Leisure Battery charging efficiency

Discussion in 'The Beginner' started by Vanman, Sep 21, 2016.

  1. Vanman

    Vanman Funster

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    I’m trying to understand which extra’s, if any, I’m going to need to keep my leisure batteries charged. I know that they are topped up when the engine is running, but how does that compare with being on EHU or Solar or a generator.

    So, if my leisure batteries were on 60% which of these would benefit them most to least?


    An hour with the engine running (assuming the cab battery is 100%)
    An hour on EHU
    An hour on 100w Solar panel (on a sunny day)
    An hour on a 2000w Generator


    Thanks
     
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  2. pappajohn

    pappajohn Funster Life Member

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    Engine...waste of time unless you're driving from Wales to John o'groats.
    Once the cab battery is charged the charge current is next to nothing.
    EHU and 2kWh generator....same thing and best of the lot....except the generator is noise and needs fuel.
    100w solar panel....maybe 10 hours of full sun MIGHT charge from 60%.

    The one you missed is a B2B (wrong terminogy ?)charger..... bangs in full alternator power when engine is running regardless of engine battery charge.
     
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  3. TheCaller

    TheCaller Funster

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    Depends on what m/h you have. Some, continental conversions in particular, have more sophisticated 12v charging systems than others as standard.

    Then there are some very new base vehicles with fancy systems to sense the state of charge of the vehicle battery & shut the alternator down as a fuel saving measure. Not all converters have the nouse to turn these off, resulting in almost non-existent leisure battery charging.

    When you say a 2000w gennie, I assume you have one already or need that output for something other than battery charging. Unless you have a very big battery bank & pair it with an expensive high output battery charger, it won't be able to absorb more than about a quarter of that output.
     
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  4. Vanman

    Vanman Funster

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    Ah - I didn't realise that, I thought when the cab battery was full it would continue feeding the next battery.

    OK - good to know

    I'll try and find out more about that (y)
     
  5. Vanman

    Vanman Funster

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    Now that you mention it I have seen on some technical spec. pages that some boast more powerful alternators, but it never quite occurred to me why.

    I have a PC2800LR unused in the garage ... it probably weighs and sounds the same as a steam engine, but if it's only to keep the beer cold on a bike rally field then I may get away with it during daylight hours ...
     
  6. Bobby22

    Bobby22 Funster

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    EHU will charge batteries to full capacity so long as they are n good condition.
    Solar is good for keeping them topped up.

    Running the engine will top them up as well.
    Gennie ....old hat.
     
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  7. Vanman

    Vanman Funster

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    Thanks. I suppose part of the problem is that I already have a Gennie and do not have a solar panel ... and it's likely to be a field somewhere with no EHU and in the UK so there will be no sun ;)

    But it sounds like I need to suck it and see, running the engine of the van when I get it to see if/how quickly it tops up the batteries. If it's as good as a Gennie then it would seem daft to take one, unless it uses loads of diesel in place of the petrol Gennie?
     
  8. Bart

    Bart Funster

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    @Vanman we have one of them B2B chargers , but DO NOT have solar panels , the B2B charger we have is the 60amp version : http://www.simplysplitcharge.co.uk/shop/viewitem.cgi?BBW1260

    For us it charged our 3 x 130 AH batteries no problem when we were away for our 2 week trip to Scotland etc.
    We never touched an EHU once , but all our appliances inc TV are 12v and we never had an inverter fitted then.
    We did drive every day , moving from site to site so this charged the batteries no problem.
    It all depends on what type of holiday you have ,, if you are going to a site and sitting still for a week , a B2B charger would not be any good to you unless you ran the engine / alternator to recharge the batteries.
    If you are like us and like moving around ,, then a b2b is what you need , preferably along with a battery bank.
     
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  9. DanielFord

    DanielFord Funster

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    I feel an experiment coming up to test all of these :D
    However, I would have thought that an hour on EHU and an hour on gennie will be identical, since you are providing 240v to the van. The onboard charger has no idea that it is coming from the national grid, or from a generator!
    When our engine is running, the battery monitor seems to only report a small increase in charge, most of the power is coming in from the panel.
    I can tell you that we managed perfectly OK this weekend using only solar at Lincoln (we have a 150w panel), we weren't frugal with our power the coffee machine was used to death, and we were charging various gadgets throughout the day. We did run out of electricity early this morning, but then the sun came out, and the coffee machine and microwave were back in service.
    Don't forget, even on a cloudy day, the solar does provide a current, just not as strong as on a sunny day. In direct sunlight, we have seen just over 10amps from our panel, on a cloudy, but clear day, we can sometimes get 1amp of charge, that is just enough to keep the batteries topped up, but clearly not enough to replace heavy usage.
     
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