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I am installing an aftermarket ammeter and questioning how/where I should attach the wires. The instructions that came with the gage are not specific other than warning not to connect it directly to the battery. Any suggestions?
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Don't, ammeters are an unneccesary fire hazard. Use a volt gauge instead.
--
69 142S Overdrive + 69 164S Manual
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Paul;
Sorry...I cant agree with you on that because it's just not true...Ampmeters with their heavy gauge, direct Battery connection if haphazardly installed, with wires running over sharp sheet-metal edges certainly would be, but so would a poorly installed Voltmeter be...fact is that properly installed Ampmeters are no more a fire hazard than any other powered wire...like for instance, the heavy gauge, direct Battery connected wire supplying the Ignition Switch...and every car has one of those!
See also: http://www.sw-em.com/elecramb.htm#additional
Cheers
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A voltmeter, properly installed, won't burn you car down because it is protected by a fuse. An ammeter can set your car on fire because it has no protection. Also, an ammeter doesn't tell you anything useful because of it's crude scale, while a voltmeter tells you exactly what's going on.
"fact is that properly installed Ampmeters are no more a fire hazard than any other powered wire...like for instance, the heavy gauge, direct Battery connected wire supplying the Ignition Switch...and every car has one of those!"
I'd describe the unprotected heavy gauge wires in old cars as neccessary evils. Your logic is to increase the risk of electrical fire for a completely useless amp gauge. Also, why haven't fitted a fuse to your ignition supply?!? (And your headlights)
I have seen 1st hand what happens when ammeter wiring sets a wiring harness and dashboard on fire in a 40tonne forklift because I had to fix the mess! When a $850,000 machine is down losing thousands of dollars per hour in productivity due to a $20 vanity gauge, it seems fairly rediculous. I can tell you I put a voltmeter in and removed a completely unnecessary source of fire.
--
69 142S Overdrive + 69 164S Manual
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Paul;
We'll have to agree to disagree on this one...
"an ammeter doesn't tell you anything useful because of it's crude scale, while a voltmeter tells you exactly what's going on."
I feel the exact opposite...a Voltmeter (even one with expanded scale) gives system voltage which is pulled up and down by a number of factors (and again, 0% to 100% Battery charge happens within 0.8V...talk about a "crude scale")...an Amp meter gives magnitude of current, and whether it's flowing into or out of the Battery, and THAT is what I'm interested in!
...hopefully we can also agree that EITHER meter, with proper interpretation is head and shoulders better than an idiot light only!
Cheers
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I wouldn't knock the idiot light. In a driving situation it tells you the most important thing: you might have just thrown a fan belt and are about to cook your engine. You could quite likely notice the light but I doubt if you'd notice either the ammeter or the volt meter being on the wrong side of charging. On my rally Volvo, I replaced the idiot light with a bigger brighter one in the middle of the dash for exactly that reason.
I understand the good reasons for an ammeter, but if I'm driving and the voltmeter shows above 13v, that's good enough for me.
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JohnH, Sydney, Australia
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I've owned something like 18 cars over 45 years (not counting parts cars), and I don't remember any of them having an ammeter or voltmeter. This is the one case where I think an idiot light tells you all you need to know while driving. If it does show a problem, it's time to get out the multimeter and find out what the trouble is, but I don't need to have a meter installed in the dash.
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Your experience just happens to exclude those disabling faults which are not reported by the idiot light, depending on the technology employed at the time. Otherwise you would not say it "tells you all you need to know."
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Art Benstein near Baltimore
What engineers say and what they mean by it:
"Extensive effort is being applied on a fresh approach to the problem"
We just hired three new guys; we'll let them kick it around for a while.
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Please give me an example of a disabling fault the light would fail to report (other than the light itself being burnt out, which would cause a fault only in a "B circuit" charging system). ???
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Name the car you're asking about. Which of the eighteen?
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Art Benstein near Baltimore
What engineers say and what they mean by it:
"The entire concept will have to be abandoned"
The only guy who understood the thing quit.
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Okay, Phil, perhaps your ??? was rhetorical, but part of me was thinking you might ask about a car within the thread's roundfender topic and challenge my recollection of the voltage regulators used with DC generators. I think I could write scenarios where the ammeter might have prevented a roadside service, but none would be from my actual experience.
The experience which leads me to claim the idiot light is not foolproof comes to me most memorably with Bosch EL and my 240s. I've had 17 cars and none came with anything more informative than an idiot light. I recall some did not even have a temperature gauge. With the exception of one Chrysler product, to which I added a voltmeter in pursuit of an intermittent, the non-Volvos in my past gave me no reason to doubt the usefulness of the warning lamp.
However, the Volvos, one by one, had voltmeters added. In one, while chasing a temperature sensitive stator short in an 80A Bosch, I temporarily added an ammeter. Before doing that, I was not sure the battery wasn't having one cell shorting. Anyone else would have swapped parts to figure this out.
The problem with this idiot light, and really all of them, is its value so depends on taking inventory at key on, before starting, during lamp test. Do I do this? As anal and analytical as I am known to be, I don't. Although doing so will not guarantee the lamp warns you of failure once driving, most of the real world faults would be caught. Examples are the very common vibration caused failure in the ground wire at the alternator, or simply oxidation at the D+ (61) terminal.
But, when you are driving happily down a country road and wonder why the radio is starting to sound mushy and cut out, it could be too late to shut off all the loads, use the parking brake to avoid brake lights, and find out how long the spark will continue and the fuel will pump and squirt on 10 volts and dropping. No red lights. Remembering the $320 spent on an alternator in another town. Looking for the nearest place to buy a battery.
If I did not have those experiences, the idiot lamp would have told me all I needed to know. I think the best solution given my experiences would be a battery voltage monitor with alarm, giving an audible warning if the system voltage is ever below 13 after 10 seconds of engine run. It would not need to have a dashboard presence beyond perhaps a flashing idiot light to remind me what that noise was telling me. The voltmeters are just easy, whether they are a decor-matching instrument or a $6 cigar lighter plugin.
--
Art Benstein near Baltimore
"He's the best mechanic in town." - 1992 Annemarie Powell said of General Colin L. Powell, a Volvodad
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You're right that a failure in the D+ circuit would not show up on an idiot light, although I have never seen that problem on any of my cars, my customers' cars, or any other car I've driven. I'm not trying to be confrontational, just saying that an ammeter is of very limited usefulness at best.
I've seen plenty of ammeters in British cars (of a certain age, at least), some of which didn't even have fuel gauges. I don't recall seeing one in any Italian or German car. Volvo didn't see fit to have them, even in the 1800 series, which are otherwise fully instrumented (oil temp as well as oil pressure). I don't suppose Ferrari omitted ammeters because they were trying to be cheap.
I remember a voltmeter in an early-'70s Firebird Formula, maybe just because it was cool to have lots of gauges, and that was a cheap one to add.
OTOH, I've seen lots of charging problems that the light warns of. Total failure (blown rectifier diode, for instance)is a bright light, of course. Worn brushes give a dim light. DF failure gives a light that brightens as revs increase.
I actually had one car come in with a charging problem that turned out to be due to loose connections at the added ammeter. And of course the gauge itself could fail internally and cause lack of charging without telling you anything about it.
It's fine with me if anyone wants to install an ammeter, although I think a volt meter is potentially more useful (as in the case of a shorted battery cell -- you'd see that right away). I'm just saying that for me, personally, either one is w-a-y down the list of instruments I'd want to have.
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D+ failure would show up as no warning light when you turn the key on.
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69 142S Overdrive + 69 164S Manual
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Teams:
Bernstein/Kwas
VS.
Paul/Singher
First team to calculate PI to its final value wins...BEGIN!
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That's more of an individual pursuit. You go first Kwas.
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Granted, an idiot light tells you most of what you need. It tells you whether the battery is charging or discharging, just not how much (other than the difference between a faint glow and full brightness). Ammeters were common in the 1950s but were replaced by idiot lights and voltmeters to cut costs.
--
1992 745, >500k km
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John;
I have no problem with enunciator lights to immediately draw attention to an abnormal condition...after that, we would look to gauges (if we had them!) for more specific info...
I even wired an obnoxiously loud beeper on a T fitting in parallel with the tubing running off to Oil Pressure gauge in my 1800, because there is no Oil Light in early 1800 vehicles...but loss of Oil Pressure, I want to know about, immediately!
When it comes to electrical gauges, I prefer to see Amps, and I've presented my case, Paul prefers to see Volts, and apparently that's also enough for you...but that's why they make Chocolate AND Vanilla!
Cheers
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One ice cream choice is called Neapolitan. I doubt very much it sells because the buyer anticipates serving people with preferences for chocolate or vanilla to the exclusion of the others.
To get all the information, you need amps, volts, and an alarm. Though I enjoy reading the debate over chocolate and vanilla, an open mind would see the benefits to all approaches, and maybe even envision a 21st century gadget which could safely (using an external shunt resistor) combine all into one monitor device. I imagine you'd like it if it could be made to look like a 60's gauge and fit the car.
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Art Benstein near Baltimore
"Trying to understand stupid people is like trying to pick up a turd by the clean end." --Lummert
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There is such a thing.
http://gaugepilot.uk/
Cameron
swedishrelics.com
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Cameron...you beat me to it...this is from the aircraft world, where information comes before cost (note also remote shunt option to address Paul's concern):
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You do know that's an AIRCRAFT gauge?
I agree with John & Phil.
Idiot Light: Essential, primarily because it can tell you that your alternator/waterpump belt has failed and you need to stop the car to prevent your donk from siezing up.
Ammeter: When you are driving around in the daytime, your battery fully charged and all you are running is the ignition, the gauge will be sitting on 0 practically and you won't notice the belt fail, 'cause it will still be on 0, practically.
Voltmeter: You turn the key on and it says 12v, now crank over the engine, if it drops more than 1.5v, you battery has a sad or stuffed cell. If your engine is running and shows anything besides 13.8v at charging rpms, your regulator or brushes need replacing. An ammeter can't tell you ANYTHING about the condition of the battery or charging system of use, because it can't measure voltage.
What ammeter, alternator and what gauge is your wiring Ron?
--
69 142S Overdrive + 69 164S Manual
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Paul;
An AIRCRAFT driver also needs info about his electrical system...and if you're making the point about Ampmeters being somehow inherently "unsafe", then they sure wouldn't build em into private planes...!
"An ammeter can't tell you ANYTHING about the condition of the battery"...a bit overstated, I think!
I've installed Ampmeters both ways...heavy wiring, internal Shunt, or small-gauge wire, remote shunt...and because one side was already connected to Battery I just added a resistor and switch, and I had both!
Cheers
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That's the spirit! (Now if only a quart of Neapolitan wasn't too much more expensive than a quart of vanilla...) :)
--
Art Benstein near Baltimore
What engineers say and what they mean by it:
"Close project coordination"
We should have asked someone else; or, let's spread the responsibility for this.
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What is the minimum gage wire that one should consider using for routing to an interior ammeter?
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Depends on the size of your alternator. For a 55amp alternator, you need 6mm squared. A rough rule of thumb is 1mm squared copper caries 10mm safely.
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69 142S Overdrive + 69 164S Manual
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You are to be commended for wanting to go the ammeter route. It shows whether the battery is charging or discharging, and exactly how much. Most cars had ammeters back in the day, but modern cars have volt meters because it's simpler and cheaper. What I've always done is disconnect the wire from the alternator to the battery and run a heavy gauge wire from the alternator to the ammeter and back to the battery. A more elegant way would be to use a shunt ammeter (which is actually a millivoltmeter)so you don't have to run the heavy wires, but that's more expensive.
--
1992 745, >500k km
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I agree an ammeter is the best way to go re monitoring charging/discharging but for the sake of argument and simplicity a voltmeter that you pay attention to should be enough to indicate if there is a problem. An ammeter also has to be watched as overcharge situations can destroy batteries and electronics before you will have any problems to notice. The best is having both, and while we are at it oil temp is really more interesting than engine coolant temp for accurate monitoring.
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Patrick, '68 220 , '53 GMC 4104, '97 VW Transporter.
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Patrick;
More information is always better (for those who care and know what to do with it), so you're preaching to the choir around here...anyone likely to be on this forum is also likely to know more about the technical details their car, and know how to interpret the info from gauges...
Both Amp and Volt meter readings require some interpretation, Volt meter a bit more IMO...I know what I'm looking at with either, and prefer an Amp meter ...the thing that made the decision for me is the fact that I want to know more about state of my Battery charge, and 0%-100% happens within a mere 0.8V...on top of that, system voltage gets pulled all over the place by Ch Sys and Loads...so info from a Vmeter is limited...
Cheers
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how about the red amp light on the 120? That is a vague bit of kit. With time the various levels of red used to mean something to me. Then I installed an alternator and have never had to see that red ruby of remorse since,
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Patrick, '68 220 , '53 GMC 4104, '97 VW Transporter.
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Patrick;
If you installed a "one wire" Alternator, it's no surprise you don't EVER see the AMP Indicator, because with that installation, you give up its' function! ...but if you have a "three wire" Alt installation (recommended!), you should expect to see AMP Ind glow full ON every time you turn On Ignition, and before Starting...just like before Alt!
...but I have to disagree...OE AMP Ind is not vague at all (sorry!)...when full ON (with engine running) it means either no Charging Sys output OR open Fuse1. Lightly glowing is a built-in side-effect, and a well understood condition at this point.
Cheers
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It's all good Ron. My amp light is wired correctly, just don't see it if the engines running.....it does glow a tiny bit if I have wipers, fan, h lights and at idle. Back in the day with my worrisome generator,that condition was bright red.
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Yes! Some conditions, such as slipping generator belts or shorted-cell batteries could throw off the interpretation made by voltmeter readings alone. A temperature-inspired alternator diode opening up or stator winding shorting could be missed relying on a voltmeter alone, just as the state of charge is difficult to guess by ammeter alone.
Both would be best, if you have the room, and can accommodate them safely.
Regarding how to wire it, I don't know if the 1800 suffers from the same challenge the 240 does: In the 240, the alternator and starter are part of the same mechanical assembly, vibration-wise. So the wire from alternator to battery connects at the starter. That leaves only the starter cable to the battery needing flexibility, high strand count, and safe mounting.
To add an ammeter requires a second large-capacity wiring between engine and chassis, along with its requisite care and attention to safety over time, temperature, and repeated flexing. And then, the shunt ammeter is the only practical safe way to get this information into the cabin.
--
Art Benstein near Baltimore
Every calendar's days are numbered.
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Whale;
An Ampmeter, correctly connected per the "H" diagram does not measure Starting or Load currents, only Charge and Discharge currents. See: http://www.sw-em.com/elecramb.htm
Cheers
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