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07-23-2017, 09:27 AM
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#1
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Senior Member
Name: BARNEY
Trailer: CASITA
Georgia
Posts: 125
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Elec. Systems grounding
The dumb question is the one that goes unasked!! Working with '89 cassie, 16' with solar, inverter, 3 100ah batteries and lastly shenzhen bayite tech #pzem-051 multi-meter. The bayite wiring diagram calls for ground wire from load to go to shunt for reading. Am i correct to thimp that "load" would be "house" useage as lights, radio & coffee and not include trailer running, stop, turn lites
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07-23-2017, 07:15 PM
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#2
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Senior Member
Name: Elliott
Trailer: Bigfoot
Everywhere
Posts: 462
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The shunt goes between one side of the battery and "everything else" including all loads or sources. If electrons flow in or out of the battery without passing through the shunt, the meter won't be accurate.
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07-23-2017, 09:06 PM
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#3
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Senior Member
Trailer: Oliver
Posts: 713
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Quote:
Originally Posted by Defenestrator
The shunt goes between one side of the battery and "everything else" including all loads or sources. If electrons flow in or out of the battery without passing through the shunt, the meter won't be accurate.
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The Negative side...
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Steve and Tali - Dogs: Rocky and our beloved Reacher, Storm, Maggie and Lucy (waiting at the Rainbow Bridge)
2008 Outlaw Oliver Legacy Elite & 2014 Outlaw Oliver Legacy Elite II
2022 Silverado High Country 3500HD Diesel 4x4
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07-23-2017, 10:13 PM
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#4
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Senior Member
Name: Elliott
Trailer: Bigfoot
Everywhere
Posts: 462
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Usually, yeah. By convention rather than requirement, though, so probably better to go with "the side specified by the instructions for that meter, usually on the ground side, which is usually negative".
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07-23-2017, 10:57 PM
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#5
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Senior Member
Trailer: Oliver
Posts: 713
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Quote:
Originally Posted by Defenestrator
Usually, yeah. By convention rather than requirement, though, so probably better to go with "the side specified by the instructions for that meter, usually on the ground side, which is usually negative".
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You are correct about "convention rather than requirement". But there's a compelling reason to use the negative/ground side as opposed to the positive...
__________________
Steve and Tali - Dogs: Rocky and our beloved Reacher, Storm, Maggie and Lucy (waiting at the Rainbow Bridge)
2008 Outlaw Oliver Legacy Elite & 2014 Outlaw Oliver Legacy Elite II
2022 Silverado High Country 3500HD Diesel 4x4
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07-24-2017, 12:59 AM
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#6
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Senior Member
Trailer: Scamp
Posts: 7,056
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Quote:
Originally Posted by Steve Outlaw
You are correct about "convention rather than requirement". But there's a compelling reason to use the negative/ground side as opposed to the positive...
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What is this compelling reason????
According Kerchoff's law it doesn't matter.
__________________
Byron & Anne enjoying the everyday Saturday thing.
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07-24-2017, 01:31 AM
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#7
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Senior Member
Name: Elliott
Trailer: Bigfoot
Everywhere
Posts: 462
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Safety, sort of. Since the shunt is a big hunk of (often exposed) metal, it's easy for it to short against something else. Assuming negative ground (true for any major vehicle from the past few decades), putting the shunt on the negative side means contacting ground will just make your metering inaccurate instead of causing a dead short of the batteries. You could probably also just put the shunt in some sort of enclosure and be about as safe, but there's no reason not to put it on the "ground" side.
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07-24-2017, 10:44 AM
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#8
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Senior Member
Name: Steve
Trailer: Scamp 13
California
Posts: 1,889
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My view is: in DC circuits electrons flow from Negative to positive so the meter goes first between battery negative and the distribution network. It measures the consumption of energy so you have to know what is flowing through the meter. If put on the positive side, power would be consumed before the meter got a chance to see it.
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07-24-2017, 11:10 AM
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#9
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Senior Member
Name: J Ronald
Trailer: Casita 17 ft. Liberty Deluxe
North Carolina
Posts: 236
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Current flowing from negative to pos post should always be the same current. All current that leaves the negative post will and must be the same that enters the positime terminal it is not possible for any to fall off in transit.
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