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amp meter

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I agree with Greg and Keoke,
If you are considering buying and then adding a gauge to use to
monitor your car's electrical system, a volt meter is a better choice for the reasons mentioned by Greg and Keoke.
If you already have an ammeter, Greg showed the best way to
hook it up.
A voltmeter is a good indication of the overall " health" of your car's electrical system.
That Smith's voltmeter that Moss sells looks like an exact match for the BJ8 black gauges and it is lighted ( just install the same LED as discussed in Roger's LED upgrade and then it will be a perfect match ). You don't have to run heavy gauge wires through the firewall to hook up a voltmeter. Just connect one wire of the voltmeter to one of the green switched wires that is
only on when the ignition is on. The other wire goes to ground. Attach the light wire to the string of other dash light wires ( red and white ).
Done.
 
Ed_K said:
Just connect one wire of the voltmeter to the big brown wire that feeds the light switch and the other wire to ground.
Click to expand...
The one thing I'd suggest is to hook the hot lead of the voltmeter to either a white wire (and add a fuse), or tap into a green wire. That way, if the car sits for months, there won't be a drain on the battery.
 
Another vote for voltmeter.

I'm also not a fan of ampmeters; I don't want to have the entire electrical current of the car flowing behind the dashboard.

Not that British cars are prone to electrical problems...
 
Greg,
You are right about that. That is a better way to connect. To a switched hot lead like one of the green wires instead of the big brown wire. I was thinking about where the best place would be to sample the system voltage. I forgot about the non switched aspect of the big brown wire. Thanks for keeping me honest.....
I edited the original post with the green wire instead of the brown.
Ed
 
Well a volt meter will tell you that and not introduce a potentially catastrophic failure mode into the car's electrical system. It looks like every one likes Voltmeter I love it when a plan comes all together--Keoke :laugh:
 
Keoke, why would an amp meter cause a potential catastrophic failure? It is only diverts a single brown wire. It goes through the fire wall like the browns to the ignition switch and head light switch. Where is the additional risk? Would an inline fuse reduce any risk?
 
tahoe healey said:
Keoke, why would an amp meter cause a potential catastrophic failure? It is only diverts a single brown wire. It goes through the fire wall like the browns to the ignition switch and head light switch. Where is the additional risk? Would an inline fuse reduce any risk?
Click to expand...
Ampmeters are basically a cheap instrument; I've seen them fail "open" resulting in nothing working (until you land both wires on one terminal of the gauge), and also seen the results of them internally shorting to ground = NOT pretty.

In my opinion, they're a disaster in kit form, only needing a few ingredients to come to a full bloom.
 
Tahoe Healey,
I have an old Stewart Warner gauge that was in the car when I got it in 1981. I just bought a cheap one to test out my overdrive solenoid and thought about replacing the old SW gauge. I know that Randy knows what he is talking about and will drop that idea. I trust the SW gauge, but not the $20 one made in China. If you decide to proceed with an ammeter, get a high quality one and an inline fuse may be a good idea to protect against the short to ground fault, but of course won't protect against the open fault. The in-line fuse would have to be similar to the 50amp UK spec fuse that came standard. A U.S. equivalent would be 25-30 amps. You could install it between the brown wire and the gauge wire.
 
The amp meter is installed and all is well. Its very cool to see what is going on while driving since the battery is 8+ years old. (I already have a volt meter). I know many of you are not fans of amp meters but its fused with all new wire. Thanks to all.
 
Triumph TRs used an ammeter, I know all the juice in the system goes through them, but I have driven TRs for many years and know others that have as well with no problems with the guage or the wiring associated with it.

I never felt compelled to add one to my 100, but did like the immediate notification of charge/discharge state that it gives, lets you know if your generator can keep up with everything with lights, wipers, etc. on at night, or if the voltage regulator or generator has gone off on you pretty much immediately.
 
Am I missing something or is there some reason nobody has mentioned a shunted amp meter? You can mount the shunt anywhere you like and just have a small current going through the meter itself. If the meter fails, the shunt is still carrying 99.9 percent of the load and you just go on without an amp meter. They are specifically used so you can have an amp meter without the vast majority of the current actually going to the gage. I'm thinking about putting test jacks in the cockpit, perhaps in the glove tray area, so I can plug in a digital volt/ amp meter and use it when I drive, or take it out to keep things primitive. I'd put the shunt on the firewall.
 
Jon, you are not missing anything, but may be overestimating the electical IQ of some of us (in my case pretty easy to do)....
 
It is hard for me to under-estimate the collective knowledge of the folks who post here. It seems rare that I know something that you all might not. Truly glad to be of occasional service.
 
There are a couple reasons I didn't mention shunted ammeters. Main one is I don't think you could get one that matched the existing gauges unless you had someone make it custom. Another issue is heat. The shunt (resistor) can be overloaded with less current the hotter it gets. Doubling the current quadruples the heat. Healey engine compartments are pretty hot so there is a possibility of burning the shunt out if you're running a lot of current through it. Then all the current goes through the thin wire to the ammeter gauge.
 
Well it does not make much difference whether you use a shunt type ammeter or not. Installation of an AMP introduces a fatal single point failure into the car's electrical system.--Keoke
 
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