changing ammeter to voltmeter

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Re: changing ammeter to voltmeter

Postby Kaegi » Fri Jan 12, 2018 4:28 pm

Jim100 wrote:Wont a voltmeter read 14 something if the system is charging and then 12 something if it is not charging?
jim

not necessarily. if driving down the road with lights and heat on high it probably wont read 14.2. the load will drag it down.

amp gauges forever. :lol:
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Re: changing ammeter to voltmeter

Postby hmaynord » Fri Jan 12, 2018 7:59 pm

"if driving down the road with lights and heat on high it probably wont read 14.2. the load will drag it down."
only if the alternator is undersized.

And how does an ammeter deal with an over voltage situation?
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Re: changing ammeter to voltmeter

Postby Kaegi » Sat Jan 13, 2018 1:36 am

hmaynord wrote:"if driving down the road with lights and heat on high it probably wont read 14.2. the load will drag it down."
only if the alternator is undersized.

And how does an ammeter deal with an over voltage situation?


never heard the term "over voltage situation". does that mean over charging? the amp gauge will read output of charging system. it will read discharge if not charging. the higher the reading the lower the voltage in battery and it will show more output as more demand is put on system. if battery is a bit low it will read a higher output then as you run engine it will gradually come back down to near zero out put as battery voltage comes back up. if the reg is not working and its over charging the amp gauge will show max output all the time. or the reg can be bad and not allow any charging so amp gauge will show discharge.
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Re: changing ammeter to voltmeter

Postby hmaynord » Sat Jan 13, 2018 6:45 am

OK. I agree the ammeter gives you better information. That just gets away from the point I’m trying to make.

As I’ve said, my goal is reliability. Here is my point: is that better information worth the costs? Those costs are (1) a longer charging circuit, which means some voltage loss when those amps reach the battery; and (2) more connections in that charging circuit, which means (a) more points of voltage loss, (b) when the alternator is outputting high amps, more points of heat generated, and (c) more points of possible failure.

So, for me, it’s an easy choice to go with the voltmeter, even though it will take me more time to realize the charging system has failed. That time is not critical, because I have the battery as a backup. It’s not the same as water temp and oil pressure, where I absolutely want to know those failures immediately.

I guess what I would like is a voltmeter that swings 90 degrees between 10 and 16, rather than 8-18. Then, a failure would be more obvious. I’d just have to get used to continual small movements of the needle being normal.
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Re: changing ammeter to voltmeter

Postby Jim100 » Sat Jan 13, 2018 7:35 am

My truck has a aftermarket wire harness. Painless maybe I cant recall what the guy said. The ammeter was done away with. physically removed.
Is it very difficult to wire in an aftermarket (maybe digital ) ammeter? I have a digital voltmeter in the dash which was easy but from what I gather a ammeter would be nice.
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Re: changing ammeter to voltmeter

Postby marklein » Sat Jan 13, 2018 10:10 am

Both monitor the charging system, if your alternator quits, the ammeter shows discharge, the voltmeter shows battery voltage. Imo, neither is better or worse, just the voltmeter has so many less inherent problems that ammeters are no longer used. If your charging system is in good condition, accessories should not pull voltage below where the regulator is set for more than a few seconds, if it can't keep up, it's either too small an alternator, or there's connection issues. If you have an overcharging situation, your ammeter goes over a certain amount, not specific, not telling you how much, a voltmeter may read 18 volts, way too high, I'd rather have the voltmeter myself.
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Re: changing ammeter to voltmeter

Postby PwrWgnDrvr » Sat Jan 13, 2018 11:05 am

hmaynord wrote:OK. I agree the ammeter gives you better information. That just gets away from the point I’m trying to make.

As I’ve said, my goal is reliability. Here is my point: is that better information worth the costs? Those costs are (1) a longer charging circuit, which means some voltage loss when those amps reach the battery; and (2) more connections in that charging circuit, which means (a) more points of voltage loss, (b) when the alternator is outputting high amps, more points of heat generated, and (c) more points of possible failure.

So, for me, it’s an easy choice to go with the voltmeter, even though it will take me more time to realize the charging system has failed. That time is not critical, because I have the battery as a backup. It’s not the same as water temp and oil pressure, where I absolutely want to know those failures immediately.

I guess what I would like is a voltmeter that swings 90 degrees between 10 and 16, rather than 8-18. Then, a failure would be more obvious. I’d just have to get used to continual small movements of the needle being normal.

The statement on costs is incorrect.
1. The longer charging circuit is irrelevant if the wire is sized correctly.
2. Proper connections add negligible resistance to a circuit which causes negligible voltage loss and heat generation.
Even in a charging circuit with more resistance before the battery (longer piece of wire) the battery will fully charge. It only reduces the time for a full charge. IE, look at the puny (high resistance) wire used on the leads of a bench top battery charger.

With an ammeter, the gauge sits in the center on the 0 line. With a running engine in the daytime, no lights, fan, etc, a failed charging system will be visible immediately. Not so with a voltmeter. In fact, it is difficult to monitor charging with a voltmeter before its too late. U'll find out the next time u park and it won't start. Even an idiot light is better than a voltmeter for monitoring the charging system.
Been driving swepts daily for 40 yrs this coming April. NEVER had a an ammeter problem in ANY truck EVER!

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Re: changing ammeter to voltmeter

Postby Kaegi » Sat Jan 13, 2018 11:55 am

all fears of amp gauges are irrational. fears fueled by baby boomers in the 70s who grew up on dummy lights and weed and dont know how to read one. ;/)
Even if I built a whole new custom system for a hotrod I would put an amp gauge in. you can even get the shunt type that do not run the charge wire through the dash. charge wire on those runs to a shunt block then 2 small wires run to the gauge. those are common in boats and equipment where the gauge is many feet away from the engine compartment.
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Re: changing ammeter to voltmeter

Postby Hobcobble » Sat Jan 13, 2018 12:30 pm

Kaegi wrote:all fears of amp gauges are irrational. fears fueled by baby boomers in the 70s who grew up on dummy lights and weed and dont know how to read one. ;/)


I guess they were too amped up.... :thinking :joker

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Re: changing ammeter to voltmeter

Postby Jim100 » Sat Jan 13, 2018 12:43 pm

So ammeter is more precise. One can probably get by with a voltmeter but be aware that you can be misled under higher load?
Ammeters have lost favor because they require exacting correct installation ?
Do it right and you have a better gauge in the ammeter is the take home?
Or is this one of those things that has its camps and there is agreement to disagree.

I want the best gauge to let me know that yet another voltage regulator has failed and that I have what's left in my battery to get home or near a parts store!
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Re: changing ammeter to voltmeter

Postby marklein » Sat Jan 13, 2018 12:44 pm

If you have a failing charging system, it doesn't matter which gauge you have, it will still fail. You can buy an adjustable regulator, more expensive, but the way to go.
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Re: changing ammeter to voltmeter

Postby 712edf » Sat Jan 13, 2018 2:51 pm

Option #3 is to get rid of your distributor ignition system & run a magneto. Crazy, but I've done it, makes the charging system less critical. :lol:

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Re: changing ammeter to voltmeter

Postby PwrWgnDrvr » Sat Jan 13, 2018 3:27 pm

Jim100 wrote:So ammeter is more precise. One can probably get by with a voltmeter but be aware that you can be misled under higher load?
Ammeters have lost favor because they require exacting correct installation ?
Do it right and you have a better gauge in the ammeter is the take home?
Or is this one of those things that has its camps and there is agreement to disagree.

I want the best gauge to let me know that yet another voltage regulator has failed and that I have what's left in my battery to get home or near a parts store!
jim

The only gauge that can tell u instantly the VR or ALT has failed is the ammeter. A fully charged battery will still read 14 volts for a period of time after the failure of the charging system.

Yes, do it right and u have more precise info with the ammeter.
The only problem is when people overload the system with more demand than it is designed for(foglights, steroes, etc). That's the same reason you get regional blackouts on hot summer days or houses burn down when ignorant fools install larger amp circuit breakers than the circuit wiring is rated for.
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Re: changing ammeter to voltmeter

Postby Jim100 » Sat Jan 13, 2018 4:14 pm

If anyone has a link to the easiest/ best step for step, or would be willing to describe the process for adding a aftermarket ammeter that would be great!?
Ill try google as well. and get a better voltage regulator.
And apologize for hijacking this thread!
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Re: changing ammeter to voltmeter

Postby marklein » Sat Jan 13, 2018 4:54 pm

Max on a 12v battery is 12.8, anything you read over that is surface voltage.
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Re: changing ammeter to voltmeter

Postby hmaynord » Sun Jan 14, 2018 8:24 am

man day! I think I'll just go back to a dummy light! :withstupid :lol: :lol:
Thanks for the discussion. I've learned a few things.
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