Leisure Batteries Questions

Discussion in 'Motorhome Chat' started by mdixon, Aug 27, 2013.

  1. mdixon

    mdixon Read Only Funster

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    OK

    My leisure Battery has died and I am wondering what the best solution is.

    We have electric bikes that need 240V charging
    We use the Telly and Lights

    Am I right in assuming that for the charging of the bikes we will need to be on hook up most of the time? Or is there an inverter solution that is practical?

    What rating on the battery do you suggest for Value for money.?
    Would I be better buying 2 batteries and linking them in parallel?

    What do ye say about these new solar pv panels?

    Please help me out - I am confused:cry:
     
  2. bernardfeay

    bernardfeay Read Only Funster

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    Not my area but I suspect trying to run bike batteries is well over the top. I don't think solar panels would help either.
     
  3. Ber090

    Ber090 Funster Life Member

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    :thumb:Hi, We run a 150w solar panel that charges 2x110amp 12v batteries. We have 2 inverters- 1 does 300w and the other 600w. The bosses electric bike (I still have to use my legs and try and keep up--- revenge she calls it!) is charged by the 600w inverter. In good weather when off grid we have both batteries full by the time we get up. We can use as much as we like during the day and are still ok.
    Hope this helps.
    Cheers
    Bernie
     
  4. bigfoot

    bigfoot Funster

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    There is a school of thought that leisure batteries are more efficient if they are composed of 6 volt batteries connected in series parallel.
     
  5. hilldweller

    hilldweller Funster Life Member

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    Sounds like an old wife's tail to me.

    All batteries ( it's the meaning of the word ) are 2V cells connected in series.

    So 6V is 3 cells in a box and 12V is the same cells but 6 in a box.

    What does make sense is the difference between standard batteries, deep discharge batteries and traction batteries. All going up in quality of construction.
     
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  6. mdixon

    mdixon Read Only Funster

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    Can you explain (in stupids langauge) what the difference is?
     
  7. hilldweller

    hilldweller Funster Life Member

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    First get the biggest battery that will fit. 110Ah is probably the figure. Search on here for suggested makes. These posts often point to ebay and £80 or so.

    The BIG question is how does your leisure battery get charged ? By driving, by EHU ?

    The bottom line is, if you don't put more back than you take out it goes flat. That could mean 5 hours driving. It could mean 8h on hook up.

    Solar - very variable, a 100W panel will put back less than 5A on average so that's about two days to recharge, which means if the battery will not last 2 days normal use the solar is only a part solution.

    An electric bike battery could take half of a 100Ah battery to charge it. You've got think where the replacement electricity of that is coming from.

    We use a 300W inverter to charge our electric bikes when not on EHU. It's a juggling act then to see if the 100W solar tops up in time or we have to drive or use EHU.

    So ! Get a new battery, check it's being charged properly or it may not last long. Get a 300W or so inverter ( pure sine way is the best ). Then suck it and see.

    I've recently fitted 100W solar for under £200 off ebay. Our two bikes total 80Ah ( I've fitted big batteries ) so if we cycle a lot it's not going to cope on it's own. It's suck it and see time for me.
     
  8. hilldweller

    hilldweller Funster Life Member

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    There's nothing stupid about this, just skills you've not got yet.

    Batteries can be built in different ways, like the thickness of the lead plates and what supports the plates. Lead is expensive so cheap batteries will have less and will wear out quicker. If you see 2 batteries, buy the heavier one.

    A traction battery, for fork lift truck is about top of the pile, loads of lead to stand a lot of work. A starter battery is the bottom, all it has to do is crank an engine for a few seconds.

    Normally, and very confusing, you should only discharge a battery to 50% so that 110Ah battery has only 55Ah available. A deep discharge one can go a bit further ( not sure how much ).

    So to put some numbers on the, 55Ah and a 12V battery ( which is flat at 12V and full at 12.5V ) has 55 * 12 = 660 watt hours. So you can now get a feel of the problem. Your 60W laptop or TV could last 11 hours. On together then 5 hours. Women demand hair dryers, 2000W, so down a few minutes.

    A electric bike battery could be 360 watt hours, that's half of all your electricity.

    And LED light, about 0.5A but the old incandescent lamp 5A.

    Any clearer ?
     
  9. cmcardle75

    cmcardle75 Read Only Funster

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    Is isn't about quality. It is about the construction of the plates. Some are thin to get a good surface area, which gives the ability to charge and discharge quickly. (These are starter batteries). Some are thick, which makes them less fragile to deep discharge (These are traction batteries). It is a compromise. You can't have a fast charge/discharge battery that can cope with deep discharge.

    The ideal battery for habitation is a traction type battery. It doesn't really matter if they are 2x6V in series or 12V. However, it is much more expensive to make a traction battery.

    "Leisure" batteries are just large starter batteries named to sound like they have some special feature. However, they are so much cheaper than a traction battery, they are still a good choice if you are not full-timing and price is an issue.

    Gel batteries are starter batteries that have gel instead of liquid. This doubles the price just to reduce the chance of spillage, which is minimal anyway.

    Sealed batteries are ones where the case is sealed. This reduces the charge rate, as the hydrogen has to be recombined within the case, so the hydrogen production rate has to be reduced. Avoid, unless your battery is stored inside the habitation compartment of your van.

    If you want to run your electric bikes off solar, you'll need plenty of panels. However, it is probably feasible, especially in summer, if you've got enough roof space to mount them all. If you want to charge at night, make sure your habitation batteries have about quadruple the capacity of your total bike capacity.

    A typical example of the sort of calculations you should do:

    A typical 36V 15Ah bike battery is the equivalent of 45Ah at 12V. These are full discharge Li-Ion. You want to charge two of these overnight.

    At 12V, you'll need to provide 90Ah of 12V electric from your batteries. This will require a 180Ah battery (50% max discharge) just for the bikes. I would recommend using two of these batteries. Each 180Ah battery would cost around £150 if a leisure type.

    Now your solar system will need to supply 90Ah of energy each day, PLUS whatever you need to run your van. If you have LED lighting and don't sit around watching TV all day, you might use 40Ah per day. So the solar has to supply around 130Ah per day.

    You can probably expect a 100W panel to supply about 50Ah per day on a reasonable summer day. So 300W will just about be enough. However, you might find it falls short in spring, autumn or stormy weather (although I guess you won't ride the bikes in the rain...).

    However, if you could squeeze five 100W panels on the roof, you'll be pretty reliable except in really bad weather.
     
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  10. Ed Excel

    Ed Excel Funster

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    Take a closer look at solar pv. Typical efficiencies are 15-18% for pv in its different forms. So, at best you can expect 18W out of a 100W rated panel. On a long summer's day, with 18hrs of daylight, you could generate 27Ahr.
     
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  11. mdixon

    mdixon Read Only Funster

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    It all becomes clearer - Perhaps I only half charge the wifes bike, that will leave me more energy to run!

    Thanks for that:thumb:
     
  12. pappajohn

    pappajohn Funster Life Member

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    2 x 6v batteries can have a far higher capacity for a similar size to a single 12v battery.

    while they are much deeper, though shorter and narrower, than a 12v battery a Trojan deep cycle 6v battery can be as much as 435 ah

    i have a stack of 2v (single cell) batteries rated at 110ah each....only problem, to connect them together as 4 x 12v batteries they weight 504kg......and would still only give me 440ah :Doh:
     
    Last edited: Aug 27, 2013
  13. cmcardle75

    cmcardle75 Read Only Funster

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    The panels are rated after the 18% has already been accounted for. However, they do assume bright sunlight hitting perpendicularly.

    In bright sunshine, mounted horizontally in the UK in August, I get about 60W from mine, nominally 100W.
     
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  14. Ed Excel

    Ed Excel Funster

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    I'm still not clear on the installed efficiency of these things. About the most sunshine hours we get in the UK is 1888hrs. Over 365 days that's 5.2hrs avg. So, taking your max. output of 60W (60/12)=5A. That would produce an average of 26Ahr, round about 15% efficient, unless I'm missing something? Of course if the cells are only used in the summer one would assume improved figures.
     
  15. cmcardle75

    cmcardle75 Read Only Funster

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    The 18% efficiency is about how much of the sunlight they convert to electricity. This is relatively constant for a particular panel, affected by only a few things such as temperature and the appropriateness of the electrical connection.

    The other factor is how much light it will see over the course of a day. It isn't going to be pointed directly at the sun for 24 hours, so lots of factors, such as orientation, weather, latitude and season affect how much it produces. It may be in some cases that these factors might be around 15% of the 24h full sun figure. However, this most definitely isn't a constant, can be very variable, and has nothing to doing with the efficiency of a particular panel.

    However, the possible closeness of the figures in some circumstances similar to that often found by holidaymakers in the UK could cause confusion. A 100W panel is one that produces 100W of electrical output under certain prescribed conditions (basically pointing directly at the sun well above the horizon with no cloud). If it happened to be 18% efficient, it is because it is receiving 555W of solar energy when doing so. The difference between a 15% efficient 100W panel and a 20% efficient 100W panel is that the 20% panel will be physically smaller.
     
  16. MikeandCarolyn

    MikeandCarolyn Read Only Funster

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    Your set-up is similar to ours (2x80w solar and 2x110 batts)
    I'd be interested to know 2 things.
    1,State of bicycle batt. when you put it on charge.
    2.State of your leisure Batts in morn.
    On a normal evening our leisure batts are around 70% by bedtime,so I wonder how much further down charging a bike batt. on a 600W invertor would take them.

    Mike
     
  17. mdixon

    mdixon Read Only Funster

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    OK Gents
    See if I have understood this all properly

    Usage with eveything on My MH - mixture of LED lights and not.......

    V*A=W







    Watts A V No
    Total
    Lights 10 0.833333 12 11
    9.166666667
    Lights 1.5 0.125 12 3
    0.375








    Fridge 130 10.83333 12 1
    10.83333333
    Bike
    10 24 2
    40
    TV 35 2.916667 12 1
    2.916666667


















    Bike Battery Charge
    Hour 1
    63.29166667 A/H



    Hour 1+
    23.29166667 A/H























    Total Battery 260AH Useable 130
    After 1 Hour 43.41666667













    Hrs Left 1.864042934

    Is This correct?

    If so - now all I have to do is the old Apollo 13 Trick of turning off until I get the required time between charges!!!

    Is this really how simple it should be????

    PS Thanks to all that knew this and took the time to tell me - if its right of course:BigGrin:
     
  18. mdixon

    mdixon Read Only Funster

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    PLease ignore - The formatting has gone to pot...

    V*A=W
    Watts A V No Total
    Lights 10 0.833333 12 11 9.166666667
    Lights 1.5 0.125 12 3 0.375
    Fridge 130 10.83333 12 1 10.83333333
    Bike 10 24 2 40
    TV 35 2.916667 12 1 2.916666667

    Bike Battery Charge Hour 1 63.29166667 A/H
    Hour 1+ 23.29166667 A/H

    Total Battery 260AH Useable 130 After 1 Hour 43.41666667
    Hrs Left 1.864042934

    After this it is the old Apollo 13 trick of turning things off until the correct amount of time between charges is met!!!:BigGrin:

    Apologies for the rubbish format of the post above
     
  19. hilldweller

    hilldweller Funster Life Member

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    Third time lucky ??

    You can't format in this editor, it's rubbish.

    But you seem to be on the right lines, I think.
     
  20. Ed Excel

    Ed Excel Funster

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    You didn't mention a fridge in your OP, do you really need to include it? If it is run off the inverter you can reduce your estimate for it by half, because it won't be taking juice all the time.
     
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