Gnuman Posted November 13, 2004 Share Posted November 13, 2004 I'm looking at putting in a three mini-guage set where the ashtray used to be (previous owner discarded it, and I have no use for one), particularly as I hate the idiot guages on the dash. I'm looking at oil pressure, and possably vaccume, but which electrical guage should I go with? Would an ammeter be more useful to me or a voltage level guage? What gives more relevant info on the elec/charging systems? Also, is there a more telling place to put the vac guage than "where the manual tells you to"? THanks in advance for all your advice. . . Quote Link to comment Share on other sites More sharing options...
rcoaster Posted November 13, 2004 Share Posted November 13, 2004 I'm looking at putting in a three mini-guage set where the ashtray used to be (previous owner discarded it, and I have no use for one), particularly as I hate the idiot guages on the dash. I'm looking at oil pressure, and possably vaccume, but which electrical guage should I go with? An ammeter would be best, since it actually tells you if your charging system is working or not, and can warn you of problems that would pop up later. However, I've heard that it's not easy to wire up. But that was back in the 80's, so things might have improved then. Quote Link to comment Share on other sites More sharing options...
Cougar Posted November 13, 2004 Share Posted November 13, 2004 Since an ammeter has to be installed in series with the supply wiring to measure the total current in the circuit it is harder to install. You can use a shunt to handle the high current but this is still hrader to do and more expensive. I would install a voltmeter with the connection to it tied to the accessories fuse. A voltmeter will show you as much or more on the state of the charging circuit. You will be able to see how the voltage changes between idle and normal running speeds and what the voltage of the battery is while the engine is off if you want. Whenever the voltage starts going below 12 volts then you need to look for trouble. Normal running voltages will be between 12.5 and 14.8 volts most of the time. Quote Link to comment Share on other sites More sharing options...
kh0432 Posted November 14, 2004 Share Posted November 14, 2004 Forget the ammeter. The reason no car manufacturers use them anymore is because you can have a phase out of your alternator and it will still put out some amperage, but not enough to power your electrical load and charge your battery. People think that since there is movement on the ammeter, the charging system is working. Charging voltage is a much more accurate method. A voltmeter only requires a positve and negative connection and since it does'nt draw any amperage it can be wired to a constant hot wire or to an ignition wire. ( ignition prefered ). An ammeter on the other hand must be wired in line to the alternator output and thus requires a 10 gauge wire at minimum. There is also the potential for alot of damage if you were to get a short in that large of a wire if it is not protected with a fusable link. Quote Link to comment Share on other sites More sharing options...
Gnuman Posted November 14, 2004 Author Share Posted November 14, 2004 OK, sounds like I'm going with voltage on the guage. So do you think [oil pres, voltage, vac] is a good setup to point out any potential problems? and if so, where is the best place to attach the vac line? Quote Link to comment Share on other sites More sharing options...
Cougar Posted November 15, 2004 Share Posted November 15, 2004 If you don't have a coolant temperature gauge already I think I would prefer that over a vacuum gauge. Knowing the coolant temperature is much more important than vacuum to prevent damage. If you already have that then tieing the vacuum line to a port near the throttle should work well. Quote Link to comment Share on other sites More sharing options...
coloradosubarules Posted November 15, 2004 Share Posted November 15, 2004 volts, oil pressure and coolant temp. Going analog or digital? Quote Link to comment Share on other sites More sharing options...
NorthWet Posted November 15, 2004 Share Posted November 15, 2004 The choice between volt and amp meter depends on what you want. Think of the voltmeter as an odometer and the ampmeter as the speedometer. Which do you want? Do you want to know how far you've gone or how fast you are going? The voltmeter tells you where your electrical system was. It says if your battery has a charge and how much it still has. This is assuming that your electrical wiring is OK with good connections on power and grounds, and the battery isn't near death. If the battery IS near death, it can tell you that by watching the voltage sag when a load is put on it. It does *not* tell you immediately if the charging system is working; you can only tell this by monitoring it over a period of time and noting any trend. The ampmeter tells how much electricity is flowing and in which direction. It can tell you if your charging system is working, whether it is meeting current (pun unintended) demands. It can't tell whether the battery is discharged, accepting a charge, or getting overcharged. To get a good view of what your electrical system is doing you need both. How often do you see a car without both a speedometer and odometer? So, decide what is important to you. Quote Link to comment Share on other sites More sharing options...
cookie Posted November 15, 2004 Share Posted November 15, 2004 but for the last twenty years I have used voltmeters. If you are used to a voltmeter you can easily read battery and alternator condition and they take a half hour to install vs an hour and a half with an ammeter. Ammeters that have been improperly installed have been known to kill a car but I have never heard of a problem with a voltmeter. There is a reason my BMW came with a voltmeter not an ammeter.The last thing I saw come with an ammeter was my dad's 57 Chris Craft. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted November 15, 2004 Share Posted November 15, 2004 Voltmeters aren't bad, and am(p)meters aren't good... they just are. Yes, there is a reason that BMW uses them, and it is preference and prejudice and economics, not necessarily because one is better than the other. It is the same combo of reasons/compromises that has 'merican cars using a charge idiot light for decades. (My '77 Dodge has an ammeter, not that that is any kind of endorsement! ) It was erroneously stated earlier that ammeters draw power to operate and voltmeters don't. This is opposite, as the voltmeter actively uses electricity to deflect its needle, whereas the ammeter passively uses the magnetic field caused by current flow. The voltmeter does not show the current state of the charging system; it shows an integration of the previous states of the charging system. I drove 250 miles on a dead alternator and my voltmeter did not vary significantly until darkness fell and I had to turn on my lights. My ammeter showed a discharge all along. Again, not trying to say that one is better than the other, but that they are complimentary. If you have room for just one, pick the one that "fits" for you. Quote Link to comment Share on other sites More sharing options...
Gnuman Posted November 22, 2004 Author Share Posted November 22, 2004 Ummm, if not "coolant temp" what is that temp guage that is on the instrument cluster? I know it says "engine temp" but, it checks that by measuring the coolant temp (on every car I have ever seen, that is), and I have not seen any cars without them (that I can recall, anyway). Are there Subies out there without that guage? Quote Link to comment Share on other sites More sharing options...
frag Posted November 22, 2004 Share Posted November 22, 2004 Ummm, if not "coolant temp" what is that temp guage that is on the instrument cluster? I know it says "engine temp" but, it checks that by measuring the coolant temp (on every car I have ever seen, that is), and I have not seen any cars without them (that I can recall, anyway). Are there Subies out there without that guage? The instrument cluster temp gauge is let's say one notch better than an idiot light. I dont remember the exact temps but when I tested mine, i saw that it stayed still (at «normal» from around 160*° F to 195° or something until the rad fan kicked in and lowered the temp again at which time the stat closed and round and round it went. A real temp gauge shows all those fluctuations not the gauge that's already there. I guess they dont want us distracted. It's probably enough that the gauge starts going up around 200° F. What do you think? Quote Link to comment Share on other sites More sharing options...
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