Author Topic: Hooking up DC Amp gauge  (Read 3982 times)

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Shadow

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Hooking up DC Amp gauge
« on: June 09, 2005, 10:42:13 PM »
I was hooking up digital amp meter(0-30 amp DC/Shunt) Also a 0-200 volt digital meter. Both require 5 volt power supply.I have a 5 volt out-put regulator. So hooked up a 9 volt battery through a switch to 5 volt regulator, run shared positve wire and shared ground to both meters. So far so good, both lit up,switch activated both. Then installed 30 amp shunt in-line one positive side of incoming DC from Turbine. Hooked amp meter, one lead to each end of shunt. Hooked Volt meter, positive wire to one end of shunt, negative wire to negative DC wire from turbine. I should back up a step I tried volt meter first, When hooked to battery string it showed 49.6 volts,so I knew that worked. I disconnected leads to battery bank, hooked amp meter leads to shunt, reconnected battery leads and poof! a spark, no amp meter and seconds later no volt meter! What happened? It was disconnected from Wind Turbine at the time so no incoming current, only current it could have read was from the batteries.So if I understand this right it should have showed no amps as no current was flowing. Do I need a diode to just read current going to batteries?..or does it matter?.. Lost again..
« Last Edit: June 09, 2005, 10:42:13 PM by (unknown) »

wpowokal

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Re: Hooking up DC Amp gauge
« Reply #1 on: June 09, 2005, 06:44:36 PM »
Shadow I am having trouble drawing out what you describe, however 2 things come to mind.


  1. The shunt should be in the negative lead.
  2. Most/some digital metres can not share the same power supply as that being measured, herein may lie the cause of escaping magic smoke.


allan
« Last Edit: June 09, 2005, 06:44:36 PM by (unknown) »
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Shadow

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Re: Hooking up DC Amp gauge
« Reply #2 on: June 09, 2005, 09:17:12 PM »
I'm not sure I follow you, The gauge has its own 5 volt power supply, seperate from what its measureing. Here is a link to the wiring diagram I followed.To me it still appears to be on the positive side. I dont understand why they show a positive and negative symbol on the meter when you are connecting in series across a shunt.  ?

http://www.lightobject.com/support/PMeter.htm
« Last Edit: June 09, 2005, 09:17:12 PM by (unknown) »

wooferhound

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Re: Hooking up DC Amp gauge
« Reply #3 on: June 09, 2005, 09:40:37 PM »
You did'nt switch your meter to AMPS did you? Your meter will be a dead short on that setting.
« Last Edit: June 09, 2005, 09:40:37 PM by (unknown) »

commanda

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Re: Hooking up DC Amp gauge
« Reply #4 on: June 09, 2005, 09:44:18 PM »
I think you need to use 2 x 9 volt batteries & 2 x 5 volt regulators; one seperate supply for each meter.


I dont understand why they show a positive and negative symbol on the meter when you are connecting in series across a shunt.  ?

So charge current shows as positive, and discharge current shows as negative.


Amanda

« Last Edit: June 09, 2005, 09:44:18 PM by (unknown) »

Shadow

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Re: Hooking up DC Amp gauge
« Reply #5 on: June 09, 2005, 09:56:47 PM »
When I ordered the digital gauges I inquired if one regulator would run two gauges, and was informed it would. If I check the input at each gauge its 5volts going into each one.I was told any power source over 7 volts feeding the regulator was adequate.  AS for the positive and negative, its still hooked in series right? positive going in one end of the shunt and positive coming out the other end? or Negative if on neagitive side.So by connecting one wire to each end of the shunt you are essentially hooking positive to positive with an amp gauge in between, correct?
« Last Edit: June 09, 2005, 09:56:47 PM by (unknown) »

wpowokal

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Re: Hooking up DC Amp gauge
« Reply #6 on: June 09, 2005, 10:53:24 PM »
Shadow the current metre is in paralell with the shunt, a moot point since you followed the diagram but if it was put in series then magic smoke escapes.


If the metre is to share the same power source, as it apears it can, then the shunt must be in the negative lead.


The reason for this is the metre is typically 0-199mv, and ground is the reference point. The voltage drop across the shunt is somewhere between 0 volts and in your case probally 30mv.


Placing it in the positive lead when sharing the same power cource causes it to see full battery volts, not the mv it requires. Been there done that.


The diagram looks very Chinese to me.

allan

« Last Edit: June 09, 2005, 10:53:24 PM by (unknown) »
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drdongle

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Re: Hooking up DC Amp gauge
« Reply #7 on: June 10, 2005, 05:09:27 AM »
I suspect that with both meters sharing a power source there was a low R path through both meters to the battery, and hence the smoke. I'll bet there is/ was a path from battery - through the voltmeter, the voltmeters common lead (-) to the amp meters common lead which is connected to one side of the shunt and battery +.

If he opened up the volt meter he would find a burned common (-) trace, It might be reparable.
« Last Edit: June 10, 2005, 05:09:27 AM by (unknown) »

Shadow

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Re: Hooking up DC Amp gauge
« Reply #8 on: June 10, 2005, 07:43:52 AM »
 Ok, Thanks all, I will return these. I'll get two new ones, with two separate power supplys and try that. I'll hook the amp gauge in the negative side this time.
« Last Edit: June 10, 2005, 07:43:52 AM by (unknown) »

scrounger

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Re: Hooking up DC Amp gauge
« Reply #9 on: June 11, 2005, 02:14:50 AM »
I have some of these units and they seem to share a common ground so if you used the shunt on the Positive side it may have seen ALL of the battery potential (For a brief time).  I use one of the voltage regulators for BOTH the amp meter and the volt meter from a SEPERATE supply so as to NOT affect the measurements.  Also note that these need to be calibrated to be accurate.  The ones that I purchased were 20% or more off until I calibrated with a DMM.  Now they work good.  


Note when I was testing these one of the Neg side came loose, but it still worked due to the sharing of the negative ground.


Good luck and do the adjustments to get them close.  They really arn't that accurate, but will give you an idea of what is going on.


Skip

« Last Edit: June 11, 2005, 02:14:50 AM by (unknown) »