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Volt meter

Discussion in 'TECH/MECH GENERAL' started by hilldweller, Feb 25, 2013.

  1. hilldweller

    hilldweller Funster

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    1 person likes this.
  2. Gromett

    Gromett Funster

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  3. Gromett

    Gromett Funster

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    Last edited: Feb 25, 2013
  4. destination unknown

    destination unknown Funster

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    This is the type we have fitted to the rig. Volt meter via 3 way switch which shows volts from Chassis/Leisure/Leisure (spare)
    Also fitted same design but amp meter via shunt, shows what we are using from leisure.
    Again only a few quid each.
  5. Jim

    Jim Ringleader Staff Member

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    How they can make them, ship them 8000 miles, then the maker, seller and eBay still make money, it beggars belief. :Eeek:
  6. Taran_Las

    Taran_Las Funster

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    I use one of these here
  7. Johns_Cross_Motorhomes

    Johns_Cross_Motorhomes Trader - Motorhome & Accessory Sales

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    You would be very surprised at the cost FOB China Jim !

    Peter
  8. stcyr

    stcyr Funster

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    We've got one of these wired into the solar gubbins... found it very useful in letting us know when to cut down on consumption... :thumb:
  9. motorhomelover

    motorhomelover Banned

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    they must be stolen :Rofl1::Rofl1::Rofl1:
  10. magicsurfbus

    magicsurfbus Funster

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    I've got a couple of those voltmeters that fit into the 12v ciggie lighter sockets - one on the dashboard and one on the leisure battery circuit. Very handy because they're portable.

    What's also useful is the little digital display thermometers with sensor - I fitted one to the MH fridge's front panel. Trouble is the readout in Southern France in August is frightening. We had one day where it didn't go below +16 degrees inside the chiller compartment, although the icebox remained frozen.

    I've also got one fitted on the house fridge so I can see if the lodger's been leaving the fridge door ajar ;-)
  11. bungy

    bungy Funster

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    youll need to use a Isolated DC-DC converter for these, if you use the same source as it is measuring it will probably just short out or just not work at all

    Alternativly take the 12v from the hab battery or vice versa if your measuring the hab battery
  12. Gromett

    Gromett Funster

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    I don't follow you?
  13. bungy

    bungy Funster

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    Basically this amp meter needs a power source which is not directly from the same circuit you are measuring the amps or it won't work or will short out.

    for measuring the hab battery, don't take the power for the meter from the hab battery unless you are using an isolating dc-dc converter.

    Ooops ....just noticed in my previous post I should have typed..alternativley take the 12v from the Van battery or vice versa if you are measuring the van battery
    Last edited: Feb 25, 2013
  14. johnp10

    johnp10 Funster

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    Being able to monitor amps used is obviously useful.
    Battery voltage can be measured at the control panel or with a multi meter.

    At the risk of indulging in muppetry............
    I'm no electrical wizard, so have I got this amps measuring business right?

    I have 2 leisure batteries totalling 185 amps, so I would need a device rated at say 200 amps?

    The shunt would be spliced into the (+) outlet from the leisure batteries to the control panel?

    The power source cant be taken from the leisure batteries?

    Power source from the vehicle battery is ok, as the device would only draw milliamps?
    From fag lighter ok, or hard wired?

    Can a similar bit of kit be spliced into the AC circuitry, or is that unecessary?
    Last edited: Feb 25, 2013
  15. Gromett

    Gromett Funster

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    I still don't follow you. Why should it short? I don't follow your logic.

    The shunt is in series (usually on the negative terminal) then you connect the supply as normal. No short there....

    This is exactly as it should be.:Confused:
  16. Gromett

    Gromett Funster

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    No you just need a shunt that is capable of carrying your usage at maximum. I have 500AH of battery and a 100Amp shunt. Never seen it go above 35 amps when charging and never about 15amp discharging.

    The shunt is usually on the negative terminal. Disconnect everything from the negative terminal of the battery. Connect one side of the shunt to the battery terminal then reconnect everything back to the other side of the shunt.

    You can power the meter from the same battery. Not sure what bungy is on about here but hopefully we will get an answer soon and clear up my confusion:thumb:

    forget the AC side not necessary.
  17. johnp10

    johnp10 Funster

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    Thanks Grommet.
    Sounds easy enough.
    So....that will monitor how many amps being used at any given time?
  18. Gromett

    Gromett Funster

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    And also how quickly you are getting charge in. for instance from a solar panel or main charger.

    It's like a really rudimentary NASA battery monitor without the cumulative count/% left readings..

    Wait for Bungy just in case I am missing something.
  19. bungy

    bungy Funster

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    Im talking about the meter shorting btw .....as most amp meters at the cheap end of the scale dont allow for a common ground between what is being measured and the dc supply that powers the meter. These are also generally used in multimeters etc so generally expect a seperate power supply

    The wiring diagram on the both that are listed show two distinct circuits, one for the shunt and one for the power. So assuming they are correct....they need a seperate supply to what is being measured

    Also need to be aware of where the shunt needs to be for the particular meter, most are designed to be in the - side, to eliminate common mode voltage....which the first one listed is. But some are designed for the + side. The second listing doesn't say which it is so may be worth checking with the seller on both counts to be sure.
  20. Gromett

    Gromett Funster

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    I don't see how a common ground could cause a short. Can you point me at an internal circuit diagram that explains what you mean please?
    Last edited: Feb 26, 2013

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