dual port alternator ?

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mfee2079
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dual port alternator ?

Post by mfee2079 » Sun May 24, 2015 7:44 pm

I picked up a project trike using a dual port 1600 (1973?) Motor, there are no numbers on the motor that I have found except on the case half's. There are two terminals on the alternator one says B+ which is battery, the other is a male spade connector inside a black square what is this connection for? Also is this internally regulated or will I need a regulator? Sorry if these are stupid questions, this is my first experience with vw motors.

jhoefer
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Re: dual port alternator ?

Post by jhoefer » Mon Jun 01, 2015 11:33 am

If it's just a single spade terminal, it's internally regulated. That is D+ and must go to the charge warning light (2 watt, incandescent) in the speedometer/dash. That terminal must be connected properly for the alternator to charge. That warning light also turns on if the fan isn't spinning, so it's pretty important.

mfee2079
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Re: dual port alternator ?

Post by mfee2079 » Mon Jun 01, 2015 11:40 am

I hooked up the light to a switched 12 v. Problem is light is on when running. Sign of a bad alternator?

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Marc
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Re: dual port alternator ?

Post by Marc » Mon Jun 01, 2015 12:32 pm

Assuming it's wired correctly, if the warning light is on the alternator is either putting out too little or too much voltage (the light bulb has no brains, it's only comparing the D+ voltage to that supplied through the ignition switch). For instance, if the wiring to the "hot" side of the ignition switch was inadequate for the loads placed on it, that'd drag down the supply side to the point where the D+ signal had a higher value and the light would come on even if the alternator was working fine.

If the alternator's been inactive for a long time it'll have lost any trace of residual magnetism to get the party started - that's where the "field flash" current coming through the warning lamp filament comes in. Sometimes it just takes getting the RPM up briefly; if that doesn't do it the internal regulator may be the problem, but it's as least as likely that the field brushes aren't making good contact with the slip rings. The copper slip rings may be contaminated and/or the brushes may be worn to the point where they don't seat well. IMO that's probably as far as you want to delve into repairing it yourself; by the time an alternator's got enough miles on it that the brushes need replacement there's a good chance that the bearings won't be lasting much longer, and new/rebuilt alternators aren't all that expensive.

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BTW, you may find references to "polarizing" ....pay them no mind, that procedure is for use only on generators, and does nothing constructive for an alternator.

mfee2079
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Re: dual port alternator ?

Post by mfee2079 » Mon Jun 01, 2015 5:58 pm

Thank you that's exactly how I have it wired. The alternator is bad, I removed the battery wire while running and voltage dropped at the B+ terminal to 1.3v. The problem is I have no clue how long this set up has been sitting and whether or not it was covered.
It has oil pressure and runs and idles perfect. I was scared to death firing it up for the first time. I was afraid of a bad rod or other mechanical nightmare, the same thing does not even smoke. Now I see why people swear by air cooled vw motors. Priced out a new alternator and those very inexpensive so that's what I'm going to do. There is too much other work to waste time trying to rebuild it when for all I know its original and has 200000 miles on it

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Marc
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Re: dual port alternator ?

Post by Marc » Mon Jun 01, 2015 6:14 pm

mfee2079 wrote:...The alternator is bad, I removed the battery wire while running and voltage dropped at the B+ terminal to 1.3v.
At 1.3v you wouldn't have gotten it to crank over, so I'll presume you meant 10.3v. Still a chance that the alternator might be salvageable with attention to the slip-rings/brushes, or a new regulator, but a new/rebuilt one definitely simplifies your life and gives you fresh bearings and a warranty

NEVER a good idea to lift the battery cable on an alternator setup. Removal of the reference voltage can cause the output voltage to skyrocket and smoke the diodes. An "OK" test for a generator, but it should be avoided with an alternator.

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