| Re: Need some electrical smarts. |
Subject: Re: Need some electrical smarts. by donhall on 2016/4/8 13:10:21 Paul, the following message is the response received from my EE friend: "Ammeters don't lie. Some electrical circuit in the car is conducting 19 amps from the positive terminal to ground and is the reason for the spark on the wrench when it touched ground. The wrench must have touched the neg bat terminal, AND then ground (the metal hold down bracket). Here is a situation where I love my clamp-on DC ammeter which allows you to tell which wire is conducting leakage current without the dang bother of disconnecting each wire and using your DVOM!!! I bought a Sears clamp on dc meter with a discount coupon about a year ago for about $40 ($60 without the coupon, and the lowest cost clamp dc meter I know of). One circuit that I would look at first is the alternator to battery connection. This connection has a fusible link, not an unpluggable fuse and 19 amps won't blow the fusible link. The alternator could have a blown rectifier diode and with the engine running the alternator could easily supply both battery charging current and 19 amps to ground through the blown rectifier. I would unbolt the large red wire on the alternator first, disconnecting the bat ground, and then reconnect the bat ground, and measure the current flowing between the large red wire, and the alternator terminal (engine off). If that isn't it, then you have to measure the current on every wire the bat positive term is connected to. The second wire I would test would be the starter motor large wire, if it isn't fused. Do the same procedure as the alternator wire. Third, would be the starter solenoid wire, if it too, is not fused. Owner has pulled all fuses, and leakage current still exists. Hope this helps." |
