High reading in my amp meter

[OCTAVIOUS]

1970 Coronet R/T vert.
440 auto with Rallye Dash
Original charging system

Car was running good and the amp meter would run up to 20+ after start up and slowly head back to just above positive after a drive and do its normal thing

Few days ago the meter now goes up to 30 plus after a start up and now won’t return to below 15 amps i have tried to regulators both go to ~ 14v

Here is what I know…

1)The output from the alt terminal is what the amp gauge reads
2) volts from regulator above idle is 13.8-14v
3) battery reads 12.7v at rest and follows voltage reg in running condition.
4) drove for 45 minutes still doesn’t drop below 17amps where it use to go down to 3-4amps
5) connections from everything in the engine compartment has been pulled and cleaned including bulkhead connections.
6)at a stop light it will drop to negative on the amp meter

Suggestions

 

[kiwigtx]

1. You have a large current draw while driving,
2. Your battery needs a bigger and longer charge than normal - bigger than what you have seen recently
3. The battery could have a dying cell
4. The ammeter could have a bent needle causing it to stick in place.
5. The terminals at the back of the ammeter might be loose or burning.....worth checking to eliminate that potential problem.
6. The battery may need electrolyte top-up...depending upon type.

 

[OCTAVIOUS]

Tried two different batteries and used a stand alone charger on them before testing last time

Your Number 5 or a ground is my fear
Keep them coming

 

[72RoadrunnerGTX]

Tried two different batteries and used a stand alone charger on them before testing last time

Your Number 5 or a ground is my fear
Keep them coming

Assuming the ammeter returns to center when shut off or battery disconnected. Not seeing how a connection issue at the ammeter studs would create a high charge indication. Normally, a high abnormal charge rate would indicate a battery problem, were the batteries tried load tested, verified as good? You said all stock charging system, any added loads connected at the battery or starter relay?

 

[OCTAVIOUS]

Assuming the ammeter returns to center when shut off or battery disconnected. Not seeing how a connection issue at the ammeter studs would create a high charge indication. Normally, a high abnormal charge rate would indicate a battery problem, were the batteries tried load tested, verified as good? You said all stock charging system, any added loads connected at the battery or starter relay?

Yes gauge is reading what is being produced and it does go to center even negative at low idle which is normal but go above ~1800 rpm goes to 20 amps on guage

Nothing added even run points for ignition.

I put a clamp on DC amp meter on the positive wire to battery and saw 9amps the output from alt was 17amps
Got to be going somewhere. Gauges all operate normally

 

[twecomm]

I had posted this article over on Electrical Forum. Not inferring you battery might be at issue, but... Just some food for thought.
Seven Things That Go Wrong With Car Batteries

 

[72RoadrunnerGTX]

Yes gauge is reading what is being produced and it does go to center even negative at low idle which is normal but go above ~1800 rpm goes to 20 amps on guage

Nothing added even run points for ignition.

I put a clamp on DC amp meter on the positive wire to battery and saw 9amps the output from alt was 17amps
Got to be going somewhere. Gauges all operate normally

Convertible? Power windows? Not many things drawing power from the battery side of the ammeter but some convertible top pumps are connected at the battery side of the ammeter at the ammeter. Some platforms draw power for power windows on the battery side of the ammeter but are key switched via a relay.

 

[OCTAVIOUS]

I had posted this article over on Electrical Forum. Not inferring you battery might be at issue, but... Just some food for thought.
Seven Things That Go Wrong With Car Batteries

Top, yes And when I hit that switch guage drops for a second then recovers

Power windows, no power windows

 

[Nacho-RT74]

Those high load accs are on the batt side of the ammeter but they are punctual suckers, not constant. They obviously cause a small charge reading after being used, just like when you cranked up your engine.

Some idea comes to my mind, maybe could be some crazy, but… what about if while the amm is on ~15 amps reading you install a temporal jumper wire between alt post and batt?

Is just an idea, but I’m thinking on a bad contact along the charging circuit on batt side causing a resistance requesting that new load. That jumper could discard a batt issue if the amm keeps around same reading with the jumper wire?

As mentioned I’m just thinking out loud. I might be wrong

Next, could be disconect the power windows and top relays to check if there is some draw there!

 

[BDnFL]

1970 Coronet R/T vert.
440 auto with Rallye Dash
Original charging system

Car was running good and the amp meter would run up to 20+ after start up and slowly head back to just above positive after a drive and do its normal thing

Few days ago the meter now goes up to 30 plus after a start up and now won’t return to below 15 amps i have tried to regulators both go to ~ 14v

Here is what I know…

1)The output from the alt terminal is what the amp gauge reads
2) volts from regulator above idle is 13.8-14v
3) battery reads 12.7v at rest and follows voltage reg in running condition.
4) drove for 45 minutes still doesn’t drop below 17amps where it use to go down to 3-4amps
5) connections from everything in the engine compartment has been pulled and cleaned including bulkhead connections.
6)at a stop light it will drop to negative on the amp meter

Suggestions

Using 50 year old gauges to troubleshoot is not a good idea.
Get a handheld volt meter to check voltage readings, some meters even read DC amps.
If you don’t have a volt meter drive the car to an auto parts store and have them load check your alt. and battery.
That will eliminate two parts of the puzzle.

 

[OCTAVIOUS]

Using 50 year old gauges to troubleshoot is not a good idea.
Get a handheld volt meter to check voltage readings, some meters even read DC amps.
If you don’t have a volt meter drive the car to an auto parts store and have them load check your alt. and battery.
That will eliminate two parts of the puzzle.

I’m using a clamp on DC amp meter and a fluke 87 volt meter….just so happens. They line up with the 50 year-old gauge.

 

[72RoadrunnerGTX]

The OP indicates in post 5 he is using a clamp-on ammeter to break down where current is flowing. I would clamp that ammeter to the power lead to the top switch, or disconnect the top switch to eliminate that circuit as drawing the extra current not accounted for in the measuring so far.

 

[OCTAVIOUS]

Those high load accs are on the batt side of the ammeter but they are punctual suckers, not constant. They obviously cause a small charge reading after being used, just like when you cranked up your engine.

Some idea comes to my mind, maybe could be some crazy, but… what about if while the amm is on ~15 amps reading you install a temporal jumper wire between alt post and batt?

Is just an idea, but I’m thinking on a bad contact along the charging circuit on batt side causing a resistance requesting that new load. That jumper could discard a batt issue if the amm keeps around same reading with the jumper wire?

As mentioned I’m just thinking out loud. I might be wrong

Next, could be disconect the power windows and top relays to check if there is some draw there!

That’s actually not a bad idea. I had a buddy of mine suggested just the same exact thing ….piece of 10 gauge between the two.

As an update, I removed every fuse and disconnected a lot of accessories via plugs obviously, some of the amps went down, not
Much..I put them back in one by one and none of them caused excessive drainage. What I do see is 5 A across the ballast resistor with just the key on ( not running) using my clamp on amp meter

That 5 a goes thru the points When it breaks it goes away

 

[twecomm]

The current draw for a typical OE oil filled coil is in the 3-5 amp range and vary depending on specific coil type and coils recommended ballast resistor, so what you are seeing seems normal. With key on, the ballast resistor is electrically in series with the coil as you see measuring at ballast resistor. The ignition switch, when in cranking, or start position, electrically bypasses the ballast resistor delivering full battery volts to the coil for a hotter spark while cranking.

 

[BDnFL]

The OP indicates in post 5 he is using a clamp-on ammeter to break down where current is flowing. I would clamp that ammeter to the power lead to the top switch, or disconnect the top switch to eliminate that circuit as drawing the extra current not accounted for in the measuring so far.

I missed the clamp on part

 

[bandit67]

As an electrician, I have used clamp ons for amp metering for many, many years at the plant. I have total faith in using them for all levels of AC current feeds. But do not trust them for low level DC feeds. Im sure they have improved by todays standards, but I would install a second manual meter in the line temporarily somewhere to verify actual current draw and your original and clamp on meters accuracy is correct.

 

[OCTAVIOUS]

w

As an electrician, I have used clamp ons for amp metering for many, many years at the plant. I have total faith in using them for all levels of AC current feeds. But do not trust them for low level DC feeds. Im sure they have improved by todays standards, but I would install a second manual meter in the line temporarily somewhere to verify actual current draw and your original and clamp on meters accuracy is correct.

Coal fired Power plant I&C/Electrical for 30 years


Easy enough