A search yielded little on this subject.... I'm curious whether or not anyone has wired up an Autometer volt guage to accept volt readings from two different batteries. Meaning, on toggle switch A- Battery 1 would report its volts, on toggle switch B- Battery 2 would report its volts, on C the volt meter would be off (and or wiring to the ignition- eliminating the C position). If anyone has done this please let me know. Just curious about how you've wired it.

Thanks.

Go to page seven of this PDF:
http://www.bluesea.com/Instruction/8732.pdf

Interesting. So, I'll have to run some type of relay in order to get the configuration to work? I was hoping for something more simple, like positive off battery 1 running to switch port A, positive off battery 2 running to switch port B. Switch is grounded, and then has an output which would run to the autometer. Guess that won't work. Man, I thought for sure I saw a switch like that a radio shack onetime.

What was the web site for Mechanic Man? Or should I say, where do you order your electrical gear? (relays, wiring, etc.)

I didn't see any relay needed:confused: :confused:

This one is all ready to go! It will check 3 batts by flipping the built in switch

http://www.bluesea.com/catalog_.pdf/meters/pg_33.pdf

Ya you could easily do that you just need a double throw switch it will have three prongs the middle one will go to the gauge and the outside two go to each battery. If you want it to turn off you will need the same switch but it will have to be momentary both directions so you would have to hold it in each direction, instead of just switching it, to get a read for the batteries.

Forgive me then, but what is the "shunt" in the setup picture on page 7? Is that just a zoomed in view of the back of the voltmeter?

Also, I was looking for a solution to use with an autometer guage. While a digitial readout would be nice, that thing is 4X5 inches! A little bit large for trying to find a place to put it inside a truck on the console. The marine quality of the item makes it attractive though. I'd still like to find a wiring solution for a switch.

Again, sounds dumb, but you know in Apollo 13 when they check the battery volts. All they do it rotate a switch and the battery in question outputs to the volt meter. That's all I'm looking for. So I need a switch with an A, B, OFF... I guess.

:shaking: :shaking: I guess you need to be spoon feed! :rolleyes: :rolleyes: I guess looking around the blue sea page is beyond you!:flipoff2:

from the blue sea page!

How a shunt works


Shunts work because they produce a relatively fixed resistance with respect to temperature. That is, for a given amperage flowing through it a shunt will produce a known voltage drop that is, for practical purposes, independent of temperature.

The proportion of voltage drop to amperage is known as the shunt's "ratio". This is expressed as by such notations as 50mV/50A, meaning that with 50 Amperes flowing through the shunt there will be a voltage potential of 50 millivolts between the shunt's two terminals. At 25 Amperes there will be 25 millivolts of potential. Essentially, the shunt becomes a small battery that powers the low resistance circuit of the meter. In many Blue Sea Systems' meters this resistance is 50 Ohms, hence, using Ohm's law (V=I/R), the equation for the meter circuit is 50mv = X / 50Ohms or X = 1 milliampere, the current flowing in the meter circuit.

The amperage side of the shunt ratio is also the rating for the amperage at which the shunt can operate without overheating.


The shunt normally has two separate screws on to which the sense leads are attached. It is important to realize that the integrity of these connections are critical to accurate measurement and should not be used as current carrying connections.

The water pipe analogy below can sometimes help to visualize the princicple on which a shunt works.

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Spoon feeding helps yes. :)
Thanks.