Wiring question--amp guage

[Russell Ashley]

I'm re-wiring my truck using an EZ-Wire harness and I'm wondering about the capacity of the original amp guage. I've rebuilt my cluster and I'd like to use it with no other aftermarket guages. The amp guage only says "D" and "C" so I don't know the maximum current it was calibrated for. I'm using a new 10-SI alternator which is not a one-wire alt. I told the parts guy it would go on an 1980 Camaro with A/C when I bought it.
My question is, How many amps is the stock guage designed to handle? Is my amp guage going to go up in smoke if I let my battery get low and the alternator is charging heavily for a few minutes? Is anyone using the stock guage with an alternator with no problems?

Any comments and/or advice is appreciated.

[justplainray]

i'm using the stock instrument cluster in my 56 and i too was concerned about the OEM amp gauge current capacity.
the alternator is from a 92 Camaro, with air and the output cable is bigger than a 10 gauge wire (i think it is 6 gauge wire)
i decided that the OEM gauge would NOT be up to the task at hand, so I wired the alternator output, via a 80 amp fuse, directly to the battery positive post, by-passing the amp gauge completely.
Of course now the amp gauge never shows a positive charge, it only shows discharge, but i do have an idoit light on the dash to warn of alternator trouble.
I've gone 10k miles is the the last three summers with no troubles.

justplainray

[Coupeguy2001]

The original generator was 25 amps. If you put even 40 amps through that ammeter, it will smoke the little shunt that the actual current goes through. I recommeng running two wires from your alternator.
One wire goes directly to the starter where the battery cable is attached, using 6 or 8 gauge wire, and a second 12 gauge wire that goes to the ammeter that goes through the original fuse box.
When your battery needs to be charged right after starting, the high current that the battery needs will go directly to the battery, through the big wire, not through the ammeter. When you turn on lights, etc, it will go through the ammeter.
There is a problem with that methodology, in that all charge current will go through the big wire, not through the ammeter.
The original ammeter functions as a pathway for charging and discharging. Which means that all charging current offsets all discharge current. So that the ammeter will show electrical system balance, which you always want to see as a positive current.
If you use the two wire system, you will only see a discharge on the ammeter. That means that the more current you draw from your electrical system, the farther negative the ammeter will display.
The answer is to swap the wires on the ammeter so that the more you draw, the more positive it appears.
Today's cars all have a volt meter, not an ammeter.
In today's cars, a volt meter is cheap, easy to wire in and indicative of a battery's state of charge. An ammeter that will display 130 amps is expensive and difficult to protect, and needs large wires to eliminate voltage drop.
So, if you use the two wire system, you will have to also install a volt meter as well. Otherwise, you will not actually know if your battery is charging.
Today's ammeter system is usually wired in with the ammeter wires not near anything because of the electromagnetic fields around the wire bothers other gauges and causes unwanted electrical "noise" that affects computerized engine management.
If you need other electrical functions, you need to add a fuse box that uses a fusible link of sufficient size, and fuse every wire that comes out of the second fuse box.
THe voltmeter will let you know if you have over extended the carge capability of your new alternator.

[Russell Ashley]

Thanks guys, you've pretty much confirmed what I suspected. I guess using the ampmeter is out so I'll wire the alternator directly to the battery. I already have an under-dash voltmeter that I will re-install for now. I was hopeing to avoid any after-market gauges as I don't want to cut the dash and don't like the under dash style.

[Coupeguy2001]

Russell, I don't smoke, so I used a chassis punch to punch a 2" hole where the cigarette lighter used to be. I installed a voltmeter there. It is up, out of the way, looks normal, and is easy to wire up there and doesn't hang down.
The only problem is if you use the original radio, it interferes with the factory radio. If you use a custom autosound radio, it will fit fine.
Your choice, and I seem to remember you had some dash / radio issues as well. I hope you get them resolved.

[butchp]

You gays are talking about a fuse panel, I have looked and did not find a fuse panel were there some trucks made without a stock fuse panel. If not where is your factory fuse panel located.

[mr48chev]

A 130 Amp alternator is only going to charge 130 amps if there is a 130 amp draw on the system. The rest of the time it will charge what is needed to recharge the battery and keep up with the demands of the components of the electrical system.

With just regular headlights, an am-fm cd player and heater the demands on the electrical system wouldn't be all that high for a 30 amp ammeter to handle but with halogen lights, AC, and maybe an amp for the sound system the demand quickly gets above what a stock ammeter will handle.

Ideally some vendor would have a good volt meter that you could replace the ammeter with in the instrument cluster and a matching gauge face that was changed from amps to volts. Then you would be able to tell the condition of the battery and what the alternator was charging volt wise.

I'm with Coupeguy2001 in that I would bypass the amp gauge and install a discrete volt meter in the truck. This Autometer Volt meter is 2-1/16" but would blend in with the stock instrument cluster somewhat if it were in a discrete spot on the dash. http://www.autometer.com/cat_gaugede...id=3895&sid=74

[Russell Ashley]

This is a really old thread. I must have asked this question before actually looking at the amp gauge. The solution was pretty obvious after I looked at the gauge.

[mr48chev]

Originally Posted by Russell Ashley

This is a really old thread. I must have asked this question before actually looking at the amp gauge. The solution was pretty obvious after I looked at the gauge.

OOPs we been busted for dragging out dead threads Buchp.

[OrrieG]

I hope my stock amp meter does not smoke. I am running a 64 amp alternator and EZ wire harness. According to another thread I found with EZ wire you can run up to 80 amps tru the stock gauge without a bypass wire. Guess we will see.... Nothing wrong with digging up the dead if it keeps someone from killing a living truck!

[Rude Dude]

You can always put a 300K Ohms or .3 Ohms Ceramic Resistor on the feed side of the amp gauge. This will cut down the amps to 40 amps to gauge.

To Calculate what size resistor you type in the values at this website.

http://www.ohmslawcalculator.com/ohm...calculator.php

Originally Posted by OrrieG

I hope my stock amp meter does not smoke. I am running a 64 amp alternator and EZ wire harness. According to another thread I found with EZ wire you can run up to 80 amps tru the stock gauge without a bypass wire. Guess we will see.... Nothing wrong with digging up the dead if it keeps someone from killing a living truck!

[Russell Ashley]

I don't think I would put a resister in series with the gauge as the full output of the alternator passes through the gauge to charge the battery. The gauge has extra tabs on it and I put a jumper across the gauge to divide the current that actually passes through it. I've been running my truck like that for over a year now and it has worked fine. The gauge doesn't peg when I crank it after it has sat for several weeks. I never tried it without the jumper so I don't know how the gauge would read if it wasn't there.

[_Ogre]

russell: i modified my stock amp meter to a volt meter using a 2'' volt meter
more info and details in my build thread in my signature line

[Russell Ashley]

Originally Posted by _Ogre

russell: i modified my stock amp meter to a volt meter using a 2'' volt meter
more info and details in my build thread in my signature line

Ogre, Love your truck. You have done some nice work on it. Converting to a volt meter was a neat trick, but being the old guy that I am I preferred to stick with the amp gauge, LOL. Just a matter of preference I guess.

[_Ogre]

thanks for the compliment russell.
i'm an old guy too, at least my body is
just not old skool when it comes to certain things
like ps, pw, ac, cruise and my volt meter

[OrrieG]

off topic, maybe another thread, but Orge what did you use for cruise? My column has the wiring and control button built in. Engine is 350, qjet carb, th350 trans. Did you use an aftermarket kit or adapt factory??

[_Ogre]

Originally Posted by OrrieG

off topic, maybe another thread, but Orge what did you use for cruise? My column has the wiring and control button built in. Engine is 350, qjet carb, th350 trans. Did you use an aftermarket kit or adapt factory??

i used a rosta universal cruise control. when i ordered the rosta unit they asked what steering column i had and sent me a replacement handle for the turn switch lever.

[OrrieG]

Thanks, I will look it up.

[sweet70beast]

I converted my 50 over to 12 volt about 12 years ago. I used a mid 80's alternator and the factory 50 wiring and gauge. I have never had a problem, I didn't wire in a resister like everyone says to do. If the truck takes a while to start and the battery is low the needle moves quite a ways over to the charging side and then slowly moves back to the center after the battery is charged back up.
This was a good thread to bring back up because I am putting a 75 350 in my 53 Sub and am going to use the wiring out of the 75 GMC pickup that the motor came out of. The engine harness, front and rear light harness and if I can make it work the inside cab harness.