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Post by cliveshelton on Nov 18, 2012 12:12:58 GMT
There were a number of things on at the time, including some cabin lights, water pump (tho' not pumping) and the saloon radio.
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Post by cliveshelton on Dec 8, 2012 19:45:47 GMT
All working now. It turns out it was working all the time. However if less than 1amp is being drawn, the ammeter shows nothing. The meter measures to the nearest whole amp and has in indication for 0amps. DOH! As soon as I turned on some stuff (decklights etc) the ammeter showed itself.
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Post by Caxton on Jul 6, 2014 18:48:42 GMT
Hi Trevor,
I have a 2007 SO 39I and installed the shunt and sensing wires. I am getting bizarre Amp readings which I doubt are correct. When I have no DC loads on the reading is 5 amps. When I press the fuel/water level button and the led readout backlight comes on, it shows 20 amps until the backlight goes out and it returns to 5 amps. The fridge appears to be drawing 5-6 amps. To see if I was actually drawing 5 amps with no load, I left everything off (showing 5 amp load on the panel) for two days and my batteries were still at 12.6 volts. The shunt I used was 100A/50mv, is it possible I have a bad shunt or is there something else that could be giving me what appear to be erroneous readings? Thanks in advance.
Caxton
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Post by Trevor on Jul 7, 2014 12:11:28 GMT
Hello Caxton,
Well the SO39i has exactly the same panel as the SO36i so it should work just fine. It does seem strange that the fridge seems to drawing the right amount of current. If the panel shows 5 amps with no load, how did you deduce the fridge load was 5 amps? Did the ammeter actually read 10amps so therefore the fridge had to be 5 amps?
If that is so, the shunt is working correctly and perhaps you really are drawing 5 amps. I am assuming the test where you left the boat for a couple of days with 5 amps on the current meter was not on shore power with a charger.
If you have a reading of 5 amps with no load, what happens if you disconnect the black thick cable from the battery negative to the shunt? Does the 5 amp reading go away?
The backlight causing an apparent 20amp reading indicates the shunt could be different and not a 100amp/50mV specification but let's assume for now it is right. Please check that the electronics panel does have a negative connection to the fuse panel. It would have a negative connection which needs to be checked in case it has come off as it is sounding like that kind of a problem to me.
I know it is annoying when these things don't work properly but with some good detective work the problem will be resolved.
Let's know what you find,
Regards,
Trevor
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Post by abrearle on Jul 7, 2014 17:07:52 GMT
I recently added the shunt and wires to my 2011 36i. I am seeing a similar behaviour.
With no loads running I see 1A on the ammeter display. When I use a DVM to measure the voltage across the shunt at the contacts going into the back of the panel I see 0mV. When the fridge is running I see 4A on the panel display. Using a clamp meter I see the fridge is drawing 3A.
There seems to be an offset of 1A. I need to do some investigation to try and determine what is flowing in the cables.
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Post by Trevor on Jul 8, 2014 13:23:50 GMT
Hello abrearle,
That is strange. If no current is flowing through the shunt, but it still reads something, could the panel earth be slightly offset from the Battery negative for some reason? I understand the panel is reading the differential voltage between the sense wires but perhaps one of those is assumed to be at the battery negative potential and in for some reason the panel earth is slightly offset for some reason?
I assume if the sense wires are removed no current shows on the panel?
Regards,
Trevor
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Post by abrearle on Jul 9, 2014 1:06:24 GMT
Trevor,
Good idea about the potential difference between battery negative and panel earth. I will check to see if there is a difference between them.
I will also try disconnecting the battery negative sense wire and see if the panel still shows a current reading. I.e. with the battery negative sense wire removed the only way the panel can measure a potential difference is if it using a negative from somewhere else on the panel.
Yes, if I disconnect the sense wires, there is no current display.
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Post by Caxton on Jul 9, 2014 15:21:03 GMT
Ok, this is embarrassing! I rechecked everything and I had accidently plugged the upstream sensing wire into the third connection instead of the second! Everything working great now. One weird thing that happened was when I tried to take a flash picture of the working panel; the flash saturated the led screen and blanked it out. Is that normal? I reset the breaker and the panel came back normally.
Geoff was right those connectors are tough to get out. I ended up using a drill to get it out. Thanks for the help guys!
Caxton
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