Charging Starter Battery from Hab Battery

Discussion in 'Tech/Mech General' started by Scottyboy, Jan 3, 2014.

  1. Scottyboy

    Scottyboy Funster

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  2. 1Oll

    1Oll Read Only Funster

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  3. Johns_Cross_Motorhomes

    Johns_Cross_Motorhomes Trader - Motorhome & Accessory Sales

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  4. Moodybrook

    Moodybrook Funster

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  5. John Laidler

    John Laidler Funster

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    I don't think so. The fuse would probably blow if the vehicle battery was flat and you connected the habitation batteries to it. The principle is fine but I guess you would want it rated at at least 30A but you would still have to remove it to start the engine.
     
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  6. Moodybrook

    Moodybrook Funster

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    Yes happy with that, so uprate the fuse at huge expense, I guess you might keep a wee supply of fuses. They are meant to blow if you forget and wind up the engine.

    The alternative £59.99 from "Gods" (Jim) shop.

    Not meant for resurrecting a battery but neither would a battery master on its own. You need to take some remedial actions to prevent the "dead battery" scenario. :thumb::Wink:
     
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  7. GJH

    GJH Funster Life Member

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    It's exactly the same as the one on eBay and from Vanbitz so save money and leave eBay out of it :Smile:

    I fitted one of the CAK tanks equivalent devices to our previous van and it worked fine. As a result I ordered one for our son's camper last year only to find that, though advertised as in stock on the CAK web site, it was in fact out of stock and we had to wait some time for delivery. If tempted by CAK tanks, therefore, ring them to see if it is in stock before ordering.

    Our current van has a built in device as part of the Elektroblock and an 80W solar panel but I still plug it in to EHU every few weeks during winter to stop the battery flattening.
     
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  8. Scottyboy

    Scottyboy Funster

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    Didn't realise Jims shop had em, I shall order one in the morning:thumb:
     
  9. pappajohn

    pappajohn Funster Life Member

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    the item in the op's link IS a van bitz battery master Peter.

    Priced at full retail though. £69.95
     
  10. Moodybrook

    Moodybrook Funster

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    Did you look at the link :Doh:

    http://www.motts.dsl.pipex.com/BRIDGING FUSE.htm

    cause I don't believe you would spend money like water if you don't need to. It so simple a solution :Smile:
    For the price of a bit of cable and a fuse block, I'd guess maybe a tenner and the job is sorted. :thumb:
     
  11. pappajohn

    pappajohn Funster Life Member

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    there is a major drawback with that system....it can work backwards too.

    If something discharges your leisure batteries they will draw power from the engine battery so flattening that too.

    And if the fuse isnt removed before starting the engine it will blow....it wont handle the 400 plus amps going to the starter motor.

    A battery master cannot do that...its basicaly a one way valve only feeding cab battery from hab battery
     
  12. Mikeco

    Mikeco Funster

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    I carry a set of heavy duty jump leads which will reach the vehicle battery from the leisure battery .
    When I did park the van up for 4 months last winter when I took the caravan to Spain I connected the two batteries together with a fused cable and the solar panel just charged both up.

    Mike
     
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  13. TheBig1

    TheBig1 Funster Life Member

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    sorry to burst the battery master bubble, but it is only a diode circuit that senses the voltage at the leisure battery and if higher than the preset voltage allows current to flow into the van battery. a simple diode will only pass current in one direction when one side is 0.7volts above the other. so if your leisure battery is charging at 13.8 volts then it will pass current if the van battery falls below 13.1volts.

    im not saying its purely a diode inside the plastic encapsulation, but its not much more. maybe even more likely a power transistor and resistors, but that works on the same principle. what im getting at is the contents costs pennies but putting it in an epoxy plastic lump to hide it makes for a huge markup

    each of these will pass 3Amps so just add more for higher capability. cost 49p each retail
    http://www.maplin.co.uk/p/3a-silicon-rectifier-ql83e

    the most they would cost to make is a couple of pounds each plus a plastic case and sticker

    maybe i should make a few up and sell them for beer tokens?:Rofl1:
     
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  14. Moodybrook

    Moodybrook Funster

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    Yep that is the same thing, It wasn't my idea I just came across it in my search for charging veh batts. :BigGrin:

    Basically it is connecting the veh batts to your leisure batts then your EHU or your Solar panel that feeds in, treats the whole lot as one battery bank.

    Basically this and Battery manager is meant for when the vehicle is laid up or stored for a period and to cope with the stealth attacks mainly on the veh batt.

    Crucial to include a fuse should you forget to disable the connection before starting the engine. Also as pointed out don't connect up if there is a big disparity between the level of charge in the veh batt compared to the leisure batt/s. again there will be a big flow from one to the other, not ideal.

    If all things are equal then pop the fuse in, ( 20A- 69pence, 30A-69 pence midi fuse holder £2.50, 6mm squared £2.70 metre), and Let the solar do the job, or connect to a safe supply, EHU. :thumb::thumb:
     
  15. Terry

    Terry Funster

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    It must be me that looks for the simple method :BigGrin: I simply use a 13 quid Aldi battery charger connected to the vehicle battery and the LB has it's own charger in the rear :thumb: The aldi one lives in the foot-well (wired permanently to VB ) and simply needs plugging into the 240 socket in the van as and when wanted-once she stood for any time and HU cable deployed it's usually on :Wink:
    terry
    edit not exactly charging from LB but it works for me and it's cheap
    THE BIG 1 if you want to make me one of yours (a few quid) I'll give it a try out :Wink:
     
    Last edited: Jan 5, 2014
  16. Moodybrook

    Moodybrook Funster

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    Yep that's good, I have a standby Halfords one. I can't find the split relay jobbie that the Battery master connects to :Doh: a very helpful inmate on this site had been helping me, so looked for an alternative.

    BUT If you have solar ??? and it is sitting outside catching a few rays, even in Winter, even in Scotland, I guess you might get enough to keep up with the stealth drainage, experience will tell me. Waiting on my blooming panel, Xmas has got in the way !! :thumb::thumb:
     
  17. StitchUp

    StitchUp Read Only Funster

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  18. StitchUp

    StitchUp Read Only Funster

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    Question for all you leccy experts out there.

    Ideally, where should one best install a 'battery master'?

    1. Near the leisure batteries?
    2. Near the starter battery?
    3. It doesn't matter?

    Cheers

    John
     
  19. chaser

    chaser Funster

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    That is what I thought , but didn't like to suggest it as thought there must be some reason it didn't work. Seems the simple thing to me, no running one battery down or complicated electronics just plug in and the jobs a good un.
     
  20. Techno

    Techno Funster Life Member

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