S5 alternator charging too much?
11-18-11, 07:22 PM
#1
The General RE
Thread Starter
S5 alternator charging too much?
I was having a problem with low charge voltage. I replaced my corroded 10Ga charge wire with 2x8Ga wires. My Lm1 is reading a battery voltage of 14.6v now. Good. My Microtech is reading 15.4v now. High. Voltages are both very stable, but 15.4v has me a little nervous.
The way things are wired. Optima battery in the trunk. Lm1 wired to the battery. 2-0Ga wire is connected from the battery to the started positive lug. 2x8Ga wires connect to a distribution block from the starter lug. The Microtech power lead and other accessories in the engine bay vicinity are wired to the distribution block. The alternatcones connected to the distribution block with two 8Ga charge wires. The alternator's charge sense wire is connected directly to the alternator charge post.
Does anyone see a problem here?
The way things are wired. Optima battery in the trunk. Lm1 wired to the battery. 2-0Ga wire is connected from the battery to the started positive lug. 2x8Ga wires connect to a distribution block from the starter lug. The Microtech power lead and other accessories in the engine bay vicinity are wired to the distribution block. The alternatcones connected to the distribution block with two 8Ga charge wires. The alternator's charge sense wire is connected directly to the alternator charge post.
Does anyone see a problem here?
11-18-11, 07:37 PM
#2
Driving RX7's since 1979
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If you're reading 15.4 volts, then your alternator regulator is toast. Wiring can't raise voltage, but bad wiring can kill the regulator.
If you're reading 15.4volts with the car not running, so just battery volts, then you have a magic battery that is key to solving the energy crisis.
If you're reading 15.4volts with the car not running, so just battery volts, then you have a magic battery that is key to solving the energy crisis.
11-18-11, 07:56 PM
#3
The General RE
Thread Starter
If you're reading 15.4 volts, then your alternator regulator is toast. Wiring can't raise voltage, but bad wiring can kill the regulator.
If you're reading 15.4volts with the car not running, so just battery volts, then you have a magic battery that is key to solving the energy crisis.
If you're reading 15.4volts with the car not running, so just battery volts, then you have a magic battery that is key to solving the energy crisis.
Yes, it is 15.4v running. 12v off.
11-19-11, 08:31 AM
#4
Rotary Freak
Key on engine off. The small plug of the alternator plugged into the alternator.
The black/white wire of that plug should read batt voltage. The white/blue wire of that connector should read 1-3 vdc. That's with key on, engine off.
White/Blue is the excitation input to the alternators field and should be there. IF it reads batt voltage then the vr is shot in the alternator. Replace regulator.
The voltage on those two wires while connected to the alt, and the engine running.........is shown in the free online manual listed in this forums FAQ page. Engine Electrical section I think.
The black/white wire of that plug should read batt voltage. The white/blue wire of that connector should read 1-3 vdc. That's with key on, engine off.
White/Blue is the excitation input to the alternators field and should be there. IF it reads batt voltage then the vr is shot in the alternator. Replace regulator.
The voltage on those two wires while connected to the alt, and the engine running.........is shown in the free online manual listed in this forums FAQ page. Engine Electrical section I think.
11-19-11, 11:09 AM
#5
Rotary Freak
I screwed that up. The W/L should have batt voltage and the W/B should be the one with the
1-3 vdc with key On engine OFF. According to the online wiring manual on page Z-24 for series five cars.
1-3 vdc with key On engine OFF. According to the online wiring manual on page Z-24 for series five cars.
11-22-11, 04:27 PM
#6
The General RE
Thread Starter
Replaced the alternator with a remanufactured unit and I have a different problem now. Alternator won't charge at all (12V) until I rev it up over 3000RPM. Then it makes 13.7V +/- 0.5V. It creeps down with increasing operating time and temp. Is this a bad reman or another symptom?
11-22-11, 05:34 PM
#7
The White/Black wire at the back of the alternator has 1-3 volts w/key to on and engine off and has 12 volts w/engine running. You place a paper clip into the back of this plug to take measurements from using the multimeter. If it checks correctly under both conditions then it is likely a bad new alternator which occurs quite often. Also,make sure the belt is the proper tension.
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12-10-11, 08:29 PM
#8
The General RE
Thread Starter
I originally wired my alternator using the following diagram. I was confused as to what gets connected to the "L" wire. I had nothing connected because I didnt think I needed the warning light.
I found a thread on an Australian site with some RX3 specific information for alternator upgrades.
http://www.ausrotary.com/viewtopic.p...2c027fc15abf3f
They insist there should be keyed power and a diode to the "L". I just tried it and it seems to have worked.
"L" voltage reads 0v key off, 1.8v key on engine off, 12.9v key on engine on. Am I going to see any problems develope from wiring the alternator this way? Or did I finally get it right?
I found a thread on an Australian site with some RX3 specific information for alternator upgrades.
http://www.ausrotary.com/viewtopic.p...2c027fc15abf3f
They insist there should be keyed power and a diode to the "L". I just tried it and it seems to have worked.
"L" voltage reads 0v key off, 1.8v key on engine off, 12.9v key on engine on. Am I going to see any problems develope from wiring the alternator this way? Or did I finally get it right?
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