voltmeter/ammeter

[sonus]

I have a 1984 Volvo 200D with both an ammeter and voltmeter on the dash.Everything seems to be charging o.k.with 13.2 to 14 volts, depending on RPM,on both the voltmeter and on the multi-tester on the battery terminals.However the ammeter is always reading on the negative side,and when I turn on any accecories it dips even lower.What does this mean and whats the difference between a voltmeter and an ammeter? Do I just have a faulty meter and if so how do I check? I have 2 new, high quality batteries. Thanks for any info.

 

[rodbolt]

Re: voltmeter/ammeter

hello<br /> the ammeter is wired in series with the load and the voltmeter is in parralell. all the current flowing in the entire system must flow through the ammeter for proper operation. thats why they fell out of favor. as boats needed more current meters got to heavy and added more connections(corrosion points) on the power feed.<br /> usually somewher on an old boats life someone will add a wire for something and provide a parralel circuit for the ammeter rendering it useless. if the volt meter shows above battery voltage it shows the system is working. a working ammeter will show how many amps the altenator is putting out or if its not then how many amps the load is using from the battery. to test you will need to remove it and wire it in series with a load. when the load is applied it should read negative. then hook it in series with your batt charger and turn it on. as current flows into the batt it will swing on the positive side.

 

[Don S]

Re: voltmeter/ammeter

Depending on where the ammeter is installed in your electrical system, it may not be able to show the batteries are being charged. It could be setup to show how many amps are being drawn from the batteries by the accesories but not able to see the charge going in.

 

[sonus]

Re: voltmeter/ammeter

Thanks for the reply Rodbolt and Don S.I have a better understanding of the system but I'm not too comfortable playing with the wiring to test something that seems to be working.Think I'll leave well enough alone and just check the voltage at the batteries with the meter once in a while to make sure its charging.Thanks again to both of you for the quick primer on electrical 101.

 

[Don S]

Re: voltmeter/ammeter

You can look at your voltmeter on the dash to see if it's charging.<br />When you turn the ignition to the run possition, you will see around 12.5 volts. When you start your engine, it should increase to 14 volts. That tells you it's charging.

 

[Scaaty]

Re: voltmeter/ammeter

I prefer a voltmeter over a ammeter given the choice..........when the voltmeter don't move, head to shore!