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Thread: Current detection

  1. #1
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    Current detection

    Is there a device out there that can read amp draw and voltage that I can attach to my distribution block?
    Better yet, is there something like that for a computer that would feed the info through usb?

  2. #2
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    Hi
    Something like this ?
    http://www.ebay.com.au/itm/100V-100A...item2a1b8daeda
    If the above link wont work search for 180850896602 on ebay should bring it up
    Last edited by Wozza; 11-15-2012 at 07:24 PM.

  3. #3
    Maximum Bitrate Mickz's Avatar
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    If you want something to measure DC current with very low insertion loss and accuracy then something like this is ideal.
    http://littlebirdelectronics.com/pro...rier-30-to-30a

    You could interface this with a small micro with an ADC input and send data via USB, however an interface app may be needed, a Fusion Brain will do this and may already have an interface for some FE's?
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  4. #4
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    Thanks, the first one looks great because I need it to hit at least 90 amps. However, I dont see how these are any good or safe. If I'm drawing that much current the wires that attach to this would go up in flames. I need a minimum 4G wire for my amp.

  5. #5
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    Quote Originally Posted by Champak View Post
    Thanks, the first one looks great because I need it to hit at least 90 amps. However, I dont see how these are any good or safe. If I'm drawing that much current the wires that attach to this would go up in flames. I need a minimum 4G wire for my amp.
    It uses a shunt for amp measurements ....I only have basic electric knowledge but you can read up on it here http://en.wikipedia.org/wiki/Shunt_%28electrical%29 ....the "Use in current measuring" section
    Last edited by Wozza; 11-15-2012 at 08:16 PM.

  6. #6
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    thanks that will work perfectly. I wonder why more companies don't make sense like this. seems like this would have a fair amount of d
    demand.

  7. #7
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    Did you check out this device?

    http://store.mp3car.com/50A_Current_...74&Click=29952

    It is "only" 50A but it is cheap and you could try it out and see how it goes.
    (If you are going to spend hundreds of dollars on an amplifier then $20 is damn cheap... This device is designed to plug into a fusion brain but could be used with any small microprocessor if your able to build one.)

    How is your system setup?

    Do you have 1 big amp for the subs and then 1 for the rest with other equipment?

    If so then I would use one of these on just the Sub amp and one on the rest of the system.

    If you have multiple sub amps then you might be best served running one of these on each of your subs and one on the combined rest of your system. Or some combination that keeps them separate.

    Plus it might be nice to know how much your sub amps are pulling as compared to everything else...

    You also have to make sure the shunt system you are using is for DC 12 volt and not AC.

    Rodney

  8. #8
    Raw Wave
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    I'd avoid shunts entirely, except perhaps if using existing cables as many "remote shunt" vehicle ammeters do - eg, measuring the voltage drop across a ground or +12V wire.

    I suggest a loop sensor. I've been intending to get some $20 Tamuras from DigiKey for a while - see digikey - Sensors, Transducers > Current or digikey's master Sensors, Transducers > Current listing.

    You'll have to consider how you want to read the output because that determines their voltage supply.
    Though the +5V supply is easiest, it means an output whose zero is centered at 2.5V. That's not a problem if feeding a PC etc.
    But since I wanted to feed normal digital displays (ie, a voltmeter panel), I decided to use the +/-15V versions since their zero (Amps) is 0V and the voltmeter displays whether it's a +ve or -ve flow.


    However, I would question WHY you want to measure current. IMO it is useless for normal situations.
    "To see if my alternator is keeping up" etc is not a valid reason. In fact the ammeter will not tell you how or if your system is coping - the voltmeter does that.
    It can tell you how much the battery is supplying when your alternator is falling short, but why do that? Again, the voltmeter gives a better indication. (A digital display will jump about. And to log the sensor's continuous output and try to match outgoing AH less incoming AH (less ~30% inefficiency on a good battery) is essentially useless, else requires very complicated algorithms etc - ie, what is the REAL capacity of your battery? Again, a voltmeter gives the best indication.)

    I investigate many aspects of vehicle electrical performance yet I rarely use a ammeter. When required - eg, to test what my starter motor consumes - I use a DMM and a $10 50A shunt (but ONLY for a SHORT period of time before it melts!. For lower loads, just the 10A range on my DMM.
    My proposed Tamuras are to do multipoint measurements, but even that is mere curiosity or for experimental stuff.

    Just consider why you want to measure current. If it's curiosity then fine. But if it's for anything else, it's likely not to be the solution.
    Last edited by OldSpark; 11-17-2012 at 09:40 PM.

  9. #9
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    For me it is to generally monitor what the load of what I've installed is drawing at any given time....and can't really overlook the "cool factor". Your solution with the sensors seems ideal, especially connecting it to the computer, but I wouldn't know where to begin to get the computer to read that. Funny enough, I was actually looking for a reay made solution to o exactly that but couldn't find one. But it seems like even the one on ebay wont be of help because it needs 24v, so I would also have to get some type of regulator I believe. It does say 5v optional but I dont know what that would mean with this thing (I guess that means it can feed a computer but i'm a little confused since it comes with the display).

    So it's not really to see if my alternator is keeping up, more to see how much current my stuff is pulling.

  10. #10
    Raw Wave
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    Oh well, I'd question why you want to know what it draws. It's like - who cares?
    And once a typical reading has been taken, you probably know all you need to know. As for amps, you know their max draw and that they'll take 1/4 that current at 1/2 the volume etc.
    Many loads can be calculated from their rating - eg, headlamps etc.
    But I have seen digital ammeters - not that I recall where. Maybe from UK site (mcgillmotorsports) that had plasma display gauges.

    A 3-digit voltmeter is IMO as cool, but is also useful unlike an ammeter. Mine's a blue LED type, about $10 off eBay.

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