Ammeter

[adolph santorine]

I’ve been looking to add an ammeter to the house panel.

Most of the meters instructions have the shunt in the negative side of the circuit.

Any reason I could not put it on the positive?

I’m not clear on why they are listing it in the instructions that way.

Thanks.

Dolph Santorine

DE AD0LF

Wheeling, West Virginia

1977 ex-Palm Beach TZE167V100820
Howell EFI/EBL , Reaction Arms, Manny Transmission

 

[mike kilroy]

Probablyl safety. If you put it on negative side and a wire shorts to
chassis, no big deal at all; if you put it on the positive side, a
shorted wire can burn down your coach. As for physics, both work the
same exact way.

> I've been looking to add an ammeter to the house panel.
>
> Most of the meters instructions have the shunt in the negative side of the circuit.
>
> Any reason I could not put it on the positive?
>
> I'm not clear on why they are listing it in the instructions that way.
>
> Thanks.
>
> Dolph Santorine
>
> DE AD0LF
>
> Wheeling, West Virginia
>
> 1977 ex-Palm Beach TZE167V100820
> Howell EFI/EBL , Reaction Arms, Manny Transmission
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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[jim miller]

> I’ve been looking to add an ammeter to the house panel. Most of the meters instructions have the shunt in the negative side of the circuit.


Another approach is to avoid the use of a shunt and instead use one of the snap-around hall-effect current transducers that can give you a 0-5V output proportional to current.

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[tyler]

I agree with the safety/burn down coach threat, as my 1975 apparently just missed burning to the ground at some point prior to my owning it. Full hot,
unfused wire had been run through the firewall to the non-shunt style ammeter below the steering wheel. The evidence I found indicated that something
around the gauge shorted, burning the gauge and a few inches along the wire path/plastic dash. It put itself out apparently once it burned what was
providing the ground. When I discovered it, early in my coach learning curve, I gingerly went out and disconnected that wire (still intact and full 12
volt to the burned mess). Given that history, I'm going to learn more about the hall effect style mentioned by Jim should I ever decide I need one.
--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC

 

[RF_Burns]

The shunt needs to be in the negative line because the electronics measure the voltage drop the shunt with reference to the battery negative. So
there will be a wire that picks up battery negative and positive and the voltage drop across the shunt. The voltage at the shunt's "output" will be
slightly positive with respect to the battery negative when discharging (it will be opposite when charging).

If you put the shunt in the positive line, then the voltage drop will be referenced to the battery positive terminal. If the shunt is just used to
extend the current range of a common series ammeter, it should work fine, proved to keep the ammeter polarity in mine as well.

If the shunt is feeding an electronic ammeter or battery condition monitor, you need to put it where the manufacturer specifies for it to work
properly.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that