What do a shunt do , anyway ?

CA Traveler wrote:
Here's my 500A shunt. It's not recommended to install a shunt like this near flooded batteries.

While "not recommended to install a shunt like this near flooded batteries" a shunt needs to be a close as reasonably possible to the battery. Keep it clean (Baking soda bath a couple times a year) and coated with some kind of grease/oil (lanolin grease/oil like Fluid Film) and it will last forever, even mounted on top of a flooded lead acid battery.

WOW , I am the OP , I guess that I should just follow the directions on the meter that I ain't bought yet !

The environment of a switchboard room is considerably friendlier than the bay of an RV.
Yes I am fussy

Yes I will disassemble a shunt. Resize the holes for SAE fasteners
Screw in SILICON BRONZE studs then silver solder the back side of the shunt. S/B flat washers, lock washers and nuts.

Apply a drop of DeOxit beneath the milli amp wires
Or for my own use SOLDER the milliamp wires direct to the blocks.

Then assemble with silicone dielectric grease.

For me it pays off. Absolute dead-on accuracy for decades.

(Got better things to do than rush an important work just in time to run in the house and catch "Judge Judy".

wanderingbob wrote:
I was looking at a meter and it said shunt required , Why ?

And after all of those replies.............
Assuming that you were looking at a multi-function meter:

It will function just fine for all of it's functions EXCEPT reading high currents, for which an external shunt is required.

Typically, that means volts, ohms and amps up to 10 just with the meter itself.

And....you can't just get any old shunt. You need one with a resistance value that matches the meter calibration.
If you want to read high currents, that is.

Duplicate deleted.

deltabravo wrote:

MEXICOWANDERER wrote:


Never a good idea to stack cables on a shunt, use....

I stack cables on the shunt all the time.

I used to work for a company that sold amp hour meters, and we never told people not to stack multiple cables on a shunt.

It’s ok to stack terminals if some thought goes into it.
The higher amp terminal should be on the bottom and size matters. You want to minimize high current transitions between terminals.

DrewE wrote:
For smaller currents, there are actual analog DC ammeters that don't measure the voltage across a shunt. They have a coil driving the meter that's wound with a few turns of heavy wire, and respond to the magnetic field that's directly proportional to the current. (Indeed, analog voltmeters are arguably really ammeters as well, as it's the current through the coil in the meter that drives the movement.)

I thought it was an internal shunt. Learn something new every day.

MEXICOWANDERER wrote:


Never a good idea to stack cables on a shunt, use....

I stack cables on the shunt all the time.

I used to work for a company that sold amp hour meters, and we never told people not to stack multiple cables on a shunt.

ScottG wrote:

My professor liked to ask his unwitting class how many types of meters there are. His answer was one; the volt meter.
The amp meter is actually a volt meter with different markings.

With a shunt type meter, that's pretty much true.

For smaller currents, there are actual analog DC ammeters that don't measure the voltage across a shunt. They have a coil driving the meter that's wound with a few turns of heavy wire, and respond to the magnetic field that's directly proportional to the current. (Indeed, analog voltmeters are arguably really ammeters as well, as it's the current through the coil in the meter that drives the movement.)