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Ammeter/Voltmeter Option


rob864_0

Member
Joined
Oct 28, 2020
Messages
18
City
Pasco, WA
Vehicle Year
1986
Transmission
Automatic
My 86 BII is now operating a 4.0L from a 91 Explorer. What is best solution to charging indicator. Wire up to existing ammeter OR remove shunt on ammeter to make it function as a voltmeter?
Thanks for comments.
Rob
 
Myself I did put in an ammeter however I did not hook it up, it is only for show. didn't want the amps going into the dash and becoming a fire hazard. just wire in a voltmeter and that will be fine. there is no way you want to try and use an amp meter as a volt meter. wont work.
 
I second the motion, wire in a voltmeter and forget running all that amperage through the dash. It didn't make a lot of sense when generators and alternators made 40 amps, it's hazardous now.
 
Its only maybe 6 amps thru an amp meter, so less than main headlight switch :)

But in any case a Volt meter with Battery Light is easier, which is what car makers switched to theses

A "shunt", in this case, is just a SLIGHTLY smaller gauge wire on the B+ wire that runs from alternator to Battery positive
The amp meter's, 2 small wires, are hooked to either end of shunt, like a by-pass wire
So maybe 5% to 8% of the amps generated by alternator pass thru the Amp Meter

Digital volt meter is the best to use, it can be hooked to ANY key on 12volt wire in the cab, very little voltage draw
These have numerical read out so you can see right away if alternator is not working as it should, so No Battery Light needed

Yes, if you do away with amp meter then remove Shunt, because without amp meter hooked up full amps can't go to vehicle system, 5% to 8% are bottle necked by the shunt wire size



Shunt for water
Say you have a 2" water pipe
You put a section of 1.5" pipe in the middle
And put a section of 0.5" pipe run next to the 1.5" pipe
Because of the reduction in size of the 2" pipe to 1.5" that would force some water thru the 0.5" pipe
The 0.5" pipe is the Shunt
And you can deduce the amount of water flowing, and the direction of the water from the shunt

Direction flow in Amp Meter shows as Charge or Discharge
And some Amp meters are calibrated, so they can accurately show the Amps, i.e. 5, 10, 15, 20, 25, ect.....amps
Most vehicle Amp meters are not calibrated, lol, they may have lines and numbers but only the C or D really matter
 
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In other words head loss is directionally proportional to length and inversely proportional to diameter!
 

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