charging question.

[kevinm]

I took the regulator off the alt. And then ran the car for a bit, maybe two minutes.. now with the regulator back in it won't charge the batt.. ive tried another working regulator and still no luck.. what happened?

[TylerDurden]

The diodes in the alternator may have blown from a voltage spike.


Any other details that might provide clues?... Like why remove the regulator? Did the battery get disconnected wile running?

[kevinm]

i thought i heard an old brush bouncing around in there... as i lost one in there a while back.  i took the reg/brushes out and revved her up thining something would bounce out.  No luck, probably in the bottom of the casting.  I just know its not charging at all now and the brushes/reg. are good .

[TylerDurden]

I'd get it tested.

Revving it without a regulator could shoot the voltage way up... more than the alternator may be damaged.

[CRSMP5]

but.... no brushes were installed...... so the rotor was not hooked up to the case when it was turning.... so how would diodes be powered?   

now if it was ac... no brushes in ac motor.. ok.. it be a problem..

differance in dc motor and a dc gen/alt is power out vs power in..

i guess spinning the coils up will create some sort of magnetic voltage thru the wire coils... but brushes and reg not installed so should be open..

just saying... yea i has ee degree too...

im going to guess some sort of static charge fried something due to lack of ground due to no reg...

[TylerDurden]

Yeah, it could still be a broken indicator/exciter wire.

OP:

Does the dash light come on?

[kevinm]

Dash light does not come on..  which it used to before 2k revs or whatever the number is. The car died after 15 minutes this morning. Bat was fully charged and I only had headlights on and blower motor on low. Major short in alt?

[TylerDurden]

Seems like an excessive load is on the battery and the alternator is not charging.

I would charge the battery, disconnect the D+ (blue) wire from the alternator and verify 1.5V at the wire with the key on (engine not running). That should indicate continuity through the wire.

If that tests OK, I'd take the alternator to a shop for a test.

[92EcoDiesel Jetta]

I don't think your alt was damaged from running it w/o a regulator. alt light/excitation circuit is completed through regulator brushes/diodes to ground in the alt. no regulator- no excitation- alt was off.

[TylerDurden]

That's what Chris was saying... no regulator = rotor current = no failure from overvoltage.

Alternator no workee, so... maybe residual magnetism in rotor generated current & high voltage. As likely as static, IMO.

OTOH, the OP reports losing a brush at some point... maybe the loose brush shorted a diode.

[kevinm]

Went to start the car after work with a freshly charged bat and it ran like it was on three cylinders.  Misfires then nothing.. this is my gas pot btw. 86 CISe.. ill keep you posted its now at the mechanic..

[92EcoDiesel Jetta]

My thoughts are the mis-firing is unrelated to your alternator issues. If you are not getting the alternator light (pre start), you are not getting excitation to the alt so you have to fix that first. The excitation is provided via a 300 ohm resistor in the cluster (actually 2 x 600 ohm resistors in parallel), NOT by the alt LED. Check for voltage at the blue (excitation) wire at the alt with key on. If you don't get any, cut the lug off, strip the insulation and check for voltage again.

[CRSMP5]

gas not diesel... so yes possible a electronic voltage issue screwin with the ignition.. get new alt..

to test dash led... you all work too hard... ground blue wire out = idiot light... no light.. look for broken wire/issue..

this same on temp/fuel gauges too... op lights... just ground out at where plugs in...

hot wire on alt... i even ground them to watch for welding ark... seen bad spots in that wire only that test finds.. will burn thru.. like a fuse.. very common on mk1 westy bunny...

[92EcoDiesel Jetta]

gas not diesel... so yes possible a electronic voltage issue screwin with the ignition.. get new alt..

to test dash led... you all work too hard... ground blue wire out = idiot light... no light.. look for broken wire/issue..

this same on temp/fuel gauges too... op lights... just ground out at where plugs in...

hot wire on alt... i even ground them to watch for welding ark... seen bad spots in that wire only that test finds.. will burn thru.. like a fuse.. very common on mk1 westy bunny...

He had a fully charged battery, how can electronic voltage issue screw with ignition? Battery is a very good voltage regulator.

I agree grounding the blue wire is a good and easy test of the wire and the alt LED.

Tell me more about grounding the hot wire on alt test.

[CRSMP5]

ok.. we already know he has a issue.. what if the wheat stone bridge screwed up.. it gets a phantom current that screws with the ignition modual.. ive seen some odd running issues on cars over the years.. and when those alt died the "odd" issue was fixed..

say for example, you have a mk2... the red wire goes from alt to starter post... where the wire bends at the starter, zip tied to the metal pipe... ive seen them corrode inside the red rubber... if you ground out the eyelet of the wire to the head, block, alt.. it should produce a sweet bang and spark... like you can weld... now if it goes pop with no spark.. that weak, corroded spot just blew out... like a fuse... replace wire..

now 81-84 bunny/caddy aka westy.. between the batt and fender well those 2 wires, the 2 running inside the cart, the 1 from batt join together in a crimped steel sleve wrapped up in tape in the harness.. it goes green.. car does odd things.. like will only run when you pull highbeam lever.. bypasses things so no explain that..

simple test.. bunny unplug.. stick screw driver in.. weld on alt case.. no weld, or pop with nothing.. got a bad spot.. it also good test to make sure the alts mounted in rubber bushings like old mk1s.. ground wire is good.. bad ground = no charge too.. now with no rubber bushing not a issue.. but again.. old tests for bunny and such..