Volt amp gauge query

[MEGOMONSTER]

I understand the reason for having a volt meter for your batteries but what does the amps meter tell you ( apart from amps) and why we need to know

[threedogs]

Just flickers when blinkers are on or using power, brother in law Auto lec, says never fit amp guage as they tend to catch fire IHO, Volts will tell you all you need to know

[BillsGU]

The latest amp gauges (I have an autron built into the dual volt meter) are all hall effect devices - which means that you DO NOT have huge cables running through the fire wall and under the dash. This means no fire hazzard and simple to install (your borther in law needs to get up with technology). They tell you how much current is going into and out of the battery. To most people this does not mean much and I agree that the volt meter is a more simple way of checking the status of the battery and the charging system. For me, the ammeter indicates anomolies or changes from the norm - which to me indicate that something is not normal and needs to be looked at.

[threedogs]

WAS a while ago I must admit, but wouldn't a volt guage let you know if charging or not

[adventurepaul]

You may have a case where the alternator is ok and putting out the normal 13.8v and steady but the battery is taking a 100 amp charge( not for long that is, as would soon melt) but you get the idea. Amp gauge is really the proper way of indicating load in or out of batteries, a light does the same as a voltmeter in that shows the alternator either on or off. In my game (aircraft) we have dual lights, batts, volts,amps and split bus.

[the evil twin]

Voltmeters tell you with engine off - state of charge of the Battery BUT ONLY if the battery has been returned to resting state.

Voltmeters tell you with engine running - alternator voltage output. The Battery can be almost totally shagged and the voltmeter will read OK

Ammeters tell you the load on the electrical circuits and the net effect to the Battery IE charge/discharge.

The ideal setup is too have both, voltmeters are simple and cheap, older style ammeters depending on technology can be expensive and/or difficult to install which is why they went out of favour with manufacturers.

[BillsGU]

older style ammeters depending on technology can be expensive and/or difficult to install which is why they went out of favour with manufacturers.

Too true! Thats why the latest hall effect meters are so good. You just disconnect one of the battery leads (usually the negative lead), insert the lead into the hall effect ring, reconnect the battery lead, and roberts your fathers brother!! Its done.

[CptClinac]

The Voltmeter will only tell you the end steps of the battery charge graph. If it's below 12 it's flat. If it's above 14.4 it's cooked. You can make some guesses about the bits between.
A bit like not having a fuel guage on your truck. You know when it's full or empty, and estimate the rest.
A guideline is... at idle your voltage should be above 12, at driving speeds it should be 12.5-13.5. If you turn your headlights on it should still be 12.5-13.5.
This will prove your charging system is working well.

The Ampmeter will prove that the charging system is capable of handling the electrical loads of your truck (including battery charging). It won't be able to tell you if you are overcharging your battery.

My old Austin A40 (those were the days) had neither. You don't normally need them. But don't be tricked into thinking they tell you more than they do.

Dave