Nissan alternator install and Vems...battery light flickering when car is hot
07-20-2018, 11:06 PM
#1
Nissan alternator install and Vems...battery light flickering when car is hot
So installed Vems, new turbo, headgasket, bottom rod bolts, Nissan alternator, ect. The car is running good, (even though my wastegate keeps opening cause of weak spring in wastegate which i am resolving. But that’s a different story.)
Anyway. When the car is cold the voltage is like 13.5-14.5 volts. When it is run for a while the battery light and “!” Light start to flicker. I check the voltage at the battery again and the voltage is about the same when car is warmed. Don’t know if this is a voltage regulator issue in the Nissan alternator? Or if this is normal cause the new alternator is more efficient more volts? Or cause of Vems? What do you guys think? And is there anyway to shut those lights off, if there is no issues of course, though VEMS? Help on this matter would be appreciated. I’m so close to finishing this build and now this annoyance.
Anyway. When the car is cold the voltage is like 13.5-14.5 volts. When it is run for a while the battery light and “!” Light start to flicker. I check the voltage at the battery again and the voltage is about the same when car is warmed. Don’t know if this is a voltage regulator issue in the Nissan alternator? Or if this is normal cause the new alternator is more efficient more volts? Or cause of Vems? What do you guys think? And is there anyway to shut those lights off, if there is no issues of course, though VEMS? Help on this matter would be appreciated. I’m so close to finishing this build and now this annoyance.
07-20-2018, 11:17 PM
#3
09-19-2018, 06:51 PM
#5
So just got the car back from it’s build/tune. Car is running strong. But the battery light remains. When the car is cold, it doesn’t come on. Only when car warms up. The voltage is 13.7-14.6 depending on if AC is on and/or fans. And yes it is the same at the battery and alternator posts. My one buddy said a ground somewhere. But where? In the instrument cluster? Or a diod somewhere.
Its anoing cause it lights up the “!” Too. 😐
Its anoing cause it lights up the “!” Too. 😐
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09-20-2018, 01:53 AM
#8
Burning Brakes
"Have you disconnected the battery when the engine is running and warm?"
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
09-20-2018, 05:15 AM
#9
"Have you disconnected the battery when the engine is running and warm?"
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
09-21-2018, 04:49 PM
#10
"Have you disconnected the battery when the engine is running and warm?"
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
While I have done this without damage to the electrical system, Porsche's Service Manual strictly cautions against disconnecting the battery while the engine is running. Do this at your own risk.
For those of us who like to gamble, this quick test will tell you if the alternator is putting out enough current to operate the car's electrical demands, i.e. if you disconnect the battery and the car stays running, then the alternator is OK (probably, not absolutely).
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
09-22-2018, 10:12 PM
#11
Burning Brakes
Don't measure the resistance of the wire, measure the voltage drop while you have the car running and accessories turned on, it's a more realistic, real-life test.
Mos DVM's don't measure resistance that low very well.
Mos DVM's don't measure resistance that low very well.
09-23-2018, 06:01 AM
#12
ok. So measure the resistance of the two points (bolt on body to the negative post) when the car is running with all the accessories on and then when the car off?
09-23-2018, 01:48 PM
#13
Burning Brakes
No, measure the voltage drop on the small wire.
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
09-23-2018, 01:56 PM
#14
No, measure the voltage drop on the small wire.
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
P.S. Test the smaller wire going from the negative terminal to the side of the firewall that the other end of the wire attaches to a bolt with all of the car's lighting and accessories on. This will be the smaller wire coming off the negative terminal. If you set your multi-meter to 20 VDC and put the black lead on the negative battery terminal, and the red positive lead on the bolt that the wire attaches to, you should read a very low voltage, the lower the better. This test will tell you how much voltage is being dropped over the ground wire. This #2 wire often gets green corrosion (copper) from moisture and the resistance goes up causing the voltage drop to increase. Anything over .25 VDC (yes, 1/4 of a Volt) indicates the wire has too much resistance and should be replaced. This #2 wire is the ground connection for everything that is not attached directly to the engine block.
09-23-2018, 08:40 PM
#15
So here is a comaparason from ground to negative terminal as instructed:
Voltage cold motor NO accessory (battery light NOT on) .012v
Voltage cold motor ALL accessories on (Battery light NOT on) .050v
Voltage hot motor NO accessories on (battery light flickering) .013v
Voltage hot motor ALL accessories on (battery light flickering) .052v.
So I don’t see much of a difference. And not much difference when motor hot and cold.
I also notice, that when the rpm’s are increased the battery light usually goes off. When the motor slows down, battery light comes back.
Voltage cold motor NO accessory (battery light NOT on) .012v
Voltage cold motor ALL accessories on (Battery light NOT on) .050v
Voltage hot motor NO accessories on (battery light flickering) .013v
Voltage hot motor ALL accessories on (battery light flickering) .052v.
So I don’t see much of a difference. And not much difference when motor hot and cold.
I also notice, that when the rpm’s are increased the battery light usually goes off. When the motor slows down, battery light comes back.