ammeter readings (1 Viewer)

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Beckley

Beckley

Joined
May 25, 2019
Threads
13
Messages
111
Location
Prospect Ky
I am not sure if I have a problem or the reading is normal. When at idle speed it reads correctly. When I speed up it goes up to 30 amp (1978) which is pegged and stays there until I turn on radio, put fan at high speed etc. Even then it still reads way high. I just put on a new voltage regulator and have an almost new battery. I this normal? thanks for any advice
 
If you put a battery tender on the battery and know it is at full charge does it act the same? Even with a new battery, it may not be at full charge which the alternator/voltage regulator is detecting.
 
Yes. Can this cause problems in the electrical system? Where are you in Ky. I am in Louisville
 
Why did you replace the voltage regulator? Was the old one acting the same? Did the problem start when you replaced it? Can you post pics of the alternator, regulator and their connections?
 
With a charged battery and the engine running with no heavy-draw accessories on, the ammeter needle should be at or near zero. If it's remaining at plus 30 at speed something is up. If it only started after you installed the new regulator that would seem to point to a culprit.
 
It is reading perfectly at idle, then when speeding up the engine it goes up and stays at around 30. Its like I have a dead battery which I don't. Anyone know the readings that should be coming out of the voltage regulator and what color wires? I may need to call the people I bought the regulator and hope they have the answer CCOT
 
Do you have a voltmeter ? If so, measure battery voltage when you go to a higher rpm and see what that says.
 
1969FJ said:
Do you have a voltmeter ? If so, measure battery voltage when you go to a higher rpm and see what that says.
Click to expand...
That goes up also to about 18+ volts then stops. Doesn't go any higher. I put in the old volt reg again and it acts the same as the new one. They could both be bad. The new one looks different than the old one but is from a cruiser shop so I am assuming its correct. The plugs match up.
 
Beckley said:
That goes up also to about 18+ volts then stops. Doesn't go any higher. I put in the old volt reg again and it acts the same as the new one. They could both be bad. The new one looks different than the old one but is from a cruiser shop so I am assuming its correct. The plugs match up.
Click to expand...

That is way to high and problems will certainly happen. A normal alternator output is 13.5 to 15 volts. No higher. Your charging circuit something is wrong. Another test is to check the battery again, but using the AC test position. What you look for here is AC ripple. The alternator converts AC , (hence alternator), to DC. So, if there is AC present the alternator is bad.

The Normal Alternator Output Voltage

An automotive alternator generates electrical power to run the engine and charge the battery. An alternator that is putting out a reduced charge will eventually cause the engine to stall and not properly charge the battery, which can cause starting problems.
itstillruns.com itstillruns.com
 
1969FJ said:
That is way to high and problems will certainly happen. A normal alternator output is 13.5 to 15 volts. No higher. Your charging circuit something is wrong. Another test is to check the battery again, but using the AC test position. What you look for here is AC ripple. The alternator converts AC , (hence alternator), to DC. So, if there is AC present the alternator is bad.

The Normal Alternator Output Voltage

An automotive alternator generates electrical power to run the engine and charge the battery. An alternator that is putting out a reduced charge will eventually cause the engine to stall and not properly charge the battery, which can cause starting problems.
itstillruns.com itstillruns.com
Click to expand...




Its's showing 34 to 35 volts on AC setting. It sounds like you finally discovered the problem? Many thanks!
 
Is that .35 volts? If you are seeing 35.0 actual AC volts at the battery, either you meter is one that does not show true RMS values or something is really wrong.
Weird you have AC showing which usually indicates a bad diode, but you have high output voltage which points to a bad regulator. Normally a bad diode causes the output current to be lower resulting in dim lights.
 
Coolerman said:
Is that .35 volts? If you are seeing 35.0 actual AC volts at the battery, either you meter is one that does not show true RMS values or something is really wrong.
Weird you have AC showing which usually indicates a bad diode, but you have high output voltage which points to a bad regulator. Normally a bad diode causes the output current to be lower resulting in dim lights.
Click to expand...

I actually thought the same thing. Even 350 millvolts is to much ripple output from an alternator. I really do not know what could cause 35 AC volts ?
 
Last edited:
Beckley said:
Its's showing 34 to 35 volts on AC setting. It sounds like you finally discovered the problem? Many thanks!
Click to expand...


NOPE!
I also tested the meter inside the house on an electrical receptor and it showed 125 V. on both meters. I have retested the battery with car sitting , not started, and it shows 27.4 AC volts. I used two meters and it read the same on both. Then.....I tested another car I have and it tested the same under the same circumstances. It also showed 27.? on both meters. Now I am really confused. Now I know I have a good battery and good voltage regulator but too much DC voltage running around the circuit. Any other tests I can run on the alternator? It has a green 3 stud connector. |
 
1969FJ said:
That is way to high and problems will certainly happen. A normal alternator output is 13.5 to 15 volts. No higher. Your charging circuit something is wrong. Another test is to check the battery again, but using the AC test position. What you look for here is AC ripple. The alternator converts AC , (hence alternator), to DC. So, if there is AC present the alternator is bad.

The Normal Alternator Output Voltage

An automotive alternator generates electrical power to run the engine and charge the battery. An alternator that is putting out a reduced charge will eventually cause the engine to stall and not properly charge the battery, which can cause starting problems.
itstillruns.com itstillruns.com
Click to expand...


I also tested the meter inside the house on an electrical receptor and it showed 125 V. on both meters. I have retested the battery with car sitting , not started, and it shows 27.4 AC volts. I used two meters and it read the same on both. Then.....I tested another car I have and it tested the same under the same circumstances. It also showed 27.? on both meters. Now I am really confused. Now I know I have a good battery and good voltage regulator but too much DC voltage running around the circuit. Any other tests I can run on the alternator? It has a green 3 stud connector.
 
Beckley said:
NOPE!
I also tested the meter inside the house on an electrical receptor and it showed 125 V. on both meters. I have retested the battery with car sitting , not started, and it shows 27.4 AC volts. I used two meters and it read the same on both. Then.....I tested another car I have and it tested the same under the same circumstances. It also showed 27.? on both meters. Now I am really confused. Now I know I have a good battery and good voltage regulator but too much DC voltage running around the circuit. Any other tests I can run on the alternator? It has a green 3 stud connector. |
Click to expand...

You mean to tell me with the car engine not running, you read AC volts on the battery. Is this vehicle stock ? With the key off and engine not running there is basically nothing to generate AC, let alone present itself to the battery. Unless there is something on the vehicle we do not know about.
 
Puzzles the heck out of me also. I used 2 different meters and put them both on 2 different cars. Thats why I am totally confused. One reading was on my 1964 corvette and the other on my 78 FJ40. I don't know why any AC volts would measure at all. By the was, both read about 12.8 DC volts.

If you get a chance, I would love to know what the AC voltage on your battery reads. This is really confusing me.
 
Marn0 said:
Are you sure the meter is not auto ranging and is actually displaying millivolts?
Click to expand...

The meters show AC next to the number but I am not familiar with what you mean by ranging. All I know is that I am using two different meters and getting the same numbers. But, from everything I know a battery can't put out AC volts.
 
Marn0 said:
Auto ranging meaning that it automatically changes scale from millivolts to volts depending on what it is reading at the time
Click to expand...
I'll pay attention to that possibility...thanks I have the meter set to 200 AC volts. Thats the lowest setting I have. Its a digital read out.
 
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