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Fri Jun 03, 2005 9:45 pm

so my van's charging system does not seem to be working. the battery does not charge when the engine is running, but does not wear down while driving with my lights on. so for a little while i've been charging the battery on a weekly basis because it discharges the battery from starting only. any ideas??

...in case it matters the van is an 82 with a inline 1.8 from a jetta

Sat Jun 04, 2005 12:58 am

uh, 1of 4 things; batt, alternator, wires, or a drain. Check batt volt not running. Should be around 12 but may be lower in your case. Take note of it. Now check voltage with engine running. It should go up to about 14. If does not change at all then either alternator or it's wire is bad. If that is good then your alternator is good. You can check for a drain with ampmeter if it discharges after sitting a while. The batt may also be bad and not hold a charge.
Being that your jetta engine is probaly fuel injected and you had the lights on and it didn't die I would say alternator is working. Otherwise it would die. It may last quite a while if you have dual batteries though.

Sat Jun 04, 2005 5:53 am

Start it, pull the negative wire off the battery. If it stalls-bad alt.With the inline conversion many still have the 45 amp alt in it. Too weak to recharge a hurtin' battery. Also check the belt tension to the alt. If you can post a photo of your belt configuration so I can see it to look for problems.

Sat Jun 04, 2005 6:33 am

DON'T PULL THE WIRE OFF THE BATTERY while it is running.

The alternator will indeed fry in a diode of a second.

That is a old wive's tale Bill. You know better than that.

Sat Jun 04, 2005 8:00 am

forgot to mention. i have pulled the alternator and had it checked and have also had the battery checked and both are good. i can charge the battery with the charger and it takes a good charge. i can also run the vehicle with lights on and have full strength that does not diminish. but if i give the battery a quick jump (enough for 1 start)i can run the bus all day and the battery recieves no charge.

Sat Jun 04, 2005 8:39 am

I totally disagree. Pulling the positive will fry the alt, the negative has no effect, it mearly closes the circut. It is ground as is the alt. Trust me I've done it MANY times and never a fry. For a field test with no diagnostic tools that is the only way.

Sat Jun 04, 2005 9:00 am

More on this. With the conversion set up I've seen many different set ups. Sometimes the set up doesn't spin the alt fast enough to put out the amps necessary to charge the batt. Add an extra ground from the alt to the block,just to be sure.Is your alt a plug in or a direct wire?Seems like a bad wire on the charge circut.Conversions present many reconfiguration problems creating a whole new set of troubles.

Sat Jun 04, 2005 9:01 am

Bill W wrote: I totally disagree. Pulling the positive will fry the alt, the negative has no effect, it mearly closes the circut. It is ground as is the alt. Trust me I've done it MANY times and never a fry. For a field test with no diagnostic tools that is the only way.

Your owner's manual and all repair manuals will tell you to NEVER RUN THE CAR WITH THE BATTERY DISCONNECTED. It doesn't matter WHICH cable you disconnect- positive or negative- you're breaking the flow of current. Alternators are designed to work WITH a known good battery completing the circuit. PERIOD. DON'T DO IT.
You shouldn't be conducting a field test without diagnostic tools, anyway.
My best sceintific wild ass guess on this problem would be to suspect the grounding strap between engine/ trans and the body.

Sat Jun 04, 2005 9:07 am

I know but 1.8 inline dosn't use the brain the wassers do, nothing to kill. Ever have a completly dead battery? Did it kill the alt? same thing.

Sat Jun 04, 2005 9:25 am

Bill W wrote: I know but 1.8 inline dosn't use the brain the wassers do, nothing to kill. Ever have a completly dead battery? Did it kill the alt? same thing.
I'm just pointing out what the engineers and service experts put into print. I always say, when in doubt, consult the experts.
If you went to the dealer with a new car under warranty with a fried alternator, and there was ANY EVIDENCE that it had been run with the battery disconnected...guess what? YOU are buying an alternator!
72- 74 Busses didn't have any "brains" at all, and they STILL told you not to run the alternator with the battery disconnected. That went for all alternators.

Sat Jun 04, 2005 9:42 am

I concur that it shouldn't be run with battery disconnected. I have read that in many different service manuals. If both the alt and batt are definetely good and belt is not slipping then the problem would have to be in the wiring. Either the positive wire back to the battery or the engine ground. Again, this can be pinpointed with a multimeter.

Sat Jun 04, 2005 11:19 am

the van has run for 2 yesrs with no problems so i know its a question of something not working or coming disconnected. it has worked properly until recently

Sat Jun 04, 2005 9:28 pm

FWIW the battery acts like a sponge absorbing power spikes. Pulling off the battery cables when the van is running is a very nice way to blow out an ECM. Been there, done that, got the hat and t-shirt. Used to do that as a demo at school (work). Last car we fryed was a 97 Acura 2.2 CL. And I pulled off the NEG. cable. :roll:

Its much easier and safer to take a voltmeter and have the car running, and then load up the electrical system (headlights, wipers, fan, etc..) and see how far it drops at 2000 RPM. Better yet, use an inductive amp probe around the B+ wire of the alternator to see how many amps its putting out.

:idea: