current being output.Is there no display on the regulator?
     
  16. aba

    aba

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    Normally near where the wires com off the underside of the panel there will be a sticker that will give its info you may need a mirror or a camera to see it.
     
  17. OddSocks

    OddSocks Read Only Funster

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    That was measured across the 2 wires coming from the panel, having disconnected them from the controller first.

    The only display on the controller is a green light that flashes when the battery is full (I read about this by googling the sunsie (I think it was) controller.) Quote:
    [ As the charging starts for the day and battery state
    of charge is low, charging will be
    continuous and the “CHARGING”
    light will be on all the time. Battery
    will be charged up to 14.5V, the
    Boost voltage, and kept at this level
    for two hours using PWM control.
    Then, the controller goes into float
    mode and will maintain the battery at
    13.7V indefinitely as long as the load
    current does not surpass the charging
    current.]
    I don't know what PWM is but it seems to flash at two different rates once the battery is full and I am assuming that it relates to the two different states (PWM and Float mode) mentioned above.



    I will borrow a ladder and get up and have a look tomorrow and see what I can see. Thanks for the hint! :)

    At then end of the day the only way to know where I am is to suck it and see. We are planning a jaunt up to North Devon later in the week, assuming I get the parts I need to fix the starting problem (I have been promised they will arrive on Wednesday) So we will find out then exactly what is what. I guess at the end of the day I all I need to know is if I have enough power there for everything I need to do. And there is only one way to find out huh? lol

    Thank you so much everyone for taking the time to give me advice on this issue! :) :thumb::thumb:
     
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