Quick question:
Can a bad alternator that is still hooked up to a car that is not running cause the electric system to be totally dead and cause a battery charger to spike off the amperage scale and then cycle off?
Background:
2005 Lexus GX470 with 123,000 miles.
Battery is 60 months old (84 month high quality).
While driving a few nights ago, I heard the strangest moaning/whining sound that changed like a belt noise but was unlike any belt noise I have ever heard. About 15 minutes later the dash “battery discharge” warning illuminated. I checked that the belt was turning and noticed an odor like burning electrical components or brushes. I made it home OK about 20 mins later. Based on things at that point in time, I was all ready to replace the alternator.
3 days later, a friend (now former friend) with some auto repair experience was over and offered to troubleshoot my electrical system. The rig started OK. While my friend was listening to the alternator noise and making sure the belt was OK, I went to grab my voltage meter to check the battery and alternator output. As I approached the rig that was still running, my former friend said he could check the alternator real quick and proceeded to remove the positive (yes, the positive!) cable off the battery!! The rig quickly stopped.....
When he hooked the positive cable back up, the entire electrical system was DEAD. When I put a voltage meter on the battery while it was hooked up to the GX, the voltage was 0.1V. When I took the negative terminal off the battery, the voltage increased to 11.8V. I hooked up the negative cable again -> voltage = 0.1V.
I then hooked a battery charger up to the system with the battery cables on: amperage on the charger spiked and the charger cycled off. I then took the negative cable off the battery and connected the charger to the battery - things worked just fine. I charged battery up to >12V, hooked back the terminal cables -> no electricity in rig.
I then disconnected the alternator -> power back to rig and the battery charger works when battery hooked up to the system.
I checked the alternator with an ohm meter (I don't have a diode checker):
-> red wire to alternator case, black wire to alternator main terminal -> very low resistance (close to 0 on an analog needle).
-> black wire to alternator case, red wire to alternator main terminal -> very low resistance (close to 0 on an analog needle).
I have not yet tried to start the vehicle, but lights, dash, nav system, all seem to work (I was afraid that my former friend fried one or more computers or other components).
My plan is to fully charge the battery with my battery charger, then find someone who can check the battery for me to make sure the battery is not contributing to the problem.
Despite the fact that I can't find any similar to my story on the internet, it sure seems to me that the alternator is bad and "shorting out" the electrical system when it is connected.
Have anyone ever heard of this situation?
Does anyone think my former friend fried the alternator (that was already bad) or just coincidental?
Does anyone think my battery is OK or did it get fried as well?
Does anyone have any other explanation?
Because I am naive and curious, I decided I should, for the first time, try to check to see what kind of background draw my electrical system has with a current meter. Without thinking about the status of any system that might be trying to reboot after the battery was disconnected, and not remembering how long I had the battery hooked up before I removed the negative cable, I checked current flow between negative terminal and negative battery cable - my meter was set at 250mA and the needle spiked and blew the fuse in the multimeter. This concerns me a lot, but clearly I don’t know what I am doing, but at least for the next few weeks I am mostly on my own without any local expertise to assist and I don’t want to do anything stupid moving forward
Thanks for listening and for any thoughts you might have.
Can a bad alternator that is still hooked up to a car that is not running cause the electric system to be totally dead and cause a battery charger to spike off the amperage scale and then cycle off?
Background:
2005 Lexus GX470 with 123,000 miles.
Battery is 60 months old (84 month high quality).
While driving a few nights ago, I heard the strangest moaning/whining sound that changed like a belt noise but was unlike any belt noise I have ever heard. About 15 minutes later the dash “battery discharge” warning illuminated. I checked that the belt was turning and noticed an odor like burning electrical components or brushes. I made it home OK about 20 mins later. Based on things at that point in time, I was all ready to replace the alternator.
3 days later, a friend (now former friend) with some auto repair experience was over and offered to troubleshoot my electrical system. The rig started OK. While my friend was listening to the alternator noise and making sure the belt was OK, I went to grab my voltage meter to check the battery and alternator output. As I approached the rig that was still running, my former friend said he could check the alternator real quick and proceeded to remove the positive (yes, the positive!) cable off the battery!! The rig quickly stopped.....
When he hooked the positive cable back up, the entire electrical system was DEAD. When I put a voltage meter on the battery while it was hooked up to the GX, the voltage was 0.1V. When I took the negative terminal off the battery, the voltage increased to 11.8V. I hooked up the negative cable again -> voltage = 0.1V.
I then hooked a battery charger up to the system with the battery cables on: amperage on the charger spiked and the charger cycled off. I then took the negative cable off the battery and connected the charger to the battery - things worked just fine. I charged battery up to >12V, hooked back the terminal cables -> no electricity in rig.
I then disconnected the alternator -> power back to rig and the battery charger works when battery hooked up to the system.
I checked the alternator with an ohm meter (I don't have a diode checker):
-> red wire to alternator case, black wire to alternator main terminal -> very low resistance (close to 0 on an analog needle).
-> black wire to alternator case, red wire to alternator main terminal -> very low resistance (close to 0 on an analog needle).
I have not yet tried to start the vehicle, but lights, dash, nav system, all seem to work (I was afraid that my former friend fried one or more computers or other components).
My plan is to fully charge the battery with my battery charger, then find someone who can check the battery for me to make sure the battery is not contributing to the problem.
Despite the fact that I can't find any similar to my story on the internet, it sure seems to me that the alternator is bad and "shorting out" the electrical system when it is connected.
Have anyone ever heard of this situation?
Does anyone think my former friend fried the alternator (that was already bad) or just coincidental?
Does anyone think my battery is OK or did it get fried as well?
Does anyone have any other explanation?
Because I am naive and curious, I decided I should, for the first time, try to check to see what kind of background draw my electrical system has with a current meter. Without thinking about the status of any system that might be trying to reboot after the battery was disconnected, and not remembering how long I had the battery hooked up before I removed the negative cable, I checked current flow between negative terminal and negative battery cable - my meter was set at 250mA and the needle spiked and blew the fuse in the multimeter. This concerns me a lot, but clearly I don’t know what I am doing, but at least for the next few weeks I am mostly on my own without any local expertise to assist and I don’t want to do anything stupid moving forward
Thanks for listening and for any thoughts you might have.
