Low Voltage after new alternator and battery

[sapote]

1. BST isn’t hot at all nor are the terminals. The wire itself is kinda hot but only an inch or so away from the BST.
2. Obviously can’t do the skin test on the part that goes through the car but where it connects in the engine bay is completely cool.

1. The BST housing is plastic so normally it's hard to feel hot here. The hot cable 1" away from BST -- this is not good. Either the cable to the BST crimp is bad, or someone had replaced the BST instead of the whole cable and didn't do a good job. This needs to be fix before the car is on FIRE.

2. The cable inside the rear C pillar and through the frame to the front fender is one piece and there is no need to check this section (unless someone had tried to splice two sections together.

[174bpm]

Sorry been a long day at work. The cable is definitely warm about 4 inches away, not 1 inch from the BST terminal after a 20 min drive. Not burning hot or melting anything. I’m the second owner of the car and have had it since 2008 so to my knowledge the BST has never been tampered with. I do understand the importance of this wire catching on fire and also that the cable shouldn’t even be getting warm. Replacing the cable is definitely something that I’m prepared to do if I can’t solve it with another new battery and alternator. Thanks again for the help 👍🏽

[ac427]

Or just measure the voltage from alternator body to the car frame -- should be less than 0.2v with engine running -- and this should reveal if the engine grounding cable issue.

Would you be measuring from the B+ post in the engine bay?

[sapote]

Would you be measuring from the B+ post in the engine bay?

As the suggestion to use the jumper cable: "Link one end to the earth point stud on the engine bulkhead and the other end to the engine. One of the lifting hooks will do.

Start the car. Was the engine more eager to start?"
This helps to bridge the engine to the chassis ground to verify if the engine grounding wire is bad or good. If the wire/connection is bad, then there is significant (a few tenth of volts or more) voltage drop from engine to chassis.

The alternative way as I suggest is to measure the voltage drop between engine/alternator to chassis during engine idling (or during cranking). So the measurement should be between alternator body (or engine) to the chassis, and the meter should display the voltage from chassis to engine as positive voltage. Ideally this voltage should be 0v if the engine to the chassis cable is perfect, and if the value is higher than 0v then it indicates the cable connection is bad.

Measure from B+ post to engine body can't tell the condition of the engine grounding cable. I.e. if the cable from alternator to starter and from starter to the B+ post is bad, then the measure will be lower, say 13.3v and so we can't blame this low voltage is caused by engine ground cable.

[ac427]

As the suggestion to use the jumper cable: "Link one end to the earth point stud on the engine bulkhead and the other end to the engine. One of the lifting hooks will do.

Start the car. Was the engine more eager to start?"
This helps to bridge the engine to the chassis ground to verify if the engine grounding wire is bad or good. If the wire/connection is bad, then there is significant (a few tenth of volts or more) voltage drop from engine to chassis.

The alternative way as I suggest is to measure the voltage drop between engine/alternator to chassis during engine idling (or during cranking). So the measurement should be between alternator body (or engine) to the chassis, and the meter should display the voltage from chassis to engine as positive voltage. Ideally this voltage should be 0v if the engine to the chassis cable is perfect, and if the value is higher than 0v then it indicates the cable connection is bad.

Measure from B+ post to engine body can't tell the condition of the engine grounding cable. I.e. if the cable from alternator to starter and from starter to the B+ post is bad, then the measure will be lower, say 13.3v and so we can't blame this low voltage is caused by engine ground cable.

Yes but isn't hard to get to the alternator connector without removing the airbox?

[sapote]

Yes but isn't hard to get to the alternator connector without removing the airbox?

Nowhere in the post I said to use the alternator connector (12v output):

"The alternative way as I suggest is to measure the voltage drop between engine/alternator to chassis during engine idling (or during cranking). So the measurement should be between alternator body (or engine) to the chassis"