Re: Volts vs. Amps gauge
Hi - eireton, With an ammeter you see the current flow. Positive for charging, negative for discharging. A voltmeter shows you equivalent information in a different way, but in addition, shows your battery state of charge. All comments below assume good, clean battery circuit connections.<br /><br />If the engine is running and you see 13.5v on the voltmeter, the alternator is working.<br /><br />If the engine is off with a load on the battery, e.g., fishfinder, stereo, etc. on and the voltmeter reads around 12+ volts, you have a good charge. As it gets below 11.5 you will have a starting problem. The voltage under load shows you your battery status, not the amps drawn. The ammeter would show amps drawn which is interesting and useful but abstract infornation and not useable to determine the state of charge of your battery..<br /><br />In addition, with an ammeter, the ammeter has to be in the charging/discharging circuit meaning Large Long Wires to the meter from the battery to the meter. More opportunities for weather to corrode the circuit and degrade your charging circuit. A voltmeter draws virtually no current so a small wire can be used with no effect to the charging/discharging circuit.<br /><br />It's late and I welcome additions/modifications to this post.<br /><br />Regards, Mike