Batteries / Alternator Diagnosis Help Please

[PinzVair]

Did some more checks today. The molex terminals were quite dirty, however conductivity through the connector was quite good (micro-Ohm ranges). I did some more voltage checks to see what up. Anyway while I mull this over a bit.

Would you electric folk agree that this is applicable to how the voltage reg works in the Pinz?

http://www.ehow.com/how-does_5024418_au ... -work.html

[Jimm391730]

Yes, that is a basic description of how the voltage regulator works. But in most "modern" vehicles (Pinz included) the regulator does not "turn off" the alternator but rather turns down the amount of amps that it produces by weakening the field (the rotating part of the alternator that is fed by the slip rings). If the alternator is putting out more current than the vehicle is using, the extra current goes into charging the battery. If the alternator is putting out less current than the vehicle is using then the battery starts getting drained. So the regulator aims to keep the battery at about 13.8V (27.6V in a Pinz) which would be fuly charged. The alternator output increases or decreases as addtional loads (lights, fans, etc.) are switched on or off.

[PinzVair]

Well I took the batteries down to Autozone and they tested ok on the load meter. One battery was too low to test so they put them on the charger for me. When we picked the batteries up the lady said they had tested good... I'm suspicious of that.

I put them back in and it does crank better but... the VOM is still showing just over 12v and 11.8v. Just to satiate my curiosity I put the same VOM on the battery in my pickup and it read at about 14.5v so I really don't think the batteries are doing thier job 100%. Still curious as to what the alternator is doing... maybe I'll take it over and have the alternator tested too.

I've cleaned up the "molex" connector and the resistance through it looks good and low (like almost nothing). I'm working on another video so you can see what I'm doing and what I'm reading.

[PinzVair]

Latest update video on the voltage readings and results...

http://www.youtube.com/watch?v=ROdCRfhwMS8

[Jimm391730]

OK, so you got about 60 volts at the distributor end of the red wire, but only 24.1 volts at the molex end? This means the red wire is open (broken, disconnected, whatever) so that the voltage/current from the alternator is NOT getting to the molex connector end of the wire.

With the engine off, unbolt the red wire from the alternator. You should measure less than 1/2 of an ohm from end to end (really much less than 1/50 of an ohm but typical VOMs won't go that low). Either the cable itself is burned open inside (rather unlikely, unless it is a "fusible link" wire [and I'm not certain what fusible links Steyr used]) or the connection at the alternator side of the Molex is so corroded that there is no connection. You need to completely REMOVE both sides of the Molex and carefully examine the crimps between the wire and the connector (this is what usually goes bad). You really can't tell without removing it. You may even need to use a pin to push the locking tab out of the way and pull the metal connector from the plastic housing to fully examine the crimp.

I'd give it a 30% chance that the wire is a fusible link that has opened (a fusible link is a wire designed to be a fuse, and not carry current if the current value somehow goes too high) and a 70% chance that the crimp is corroded away so the wire conductor is no longer connecting to the metal of the connector (and I'll give you a 100% certainty that the wire/connector continuity is bad, as shown by your voltage tests). You can shortcut the process by connecting another heavy wire (remember, the alternator is rated for 35 amps, so use at least a #10 AWG sized wire) between the alternator terminal and the distributor side of the Molex red wire and I'll give odds that your batteries will show some amount of charging; it depends on if the alternator rectifiers have been damaged by the lack of connection - they were never designed to have 60-70 volts across them (more voltage if you rev the engine - don't do it!). Best guess is that they just might be OK, based on your 60-70V reading at the alternator terminal. So if your battery voltages get up towards 13-14 volts each then you have solved the lack of charging problem; fix the wiring/Molex and all should be well. If the batteries get over 14.5 volts then the voltage regulator needs replacing (relatively cheap, under $50?).

Some people have eliminated the Molex connector completely, and ran wires directly from the alternator to wherever the wires go on the other side of the Molex. I wouldn't go that far; I've just replaced the alternator side of the Molex (around $30 IIRC?). Fixing the Molex is relatively simple, relatively low cost, and easy to maintain/prevent any issues from appearing in the future (just give the crimps and connections a liberal coating of DeOx compound or even plain grease to exclude water and air from corroding them). Fix it right and it will last for years.

Let us know if this solves your problem.

[PinzVair]

Awesome! Thanks Jim I'll give all that a good shot and get back with some results!

[PinzVair]

I think I've figured it out. Jimm nailed it about the fusible link wire being bad. When I drop a current across it or when I attempt to measure resistivity I get the same results - OPEN CIRCUIT... not even M-Ohms. Going to do a quick bypass with a #10 wire and see what happens.

[PinzVair]

Well... today I drove the Pinz a total of 50 some odd miles. No charging issues and it started every single time. Too bad I didn't have my cameras when I got up into the mountains. OUTSTANDING SUNSET UP THERE! Will probably go again soon as I found the dirt-bikers pit to be vacant, muddy, bumpy, and a hell of a lot of fun

[Jimm391730]

Excellent! Glad you got it fixed. Put a voltmeter in somewhere to keep an eye on the charging condition. I got some small LCD voltmeters that only use two wires, black and red. They self power from 3V up to 40V and give the voltage to a tenth of a volt, and are fast enough to show the voltage while cranking. I just wish they were backlit for night time visibility.

[PinzVair]

Excellent! Glad you got it fixed. Put a voltmeter in somewhere to keep an eye on the charging condition. I got some small LCD voltmeters that only use two wires, black and red. They self power from 3V up to 40V and give the voltage to a tenth of a volt, and are fast enough to show the voltage while cranking. I just wish they were backlit for night time visibility.

Where did you get those?

[krick3tt]

Yeah Jim,

Where did you get those. Been looking for something like that, even if they are not lit.

Morris

[Jimm391730]

These are available from Digikey (http://search.digikey.com/us/en/product ... -ND/385409) and here is the datasheet for them: http://www.martelmeters.com/pdf/QM_100V.pdf

They are $46 each from Digikey, but I've got a few that I'd sell for $30 (may have been hooked up at one time). They fit very nicely in the dash hole where the tripmeter reset knob goes (if you have an electronic speedo, this hole is empty) but would also fit just about anywhere including the blank cover for the tach hole.

When they are attached to the wiring under the dash you will get a few tenths of a volt drop when the headlights turn on, but it is still very obvious that the truck is charging. You could run leads all the way to the battery but I did not find this level of accuracy that important.