Battery Gauge ( Ampmeter ?)
Thread Starter
Melting Slicks
Joined: Mar 2000
Posts: 2,975
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From: Northwest Iowa
Battery Gauge ( Ampmeter ?)
What does everyone's battery gauge (ampmeter - is that the correct terminology) read while running at cruising speed. My gauge reads right about on 0, maybe slightly on the Plus side. Is that normal? I don't recall it running that low before. I thought it was higher than that before.
Recently I took the belt off my AC and had to tighten the Altenator belt and noticed after that that it was reading around 0.
If it is reading around 0 and that's not suppose to be correct, is it a sign that the Altenator is going bad or battery is not holding a charge? In other words, what does the batery gauge measure exactly?
Recently I took the belt off my AC and had to tighten the Altenator belt and noticed after that that it was reading around 0.
If it is reading around 0 and that's not suppose to be correct, is it a sign that the Altenator is going bad or battery is not holding a charge? In other words, what does the batery gauge measure exactly?
Melting Slicks
Joined: Apr 2001
Posts: 3,399
Likes: 279
From: Olmsted Falls, Ohio
Re: Battery Gauge (Rich's75)
When I first start it the needle is higher (+) and then it slowly comes down to slightly more than middle (0+). I believe the scale is in volts therefore it is a Voltmeter that shows the condition of the battery and it's associated charge (in volts not amps). A weak battery can still show 12+V and not start the car....
[Modified by KenSny, 10:58 AM 10/2/2001]
[Modified by KenSny, 11:00 AM 10/2/2001]
[Modified by KenSny, 10:58 AM 10/2/2001]
[Modified by KenSny, 11:00 AM 10/2/2001]
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Re: Battery Gauge (Rich's75)
My Vette doesn't have an Ammeter but my daily driver & one of my Bikes have. If either show anything other than 0 Amps then I start to worry. If it reads negative then current is being drawn from the battery, which will eventually drain it. If the gauge reads above 0 then current is being supplied to the battery, which could be due to the battery being low, or it is being overcharged. Ideally you want the gauge to read a gnats thingy over 0 Amps in normal use with a fully charged battery.
:cheers:
Paul
:cheers:
Paul
Instructor
Joined: Sep 2001
Posts: 171
Likes: 1
From: Rolla MO
Re: Battery Gauge (Rich's75)
I don't know about '75s, but my '71 has an ammeter. Ammeters indicate current - so when you first start your
car the battery discharges a bit from working hard to turn the starter. Thus the ammeter should read
positive, indicating the altenator is charging the battery. As you drive, the needle should drop to near zero
as the battery charges back up. Note if you turn your engine off, and then put your headlights on the
meter will read negative. This tells you the battery is discharging (i.e., powering the lights). This is one
way to tell if your altenator (or its belt) fails while you're driving - the meter will read negative.
If your '75 really has a voltmeter, it should read a constant value, around 13 volts (actually a bit higher...
around 13.4). This value should not change very much as you drive. Engine speed will change
it a little, as will operating electric devices such as your headlights or fan. Your altenator must produce
more than 12 volts (i.e, a little over 13) in order to "push" current into the battery and charge it.
car the battery discharges a bit from working hard to turn the starter. Thus the ammeter should read
positive, indicating the altenator is charging the battery. As you drive, the needle should drop to near zero
as the battery charges back up. Note if you turn your engine off, and then put your headlights on the
meter will read negative. This tells you the battery is discharging (i.e., powering the lights). This is one
way to tell if your altenator (or its belt) fails while you're driving - the meter will read negative.
If your '75 really has a voltmeter, it should read a constant value, around 13 volts (actually a bit higher...
around 13.4). This value should not change very much as you drive. Engine speed will change
it a little, as will operating electric devices such as your headlights or fan. Your altenator must produce
more than 12 volts (i.e, a little over 13) in order to "push" current into the battery and charge it.
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Re: Battery Gauge (UKPaul)
Looks like a couple of replies were posted wile I was typing mine! If the gauge is a Voltmeter then please completely ignore my last reply as it will be completely wrong! An Ammeter normally has 0 in the centre of the scale & charge & discharge currents on either side.
The Voltmeter in mine reads just above 12v without the engine running & something above 14 (ish) with it running.
Paul
The Voltmeter in mine reads just above 12v without the engine running & something above 14 (ish) with it running.
Paul
Thread Starter
Melting Slicks
Joined: Mar 2000
Posts: 2,975
Likes: 1
From: Northwest Iowa
Re: Battery Gauge (UKPaul)
Thanks guys for the clarification. My gauge says on it "battery". I guess it is a ammeter due to the fact that it does have a center marking at 0 and a minus to the left and a plus to the right. My daily driver has a voltmeter, which has 0 to 18 shown the right range from 12 to 14 Volts.
Now, as far as mine reading just above 0, I guess that's alright. Sounds like that is where it's suppose to be.
Again, thanks you guys. It's great to have friends like you guys to ask the stupid questions to and not get laughed right out of the door or get taken advantage of.
[Modified by Rich's75, 9:30 PM 10/2/2001]
Now, as far as mine reading just above 0, I guess that's alright. Sounds like that is where it's suppose to be.
Again, thanks you guys. It's great to have friends like you guys to ask the stupid questions to and not get laughed right out of the door or get taken advantage of.
[Modified by Rich's75, 9:30 PM 10/2/2001]
