Alternator/ammeter

[GPster]

This question has probably be covered more than what springs to use in a Mustang II front end conversion but if I spend time looking in the archives for an answer I'll forget what the question was. So here goes. My truck project will probably be wired so that the '48 to '53 Chevy/GMC dash gauges are in use (thanks Enjenjo and Sumner). There is an ammeter in the gauge set, It of course is 6V and the new wiring will be for a 12V system. Now I had a single wire GM alternator built for this and the one wire goes from it to the battery,right? This alternator is probably the 57 amp variety but if the wire goes directly to the battery there's no way to tell if it's charging. Should the ammeter be in that wire between the alternator and the battery with the battery side of the ammeter also feeding the key switch  or is the ammeter only supposed to tell you that you have something turned on after the key? Maybe the in-dash ammeter is not heavy enough to deal with the output of an alternator? Talk to me. I'm not figuring anything out talking to myself. GPster

[enjenjo]

I'll have to check my files, but if you wire it into the circuit between the alternator and the battery, it probably won't hold up. as I recall those ammeters are only 30 amp, and most alternators exceed that by a good margin. In my files is the way to wire it up, according to Skip, I've used it, and it works.

[wvcab]

just did this....

wire from altenator goes to battery +
wire from ammeter goes to battery +
wire from other side of ammeter goes to key.

if turning on accys (lights) with motor off and guage shows a charge, reverse the 2 wires on ammeter.

robert

[enjenjo]

That's it, just wanted to check before I said it.

[parklane]

I did up a 54 p/u several years ago, and the gauges are very similar to the 48-53. Get newer gauges out of Chev school bus, at least to 70's as they are  almost a bolt in, and have the newer as in 12V gauges. There is a light for brakes on the ip, and i hooked it up as an idiot light for my alt.

John

[GPster]

That points me in the right direction. Thanks. I thought that might be the way to go. I wanted a clean (simple) set-up and rather than have two wires on the positive lead on the positive side post of the battery I started looking for an insulated terminal boss that I could put three wires on (anternator, battery and wire to go under the dash for ammeter) and fasten it next to the battery box on the firewall. I got greated with the "make, model and year" and when I said I didn't have that information I was told "we don't have that". I've got a 100 amp ammeter that I just might mount under the hood so I can see if the alternator is workin while I'm watching it work. I'll use the one in the dash to tell me if the lights are on. GPster

[wvcab]

most people run a heavy cable from the battery to the starter seleniod, then run a wire to the ammeter and the attenator... using the "battery side" of the selenoid as a "junction post"

robert

[GPster]

most people run a heavy cable from the battery to the starter seleniod, then run a wire to the ammeter and the attenator... using the "battery side" of the selenoid as a "junction post"robert

Had it that way for awhile but now the battery and alternator are on the dash/driver's side. The big battery wire I can get it around the back of the engine and to the starter and insulated fairly easy and the only little wires other than that on the passenger side are the wires to the coil resister and  the solenoid. So the passenger side has only the distributor, coil, resister, solenoid and starter. And the full voltage wire from the solenoid to the coil for starting. The battery on the passengers side of the firewall interfered with the heater ( which I may never have but the blower will serve as a defroster). I've already burned the insulation off one one wire off the alternator. Trying to get that wire cleanly from the lower/front driver's side of the engine so that it doesn't get in the fan or exhaust manifold to the rear of the other side of the engine just isn't in my realm of thought at this time. Don't take offence. I'm just writting this stuff down so if I ask myself tomorrow why I did it this way I'll have my excusses written down. GPster

[wvcab]

gpster

no offense taken, i just (last weekend) removed the wiring harness for the engine compartment, and rewired it from scratch, moving the selenoid under the cab, the ignition control module, in the right kick panel, and the coil to the left lower fender well as well as adding a new one wire altenator, and getting rid of the external voltage regulator. was attempting to "neaten up the under hood apperance.

i like the looks of the clean up job, so far.   now to get the hood done....

[GPster]

gpster

no offense taken, i just (last weekend) removed the WIRING HARNESS for the ENGINE COMPARTMENT, and rewired it from scratch, moving the SOLENOID under the cab, the IGNITION CONTROL MODULE, in the RIGHT KICK PANEL, and the coil to the left lower FENDER WELL as well as adding a new one wire altenator, and getting rid of the EXTERNAL VOLTAGE REGULATOR. was attempting to "neaten up the under hood apperance.
i like the looks of the clean up job, so far.   now to get the hood done....

The caps don't apply in my case. There are no hood sides and I left that big hunk of a six under the hood so people can't see through from one side to the other. GPster

[Skip]

10 Gauge wire from the Alternator to the right post of the ammeter.
This post will also have the feeds to your ignition switch, headlight switch, any relays and your fuse box.

On the left post of the ammeter, connect a 10 gauge wire and run it down to the battery (batery cable post on teh starter solenoid)

Turn on the lights (without the engine running).  The ammeter shold go to discharge.  If it moves towards charge, reverse the position of the wires on the back of the ammeter.

[ram-rod]

amp meters are one of the largest causes of old auto fires

they are by design a point of resistance in the circut  

please think about having it converted to a voltmeter  these little beautys tell you far more than any amp meter

I think ron francis used to post a warning in his adds about amp meters
 

if i type more it will turn into a long tome
amp meter runs in series   (bad)
volt meter parallel.  volt meter tells battery volts when key on . then goes up slow to 13.8  when you start and rev.  then if it drops back to under 13
with high beam and aircon you may need the alt  recoed

[Skip]

amp meters are one of the largest causes of old auto fires

they are by design a point of resistance in the circut  

please think about having it converted to a voltmeter  these little beautys tell you far more than any amp meter

I think ron francis used to post a warning in his adds about amp meters
 

if i type more it will turn into a long tome
amp meter runs in series   (bad)
volt meter parallel.  volt meter tells battery volts when key on . then goes up slow to 13.8  when you start and rev.  then if it drops back to under 13
with high beam and aircon you may need the alt  recoed

Ron Francis is the biggest reason ammeters have gotten a bad name.  Ammeters are NOT the cause of automotive fires.  If anything, they're a PROTECTIVE DEVICE.  If they're overloaded, they'll open just like a fuse.

Volt meters are little more than an idiot light with a needle.  They tell you nothing about the state of the BATTERY or the charging system.

Depending on the type of battery - lead acid, low maintenance, maintenance free, or gel-  the indicated voltage can be anywhere between 12.75 and 16 volts.  If you have 16 volts on a system with a lead acid battery, you have a problem, your alternator's overcharging.  

If you have 13.8 on a system with a gel battery, you're not charging it at all.

You see, you need to know what kind of battery is in the vehicle then you have to make mental calculations to verify the state of the charging system.

With an ammeter, on the other hand, regardless of the type of battery, you'll see one or two amps when the alternator has replaced the initial drain caused by the use of the starter motor.

As for the safety factor of a volt meter over an ammeter regarding the "heavy wire" issue Ron Francis is so prone to use, it's simply hogwash.

You can't run your vehicle w/o having power to the ignition switch, the fuse box, the headlight switch, various relays, etc.  How do you suppose that power gets in there?  It's that same big fat wire Ron Francis complains about.

The only reason most new street rods and customs should shy away from ammeters is because f the widespread use of electric fans to overcome improperly tuned small block Chevy engines.  The electric fans necessitate the use of an enormous alternator in order to maintain adequate charging current at idle and, should the regular go "full field" you'll pop a 60 amp ammeter and be dead in the water.

An ammeter, you see, should only indicate the current above and beyond that needed to operate the vehicle that is flowing into the battery.  If the alternator full fields, it'll peg an ammeter AND a volt meter.  The ammeter will pop while the volt meter won't.  The open ammeter will prevent you from exploding your battery as the action of the ammeter going "open circuit" removes the charging voltage from the battery.

A volt meter, on tehn other hand, doesn't have this protective attribute.  Your alternator will continue to dump excessive current into the battery until it heats up, gasses and – in the event of a spark occurring – explodes.

What would I rather have in my car? An Ammeter any day.

[GPster]

Thanks, everybody is right and working from the information you've given with the supplies I have this is what I think I'll try. The negative battery cable will go to the case of the alternator and a jumper will continue on to the engine block. The 10 ga. secondary wire off the negative side post battery terminal will go to a body ground. The large cable from the positive side post battery terminal will go to the 12 volt solenoid on top of the 6 volt starter. The 10 ga. secondary wire off the positive side post battery will go to the "-" side of a 100 amp ammeter which will be mounted under the hood near the battery. The ammeter will be there as a positive junction place and as an under hood indication of charging. I already have it and it will serve as to keep the high amperage from having to find it's way in and out of the firewall to reach the stock dash ammeter which is not up to the full task. The "+" side of the under hood ammeter will have the positive  wire coming from the alternator and the wire going through the firewall to the ignition switch  and the stock ammeter which might only tell me if something is still "turned on"
or "shorted". The only load that the stock ammeter will see is the ignition, starter solenoid, lights and the motor and speed control resister for the heater/defroster fan. I sure can be complex trying to make things simple and all of this while celebrating my 38th wedding anniversary and the company of our 4 year old granddaughter. I can only do one thing at a time. GPster

[ram-rod]

modern cars have a fusable link  and a volt meter  this means you dont have to pull the dash apart in the event of a failure

go for it gpster at the end of the day its about what you want