Charging Problem Revisited, Everything Swapped Options

[Allan]

Okay, been having a charging problem for awhile now. Started replacing and checking over everything. So far I've replaced the voltage regulator, relay board and now finally replaced the alternator and harness. Guess what??? No freaking charge to the battery. (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

Any ideas????????????????????????

[lapuwali]

Could be the "new" VR is also bad. This apparently happens a lot with Bosch VRs.

Here's how this all works:

The alternator generates AC current by spinning a coil of wires inside another coil of wires. The stationary coils are electromagnets initially energized by the battery. The current for this runs through the ignition switch and the G bulb, which is why the light is on with the engine off/switch on. Once the spinning coils get going fast enough, they're generating their own current into the battery, which is throttled by the voltage regulator. The voltage between the two terminals on the G bulb will then go to zero, so no current flow, so the bulb goes out. The alternator electromagnets are now "self-energizing".

If the bulb comes on while the engine is running, there's a voltage imbalance across the bulb, so the voltage is high or low on one side (battery or alternator) relative to the other. The causes for this are:

alternator is generating less than 12.5v (the "rest voltage" of a good battery)
the VR is holding the generated voltage below 12.5v
the battery is horked (esp. if it's internally shorted)
there's a short to ground between the G bulb and the alternator (no fuse here, and the bulb should be bright)

The battery should show 12.5v across the terminals with everything disconnected. If not, try slow charging it for awhile. If that doesn't get it back up there, replace the battery.

Test the "new" alternator and VR. New Bosch VRs seem to be bad in the box distressingly often these days. Rouser knows the part number of a solid-state Borg-Warner VR that's much more reliable. Do a search here for it (recent discussion).