Another Charging System Q

[jeffncs]

I have a 77 with a new Centech harness. To the best of my knowledge, the harness is wired 100% correct. I've been driving the truck around town to work out the bugs. After driving for a while (+/-30 mins), the truck dies.

What is the target alternator output? How do I test it?

How do I test the battery for proper charge and number of operating cells?

Both the alternator and battery are new with warranties...

Thanks.
Jeff

 

[TOFIC]

Talk to RRRRAAAYYY222 on this board. He is THE man for alternators.

 

[70_Steve]

What is the target alternator output? How do I test it?

How do I test the battery for proper charge and number of operating cells?

Quick test of the charging circuit. Start the engine, pop the hood and hook a mutimeter/DVM on the battery + and - terminals. With the stock charging hardware (alternator and voltage regulator) you will probably see around 12.7 to 13.0 volts at idle. Rev up the engine a bit, and you should see 13.8 to 14 volts.

Easiest way to test the battery is to take it somewhere. Most of the auto parts stores will test for free.

 

[AKwheeler]

Your description is lacking. When the vehicle dies does it still have power to operate items such as the headlights, fan or such? Starter cranks, but does not run? If it cools off does it restart and run?

If it dies and then doesn't start and no or little power anywhere check the battery voltage. If the battery is dead, charge it fully and then start testing the charging system.

If it dies, but cranks well, then look for spark and fuel and then start chasing the diag from there. I would be looking hard at the ignition control module. They typically fail after getting hot, then cool off and start working again.

Make sure you have good grounds. There needs to be one from the battery to the block and one from the battery (or block) to the chassis. Make sure they are free of rust and paint.

 

[jeffncs]

Sorry, I'm versed in general engine diagnosis, so I usually leave out the easy stuff. fuel and spark - perfect

The electrical items remain functional... It was strange the way it happened the other night. I was on my way back to the garage and it started to die after driving for about 15-20 mins. It was almost as though it was fuel-starved (definitely NOT the case). When it did finally die, lights and other accessories worked to the best of my knowledge. I hustled to the garage and brought my truck back for a quick jump. After ~1 min of being hooked up, she fired and ran long enough to get home.

I threw on the charger for a few mins Sat AM. She ran long enough to drive 2 miles to the exhaust shop and for them to maneuver it around the yard/shop. Restarting was a no-go when I went to collect her. A quick hit with the starter and she made it home. Thoughts?

 

[jeffncs]

I hooked up the slow charger for a couple hours this evening. I noticed one of the caps bubbling out water, so stopped the charger. The charger started out pegged in the "dead battery zone". When I pulled the plug, it was about mid-way across the span. This is a new battery and alternator.

I started the engine and tested some different points with a multi-meter. All numbers under idle conditions. The battery shows 12 volts. The output of the alternator show 12 volts.... Do these numbers look right?

I plan on getting the battery tested this week. Anything else I should check that I'm missing?

Thanks.
Jeff

 

[jeffncs]

Anyone have any suggestions?

Thanks.
Jeff

 

[bmc69]

I started the engine and tested some different points with a multi-meter. All numbers under idle conditions. The battery shows 12 volts. The output of the alternator show 12 volts.... Do these numbers look right?

Nope. That is about what the battery voltage would/should be if battery is reasonably well charged up and the alternator is not putting out anything.

As indicated above..your battery voltage with the truck off should read about 12.1- 12.3 or thereabouts. With the truck running you should see 13V, minimum, but more like 13.5, and even up to 14 (depends on which alternator you are running..my 140A Alterstart is 14V..stock Ford 60A alts are around 13.5-13.7), depending on what the battery is still taking as far as a charge current.

 

[mhandy]

when I worked at a Ford dealer in the late 70's they used to have a lot of problems with the module cutting out and acting as you describe. Believe it or not we used to pour cold water on them to cool them down to see if that was the problem

 

[bronko69er]

How old is the battery? I had similar symptoms recently and it was time for a new batt.
it would take a charge and all would seem right (voltage wiht engine off and on) after it was charged, but it couldn't put out the amps necessary to start.

 

[deltarat]

when I worked at a Ford dealer in the late 70's they used to have a lot of problems with the module cutting out and acting as you describe. Believe it or not we used to pour cold water on them to cool them down to see if that was the problem

I put a bag of ice on mine to get back home in my LTD one time.

 

[jeffncs]

The battery and alternator are both new.

I have a feeling those voltage readings are key to my problems. I think the alternator may not be putting off enough charge. I'm not seeing anything more than 12V at the alternator output when I expect to see more.

I'm going to get it tested tomorrow evening after work. It's all under warranty by the parts store.

Jeff

 

[DirtDonk]

Is it an externally regulated (original style) or internally regulated alternator? If external, don't forget to check the voltage regulator and the wires going to it. Even though they're new, you could have a bum connection with one of the wires as well.

Paul

 

[RRRAAAYYY2]

New battery and it is bubbling on a charger? I would be really skeptical of it. No use testing anything for voltage until you are starting out with a battery that is sitting with 12.7volts or more in it. After that when running it should climb to over 13.8 (working hard) to 14.5 (all is good) volts.

My first impression is you have issues with the battery.

 

[jeffncs]

Update

I took my truck over to the parts' store to test the charging system and battery. He states the battery is hitting the target voltage using his tester. However, the tester ID'd the alternator as not charging adequately....

I have a replacement alternator to install tonight. My question - anything else I should look at? Voltage regualtor? Any other connections that require inspection?

Another dumb question, which terminal do I hook the skinny wire to? There are 5 posts on the rear of the alternator. The red connection is obvious... Do I use the Field post (white),the black post or one of the unmarked posts?