If the 12v distribution panel and the batteriers (2-6v) are about 25' apart and connected by #2 wire, how accurate will this meter be if connected at the panel instead of the batteries? The goal is to monitor battery voltage when using the inverter, and charging voltage when plugged to shore power. I am thinking of wiring in a switch so I can turn off the display completely at night.
Why not find out??
Take the meter and check voltage at the batteries.....then check when you hook up at the panel. You will see if there is a difference, and can figure that in to any calculations you might make regarding the batteries.
My guess, you won't see but maybe 0.1 volt difference, which isn't really much to worry about.
Bill & Claudia / DD Jenn / DS Chris / GS MJ Dogs: Sophie, Abby, Brandy, Kahlie, Annie, Maggie, Tugger & Beau RIP: Cookie, Foxy & Gidget @ Rainbow Bridge.
2000 Winnebago "Minnie" 31C, Ford V-10
Purchased April 2008 FMCA# F407293 The Pets
If the goal is to monitor battery voltage then you get an inline fuse holder, put a 1 amp (or smaller) fuse in it (down to around a quarter amp I'd guess) and hook it to the POSITIVE battery post, extend it out to the POSITIVE terminal on the volt meter) Negative wire runs from the volt meter back to the batteries, NOT the chassis, NOTE: put the fuse in last.
If you wish a switch in the line,, Well, ok, no problem.. Just put the fuse in last.
If you connect anywhere else you will get false readings (either high or low depending on what's happening just now)
Both leads back the the battery, FUSE in the positive as close to battery as possible, The meter should not need more than a quarter amp but blade fuses are the easiest and finding fractional amp is hard so use a 1 amp.
Nothin adds excitment like something that is none of your business
Kenwood TS-2000 housed in a 2005 Damon Intruder 377
For the most accurate measurement at a remote location you are absolutely correct.
In the trades this is called "four terminal monitoring" from the special shunts used for monitoring high currents without long runs of big wire. This is an example of four terminal current shunts.
The heavy, current carrying conductors are fastened to the studs, and the sensing conductors are fastened to the small sampling screws.
This prevents the resistance of the high current connections from causing errors in the monitoring circuits.
Similar techniques are used for remote voltage monitoring with the sensing connections not directly connected to the high current terminals to avoid the effect on the measurement by voltage drop across the connections.
For the direct monitoring of the battery, the sensing wires should be connected directly to the battery lugs, independently from the current carrying conductors. I have seen this done by drilling and tapping a sensing screw into the battery post. I have looked but I did not find a photo that showed this type of connection. I hope the description is adequate.