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  1. #51
    Join Date
    Nov 2001
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    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
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    6,834

    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by GHA View Post
    How it's wired >

    Shouldn't the shunt be in series with tither the positive of negative battery connection not parallel as indicated.

    Is there a hall effect current sensor that can be used in stead of a series shunt that can introduce a volt drop if high currents flow as when using a windlass or bow thruster.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  2. #52
    Join Date
    Jun 2013
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    Hopefully somewhere warm
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    9,188

    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by Rogershaw View Post
    Shouldn't the shunt be in series with tither the positive of negative battery connection not parallel as indicated.
    Not the way it's working here. The INA219 has it's own shunt resister, normally the current goes through that but the way it's wired here the INA is measuring the voltage drop across the main battery monitor shunt resister (down to micro volts) then the current is calculated from that. I thought it was 50mV/100A but the voltage drop * 10,000 is giving accurate amps so must be a 50mV/500A. The INA shunt resister is in parallel with the main one so will be intruding a tiny error, it's a massive value compared to the main shunt resistance so error will be tiny but I'll unsolder it at some point. Surface mount's a bit fiddly!

    Is there a hall effect current sensor that can be used in stead of a series shunt that can introduce a volt drop if high currents flow as when using a windlass or bow thruster.
    The INA is configured for max 40mV at the moment, so should be good up to 400A, plenty I reckon
    Not played with hall effects but there are various available on ebay.

  3. #53
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    Jun 2013
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    Hopefully somewhere warm
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    9,188

    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by vas View Post
    now have you played with any of these cheap touch displays? I mean all these data should really be shown realtime on the chart table .
    Got a nice touch display, called a samsung android tablet

  4. #54
    Join Date
    Jun 2011
    Location
    Volos-Athens
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    4,715

    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by GHA View Post
    Got a nice touch display, called a samsung android tablet
    Oi, that's shifting the goalposts.
    Im sure you have a bt device to view them, I want a fixed one for this. I want it to double as generator start stop and safety stop when temp goes up, add timers etc.

    Does look like the most difficult task I've come across as yet
    V

  5. #55
    Join Date
    Nov 2001
    Location
    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
    Posts
    6,834

    Default Re: DIY ammeter - dead cool

    Yes that how my shunts work.

    On your diagram it looks like one terminal of the external shunt is connected to the positive terminal of the battery via the pirate ship and the other terminal of the shunt is connected to the negative of the battery or am I missing what the pirate ship is doing.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  6. #56
    Join Date
    Jun 2013
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    Hopefully somewhere warm
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    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by Rogershaw View Post
    Yes that how my shunts work.

    On your diagram it looks like one terminal of the external shunt is connected to the positive terminal of the battery via the pirate ship and the other terminal of the shunt is connected to the negative of the battery or am I missing what the pirate ship is doing.
    Not the greatest schematic..

    The pirate ship is the boat, the external shunt is the battery monitor shunt connected in series between the bat neg and everything else- domestic, solar, charger etc, everything goes through there, so any current going in or out of the batteries goes through that shunt. Then the INA219 measures the tiny voltage drop across that shunt and turns it into current. Works surprisingly well.

  7. #57
    Join Date
    Aug 2004
    Posts
    682

    Default Re: DIY ammeter - dead cool

    Is the shunt just for this, or for another battery monitor system? If the latter does it affect the other systems readings?

    Wondering if i can piggy back off my victron bm-702 shunt, without affectinng it?

  8. #58
    Join Date
    Jun 2013
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    Hopefully somewhere warm
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    9,188

    Default Re: DIY ammeter - dead cool

    Quote Originally Posted by gregcope View Post
    Is the shunt just for this, or for another battery monitor system? If the latter does it affect the other systems readings?

    Wondering if i can piggy back off my victron bm-702 shunt, without affectinng it?
    This is piggy backed on a BEP battery monitor shunt. There is a sense resister on the ina219 which should get removed but that should only skew the readings maybe 1% otherwise the 2 seem to work just fine together on the same shunt. Amazing a tiny little cheap sensor from eBay can measure down to microvolts so accurately
    Should be possible to get the esp to serve a Web page with the data either on an existing network or on a network it runs.

  9. #59
    Join Date
    Nov 2001
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    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
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    6,834

    Default Re: DIY ammeter - dead cool

    I have a similar shunt setup for my solar charging setups with shunts 100mV per 100 A feeding a 1999 DVM. My 2 main batteries banks and engine start battery also used to have shunts but changed it to a hall effect setup due to the high current drawn by my bow thruster. The shunts caused a larger then acceptable volt drop across the shunt.

    Your system is great as it allows the current flow to be recorded over time for greater info and control.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  10. #60
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    Jun 2013
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    Default Re: DIY ammeter - dead cool

    This might make a bit more sense about how it's wired >

    Last edited by GHA; 01-09-18 at 12:01.

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