ENOS Wiring problem

hotrodbob · February 02, 2005, 12:23:54 PM

Ok, I got tired of the light show under my dash and now there is a fresh ENOS wiring harness in the car. Everything works, but now the amp gauge will not show discharge only charge. I have tried with key on and key off, but even pulling out the head light switch will not cause a discharge to show on the gauge. Anyone got any Ideas on this? I'm using the stock gauges, ign switch.

The guy that installed it said he spoke to the ENOS guys and they said nothing is wrong. I kinda disagree.

Just tried to find a web address or phone number for ENOS but couldn't.

kb426 · February 02, 2005, 12:54:47 PM

I'm not much help do to memory failure but I had the same problem years ago. I didn't have the ammeter hooked into the right place. I can't remember what I did to fix it. Sorry.

HOTRODSRJ · February 02, 2005, 04:34:16 PM

True system amp gauges should show SYSTEM discharge and charging but some wiring systems only show a discharge when the engine is running and there is no charge present out of the alternator. This depends on how the battery bus and alternator bus is designed and routed.

The old systems used to show discharge by simply pulling the headlights on with the ignition switch on...but engine not running and in some cases even without the ignition on.

For the gauge to work correctly the entire load HAS TO COME THRU the amp gauge shut which usually means the charging line and/or battery bus is involved. Without seeing how the system is wired or a schematic I can't tell.

But, a true test is to start the car without an alternator belt on and then for sure regardless of the type or how it's wired...it should show discharge. You can do this even if the water pump depends on the alternator being belted up to run the water pump. No problem for a 30 second check.

hotrodbob · February 02, 2005, 04:50:47 PM

Great info. I had the stuff done for me so it's back to them with the info.

Got some other things to check as well.

Thanks

47convert · February 03, 2005, 09:39:29 AM

Quote: For the gauge to work correctly the entire load HAS TO COME THRU the amp gauge shut which usually means the charging line and/or battery bus is involved

Exactly why no-one should consider using an ammeter. I'd replace it with a voltmeter if I was you. Ammeters cause lots of problems.

C9 · February 04, 2005, 07:36:59 AM

I've never had a problem with an ammeter.
The use of voltmeters by the aftermarket wiring companies is a sales pitch.

The main load wire - usually 10 gage - has to come into the car's interior somewhere along the line so the so-called safety aspect of a voltmeter is a moot point.

Find the car's main source of supply.
It should be the 10 gage wire emanating from the hot side of the starter solenoid on GM or Ford products and ChryCo's are similar to Ford in most cases.
Splice the ammeter into this 10 gage wire where convenient and it will show charge and discharge.

If the interior run of 10 gage is not long enough to do what you want, remove it from the starter solenoid and pull it into the interior.
Hook that to one side of the alternator.
Run another 10 gage wire from ammeter to starter solenoid and connect the interior side of that to the other ammeter post.

Test the ammeter for proper connections by turning on the headlights with the engine off.
You should see about 10 amps on the discharge side.
If the ammeter needle deflects to the charge side with the headlights on (engine still off) reverse the ammeter's 10 gage wire connections.

You'll probably find that several circuits in the car tap directly off the load side of the ammeter and these circuits will be stacked on the ammeter post or tap off the wiring panel and only one 10 gage wire goes to the wiring panel from the load side of the ammeter.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Detroit quit using ammeters because voltmeters are a lighter duty - read cheaper - gauge than an ammeter as well as they can run a lighter gage wire to the voltmeter.
Saving a few cents per car with the lighter gage wire is not to be sneezed at when you're dealing with the quantities of cars coming off the line.
It can add up to some big bucks.

Back in the mid-60-'s I think it was, Ford used to have an employee suggestion box and they paid employees for ideas that were incorporated into the manufacture of the cars.
A suggestion that saved a nickel per car would net the employee a $2000. check.

HOTRODSRJ · February 04, 2005, 09:40:27 PM

C9....with all due respect,... me thinks you are a smiggin cynical here...I will argue all day long that ammeters are far more problematic than voltmeters and was IN FACT done for safety and moreover to eliminate voltage drops....not cost savings or simple sales pitches at all. Anytime you introduce current to any device, the overall failure/reliability rates go exponentially.

I personally have repaired more cars and trucks with electrical problems because of bringing large currents thru the dash to the block to the gauge and so forth including ammeter issues. These are usually junction issues creating large voltage drops or overloading of fuse blocks OR DEFUNCT AMMETER GAUGES.

In fact, the factories OEMs have established a "gold industry standard" (if you look at your modern rides) that they relay everything that requires over 10amps and keep the circuits as short as possible AND out of the interior. This is NOT a cost saving issue either and in fact is over double the cost....so it's about reliability, safety and eliminating voltage drops in wires and connections.

The safety factor is getting rid of a potential short in the interior with such a high load carrying wire if involved in an accident. Because it is not protected to a lower level such as A 10amp, 40amp or 60amp fused line etal, the heavy current lead could easily spark in an accident an ignite possible fuel situtions/scenerios in the interior. So, safety is NOT moot at all. (One of the more obscure facts from the old firey Pinto debacle in the mid 70s...if you remember being hit from the rear and exploding in a ball of flame,...it was found out that Pintos with ammeter gauges also ignited the interior that filled with pressurised fuel and did not happen in the case of interiors without when the car was jammed into a car in front of it.) This very subject (high current buss management) was highlighted at the University of Michigan's 2003 Automotive Conference on Automotive Engineering as well and every other slide/presentation was eliminating high current loads from the interior. Also a reason the high current relays and fuseblocks are now residing in the engine compartment instead of in the interior. My next car will in fact have the complete relay panel and fuseblock mounted outside the interior. I know in some rod applications its hard...but as an alternative the trunk can be used.

Also, another reason the OEMs went this way is that a voltmeter is a better tool for analysis of the overall system. The voltmeter can tell you if you are charging or discharging and moreover the health of the system voltage. It is also more accurate. This problem is exacerbated by age as well with junctions corroding etc. ...so that is why we are replacing alot of these systems today in older cars! Today's cars could easily go 100s of years of electrical service both with the design upgrades and materials.

"Splice the ammeter into this 10 gage wire where convenient and it will show charge and discharge" will not always work. Depends on how the charging system is hooked and and where. I respectfully submit that one gets a qualified person to determine this on an application if one cannot determine this themselve. And, I wouldn't splice the main circuit feeder bus for anything. Again, you are introducing voltage dropping junctions that could heat up under high loads. Not a good thing in my opinion.

Now...am I saying that ammeters are a bad thing when correctly installed and maintained......nope. I am just saying that voltmeters are a better mousetrap for lots of reasons.

Another side note and then I will get off my soap box. Now adays...10ga wire is NOT enough to feed most systems. This is especially true at the alternator leads to the battery or system. Many of us want high watt headlights, air, big stereos, electric seats, winders and huge cooling fans...well you get the idea. A simple unfettered 7 foot run of 10 gauge at 60amps produces a whopping half volt drop....then add connections and you can easily be talking almost volt! At 60amps that's 30 to 60 watts that are getting eaten up....all heating your wire. That's like a high beem headlight heat. I recommend at least an 8ga or adding an additional parallel 10 gauge to accommodate these current hogs. Just food for thought.

C9 · February 05, 2005, 07:59:01 AM

Good points - and no offense taken.

Splicing the ammeter into the main load wire was a poor choice of words.
What I meant here was to cut the wire, install terminals and install the ammeter in series.

More than likely voltmeters today are done for the safety aspect, but from what I've read the early VM's were done as a cost cutting measure.

I'd bet too that the ammeters and associated wires you've had problems with were brought into the interior without grommets and other devices to protect the wire.
I see some amazing things done with wiring in hot rods and I'm sure you've seen the same.

That's quite a voltage drop in only 7' of ten gage.
My experience has been what looks to be zero voltage drop with a 4' run of ten gage.
That's comparing voltage at the battery's main positive cable where it connects to the starter solenoid and at the end of the 4' run of ten gage where it connects to a relay utilizing the same ground point connection in both cases.
A good quality digital voltmeter was used and an analog voltmeter shows the same.
Not laboratory instruments, but accurate enough for field work.

Far as the choice of wire gage goes, ten gage seems to be sufficient for most of the hot rods I get involved with.
Simple cars with just the basics, ignition, lights, heater (sometimes) and radio (occasionally)
Which means ten to twenty amps running in the ten gage (lights and heater).
Ignition is not quoted here because it has it's own source at the solenoid and does not utilize the main run of ten gage.

I agree that the well equipped street rod with all the modern paraphernalia requires more than one ten gage wire or a larger wire as the main feed.

Interesting thoughts about setting up the wiring panel etc. under the hood or in the trunk instead of under the dash.
I'd guess that most hot rodders wouldn't want the panel under the hood on the simpler cars - thin fenders etc. - but it could be nicely done on the fat fendered cars.

In view of all the gas tanks in the trunk I'm not sure the wiring back there is the best set up either.

Last choice in panel location is under the seat which is convenient, but probably no safer than an under-dash setup.

Perhaps we need to think about getting our fuel tanks under the car within the perimeter of the frame and out of the trunk and off the exposed rear of the Deuces.
Problem here is lack of capacity, but twin tanks would cover that fairly well.
I'm planning for a pair of tanks within the frame perimeter in front of the rear axle.
Capacities would run from about 5 gallons each for a simple box and if there's a small extension run forward they would end up about 7 gallons each.

Interesting discussion and educational about the factory wiring et al and I'm sure safety - specially nowadays with our overly litigious society - is the big reason why Detroit does what it does.
Saving money enters into it as well.
Granted, relays cost more than wire, but maybe that's a wash considering all the wire we have in modern cars.
Not to mention the 32 volt systems that are coming on line with their commensurate very small wire gages.
I believe much of the circuitry will be 20-22 gage wire.
That'll save Detroit some money, but it seems that mechanical weakness of the wiring could create problems not seen with the structurally stronger wiring in use today.
Easily cured by grommets, good harnesses and proper support no doubt, but I have yet to see a modern car that didn't need a few tie wraps added to forestall potential problems.

Even so, I have yet to see a failed ammeter - or a failed voltmeter for that matter.
Making an ammeter my first choice for the new car - with thoughts about adding a voltmeter as well.

PeterR · February 05, 2005, 11:03:38 AM

Carefully installed the ammeter will not cause problems, but requires considerable effort to do it properly. The ideal solution is to use a remote shunt ammeter.

A quick description for those not familiar with this type of instrument. A typical automobile ammeter has a thick copper strip running between the terminals. This "shunt" carries the large currents passing in and out of the battery, and the meter movement is in fact a sensitive volt meter which measures the small voltage drop across the shunt.

A remote shunt ammeter has the shunt at the engine and a pair of light gauge wires carry the small current (about .05A) required to operate the meter movement. These are used routinely in marine applications where there is a long distance from the batteries to the cockpit instrument panel making a direct reading type impractical and have also been used on some cars and trucks.

"Off the shelf" remote shunt meters are unlikely to match your other instruments, however all is not lost if you do not mind a little fiddly work. Some conventional ammeters have the shunt mounted on the terminal studs outside of the case allowing it to be easily be removed and relocated in the engine bay. On most older automobile gauges bending up a couple of tabs on the ring that retains the glass allows the unit to be dismantled and the shunt removed. Later instruments with shunt inside the case and crimped glass rings are too difficult to modify.

Some readers will believe all this simply reinforces the reason for using a voltmeter which only requires one terminal spliced to the ignition circuit and the other to ground. To provide an accurate measure of battery voltage the voltmeter should take the reading at the battery, not at the end of a long cable subject to load dependent voltage drop.

Running a pair of light gauge wires from the meter to the battery lead terminal at the starter and the main ground cable will solve the voltage drop errors, but also flatten the battery if the vehicle is left standing for long periods. This is overcome by fitting a relay in the +ve lead close to the meter with the relay coil feed from the ignition. The meter will then monitor the real battery voltage but be disconnected when the engine is not running.

Skip · February 05, 2005, 05:30:48 PM

Quote from: "HOTRODSRJ"True system amp gauges should show SYSTEM discharge and charging but some wiring systems only show a discharge when the engine is running and there is no charge present out of the alternator. This depends on how the battery bus and alternator bus is designed and routed.

The old systems used to show discharge by simply pulling the headlights on with the ignition switch on...but engine not running and in some cases even without the ignition on.

For the gauge to work correctly the entire load HAS TO COME THRU the amp gauge shut which usually means the charging line and/or battery bus is involved. Without seeing how the system is wired or a schematic I can't tell.

But, a true test is to start the car without an alternator belt on and then for sure regardless of the type or how it's wired...it should show discharge. You can do this even if the water pump depends on the alternator being belted up to run the water pump. No problem for a 30 second check.

A correctly wired automotive ammeter will have ALL of the loads attached to the charging device side of the ammeter and ONLY tyhe battery (at the starter solenoid end of the cable) connected to the other side.

With the engine off, current flows between the battery and the loads THROUGH the ammeter.

With the engine running, the charging device supplies the necessary current and only a trickle charge fllows into the battery (after the initial top-off charge to replenisg voltage drop due to engaging the starter motor) so the ammeter needle should rest just slightly into the charging zone.

HOTRODSRJ · February 07, 2005, 09:34:14 PM

Hey Skip! Haven't seen ya around for awhile. I knew this was the perfect post for you!

I do have a quick question for you. What do most gas gauges resistances/impedances look like? Any idea? I don't know of a standard do you?

Skip · February 07, 2005, 09:41:56 PM

Quote from: "HOTRODSRJ"Hey Skip! Haven't seen ya around for awhile. I knew this was the perfect post for you!

I do have a quick question for you. What do most gas gauges resistances/impedances look like? Any idea? I don't know of a standard do you?

Empty Full
VDO 10 Ohms 180 (could be backwards)
Ford 73 10
SW/Sun 240 33
GM 90 0
GM 0 30
Autometer 30 250 (could be backwards)
Moon 31 199 (could be backwards)

I say these readings could be backwards because grounding the sender wire at the gauge makes they needle read full, which is opposite from the specs I was given. i.e. grounding the wire should force the needle to empty.

Skip · February 07, 2005, 09:45:51 PM

Quote from: "HOTRODSRJ"Hey Skip! Haven't seen ya around for awhile. I knew this was the perfect post for you!

I do have a quick question for you. What do most gas gauges resistances/impedances look like? Any idea? I don't know of a standard do you?

Oh, yea. Been prettyy busy wiring cars after work so I don't get on line much. Inbetween wiring jobs right now (that'll change tomorrow night) so I have a bit of free time.

I'm at work before 7:30 (after an hour's drive) then I wire cars Mon-Thur every week in the evenings. Friday light's the tiome to relax and that DOESN'T mean on the 'puter. Sat & Sun is catch up on my own stuff time.

Been too cold to work on the '34 so I've been catching up on all tyhe 'lectric train jobs that have been piling up (converting a guy's fleet of diesels to DCC)

choco · February 09, 2005, 04:51:02 AM

Hello everybody.
Choco speaking.
Car manufacturers switched to Voltmeters (even though, in the early 60s, they were labelled Amps but were really voltmeters) because of the change from generators to alternators. Generators were current sensing, alternators are voltage sensing. It's still OK (sorta) to put an ammeter in series with the alternator charge wire, but today's wiring systems are designed around using a voltmeter.

I really like it here. I should visit more often. I love you all.
BCNU

GPster · February 09, 2005, 07:18:00 AM

Quote from: "choco"

Car manufacturers switched to Voltmeters (even though, in the early 60s, they were labelled Amps but were really voltmeters) because of the change from generators to alternators. Generators were current sensing, alternators are voltage sensing. It's still OK (sorta) to put an ammeter in series with the alternator charge wire, but today's wiring systems are designed around using a voltmeter.

BCNU

Isn't it nice every once in a while to be told the real reasons along with the pitfalls, quick fixes and catastrophies? GPster