ammeter

66mustangg · Mar 18, 2006

I was talking to this guy who owns a wire shop a couple of weeks ago and he was telling me that I really shouldnt hook up my Ammeter gague and I should just get rid of it. he said that all it does is cause problems. does anyone know if thats really true??? b/c i dont know if i should hook mine up now

zookeeper · Mar 18, 2006

I'd be interested in knowing how a guage causes problems. Until recently, all cars had ammeters, yet I don't remember seeing a rash of cars along side the road with broken ammeters. I know the general thinking these days is that voltmeters are a better way to go, and I certainly won't argue that point, but I also wouldn't worry about having an ammeter in my car.

Red5oh · Mar 18, 2006

The problem was the amount of current actually going through the wiring harness and into the interior, etc. Caused heat and almost everyone I have ever tore down... had heat discoloration at the terminals.

It wasnt that recently that they did away with the ampmeter.

Use a volt meter... its simply the best way to go and will cause you less trouble in the future.

mustbereel · Mar 18, 2006

Fire

The amount of current going through the wire to the ammeter is very high. The ammeter on my first Mustang did not work when I bought the car. Wanting everything to work I rewired the ammeter. The first time I turned on the key the wire overheated and melted the insulation. This could easily have started a fire. The wire I used was obviously too small but none of the ammeters have worked in the 3 classic Mustangs I have owned and I haven't tried to fix one since the meltdown. The voltmeter gives you the info you need.

Brad

whwright · Mar 19, 2006

Many factory "ammeters" were actually milli-voltmeters with zero pointing straight up. You can tell this type of meter by the small gauge wires going to it. Usually one lead is connected at the alternator (or voltage regulator) and the other lead is connected at (or near) the battery. When the voltage at the alternator is a little bit higher than the battery the gauge reads "charge" (positive millivolts); when the voltage at the alternator is a little bit lower than the alternator the gauge reads "discharge" (negative millivolts). On the systems I've messed with both wires were fused; if either fuse blows the meter doesn't work, but most people don't even notice. I've never seen one with numbers (that doesn't mean they don't exist); they usually just have "D" for Discharge and "C" for Charge on them.

Most aftermarket ammeters are the real-deal, true ammeters that have to be wired between the alternator and the battery in order to give a meaningful reading. This results in some really big wire. It also means that when the battery is charging or discharging, the entire load is carried through the firewall (probably twice) in order to get through the meter. Lots of times they get wired up without any fuses, meaning there is an unprotected wire (or two) going through the firewall. That's a really good opportunity for a fire.

I don't think ammeters produce very much useful information. In my opinion, a voltmeter is much more useful and tells you a lot more about how the system is functioning.

66Runt · Mar 19, 2006

That is exactly how the "amp" gauge works in a '66.

whwright said:
Many factory "ammeters" were actually milli-voltmeters with zero pointing straight up. You can tell this type of meter by the small gauge wires going to it. Usually one lead is connected at the alternator (or voltage regulator) and the other lead is connected at (or near) the battery. When the voltage at the alternator is a little bit higher than the battery the gauge reads "charge" (positive millivolts); when the voltage at the alternator is a little bit lower than the alternator the gauge reads "discharge" (negative millivolts). On the systems I've messed with both wires were fused; if either fuse blows the meter doesn't work, but most people don't even notice. I've never seen one with numbers (that doesn't mean they don't exist); they usually just have "D" for Discharge and "C" for Charge on them.

Most aftermarket ammeters are the real-deal, true ammeters that have to be wired between the alternator and the battery in order to give a meaningful reading. This results in some really big wire. It also means that when the battery is charging or discharging, the entire load is carried through the firewall (probably twice) in order to get through the meter. Lots of times they get wired up without any fuses, meaning there is an unprotected wire (or two) going through the firewall. That's a really good opportunity for a fire.

I don't think ammeters produce very much useful information. In my opinion, a voltmeter is much more useful and tells you a lot more about how the system is functioning.

I think you hit the nail on the head with your last paragraph.

Scott

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