Battery, Alternator, or other electrical system problem

[usafdarkhorse]

UPDATE:

Alright, so I got the car back from the shop. They put in a new ground from the alt to the body. It seemed to run better, so they checked the voltages.

Apparently the alt is putting out 15V, but it's only getting 13V across the battery, so, due to liability reasons, they recommend ME to put in a cable that goes directly from the BAT connection on the alt to the positive side of the battery. A hotwire if you will.

I get home and do it. Big 4 AWG cable from the alt to the battery. Start it up. I get 11.9V across the battery, give it a rev or two, and it settles around 12.5V at idle. I wasn't happy since I'm supposed to be seeing 14.5ish. So I think, "OK well I've driven on less voltage and the alt seems to charge a little while moving" so I take it out.

Car runs fantastic. Fuel pressure's all there matching the manifold pressure increase I'm seeing. Get to the end of my road ( about a mile away ) and she dies, never to start again. Had a buddy bring me another battery and I get her home.

OK so I've got a direct connection from the alt to the battery and the correct voltages in all the wires going to the alt. What am I missing here?

Cleaning up the battery to body ground here in a bit.

Edited June 3, 2009 by usafdarkhorse

[DeesZ]

You said right up front that the battery is good.... In my mind, I keep coming back to the battery as being the culprit. I could be way off base, but I'd go back and check the battery to be certain it is good with voltage and amps.

[usafdarkhorse]

You said right up front that the battery is good.... In my mind, I keep coming back to the battery as being the culprit. I could be way off base, but I'd go back and check the battery to be certain it is good with voltage and amps.

Yeah I would question it too, but I've put in several batteries and all give the same symptoms.

[Nigel1943]

UPDATE:

Alright, so I got the car back from the shop. They put in a new ground from the alt to the body. It seemed to run better, so they checked the voltages.

Apparently the alt is putting out 15V, but it's only getting 13V across the battery, so, due to liability reasons, they recommend ME to put in a cable that goes directly from the BAT connection on the alt to the positive side of the battery. A hotwire if you will.

I get home and do it. Big 4 AWG cable from the alt to the battery. Start it up. I get 11.9V across the battery, give it a rev or two, and it settles around 12.5V at idle. I wasn't happy since I'm supposed to be seeing 14.5ish. So I think, "OK well I've driven on less voltage and the alt seems to charge a little while moving" so I take it out.

Car runs fantastic. Fuel pressure's all there matching the manifold pressure increase I'm seeing. Get to the end of my road ( about a mile away ) and she dies, never to start again. Had a buddy bring me another battery and I get her home.

OK so I've got a direct connection from the alt to the battery and the correct voltages in all the wires going to the alt. What am I missing here?

Cleaning up the battery to body ground here in a bit.

So are you saying the battery is dead after 1 mile?

[usafdarkhorse]

Yes. It evidently wasn't charging at all as I was going down the road ( as opposed to very very little at 3000RPM, around 13.0V potential ), so when it decided to die at the stop sign, it didn't have enough juice for the starter.

[Nigel1943]

Yes. It evidently wasn't charging at all as I was going down the road ( as opposed to very very little at 3000RPM, around 13.0V potential ), so when it decided to die at the stop sign, it didn't have enough juice for the starter.

Have you checked the voltage regulator ?

[usafdarkhorse]

Have you checked the voltage regulator ?

Forgot to mention that the externally regulated alt was swapped nearly a year ago to an internally regulated unit via this thread:

http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

These problems all presented themselves when the last alternator gave out.

[Nigel1943]

Forgot to mention that the externally regulated alt was swapped nearly a year ago to an internally regulated unit via this thread:

http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

These problems all presented themselves when the last alternator gave out.

Ok, so all the "new" alternators you've tried are internally regulated (ie ZX type not LT 160 or similar ), yes ?

[usafdarkhorse]

You are correct

[Carl Beck]

Were any of the Batteries you tried - new? If not, were any of them load tested?

Did anyone already say - replace the battery cables/terminals?

FWIW,

Carl B.

[usafdarkhorse]

Nope, not new. Yes they were tested.

The terminals and cables honestly look brand new, but I can try it.

[Carl Beck]

Nope, not new. Yes they were tested.

Exactly how were they "tested"??

A battery can test out fine with Voltage - due to a surface charge in the plates - - but when put under a heavier load they can short out and go DEAD. That is why I ask if the battery had been "Load Tested".

You can put these batteries on a charger and they will take a charge. They will hold a charge over a 24/48 hour period just fine. The only way you find the problem with them is by putting a progressively heavier discharge load on them...

At the very least make sure your battery terminals, and cable terminals are clean and shinny, as well as being tight. Wire brush the terminals down to shinny new metal... You can not trust how they look.

This is a very simple electrical system - so you can bet something simple is out of wack...

FWIW,

Carl B.