Ammeter pegged to the right

**William C.** · October 10, 2010, 11:38 AM

Re: Ammeter pegged to the right

Either the battery is demanding a high charge rate, or the Regulator is asking for a high chargr rate when not required. What is the voltage reading across the battery terminals with the battery fully charged and disconnected from the car? If around 12.8 the battery should be well charged. Secondly how much does it lose from the charged state if left disconnected over a few days? That should give you an indication of the battery state and you can go from there.

**Chuck S.** · October 10, 2010, 02:08 PM

Re: Ammeter pegged to the right

Back when cars had dc generators and separate regulators, my experience when the ammeter pegged was Bill's second choice : The regulator contacts would weld together from high current flow and continue charging at maximum rate until the battery was cooked.

Back in those days, if you discovered it was a regulator problem before the battery was burned up, you "filed" the regulator contacts and hoped for the best. Or, if you had the cash, you replaced the regulator. I'm sure that filing the diodes won't help, but maybe it's still a regulator failure...the last gasp of a classic alternator attempting to recharge a discharged battery.

A symptom of overcharging the battery, and faulty regulation, will be boiling acid out the fill holes; your battery will probably be history by that time. Bill has a good idea to disconnect the battery and see if it loses charge relatively quickly; i.e. "dead cell".

**Patrick H.** · October 11, 2010, 07:57 PM

Re: Ammeter pegged to the right

Update:

Resting voltage, 48 hours after last drive in the car, everything still connected, was 12.47 volts.

Started the car, and the ammeter went up to halfway between the 0 and +40. As the car warmed up it was very slowly making its way closer to 40 but never went above about "30" (if it existed) in the 30 seconds it ran. After shutting it off, checked voltage which was 12.77, all still connected.

Connected trickle charger and it showed the battery as needing a charge. We'll see what it looks like tomorrow.

I may take the alternator in to get tested tomorrow too.

Patrick

**John H.** · October 11, 2010, 08:00 PM

Re: Ammeter pegged to the right

Patrick -

Did you check the voltage across the battery terminals with the engine running? Should be 13.8-14.2 volts at a high idle (1200-1500 rpm).

**Patrick H.** · October 11, 2010, 08:12 PM

Re: Ammeter pegged to the right

Originally posted by John Hinckley (29964)

Patrick -

Did you check the voltage across the battery terminals with the engine running? Should be 13.8-14.2 volts at a high idle (1200-1500 rpm).

I will tomorrow.

Exhaust disconnected at the engine since the donuts (brand new, came with CC system) burned out after less than 100 miles of use, and the new sintered metallic ones go in tomorrow. There was a limit to how much noise I wanted in the barn.

I assume if voltage is that high then the alternator is OK?
Or ?

Electrical is not my thing....

**John H.** · October 11, 2010, 08:16 PM

Re: Ammeter pegged to the right

Originally posted by Patrick Hulst (16386)

I assume if voltage is that high then the alternator is OK?
Or ?

Electrical is not my thing....

If the voltage is in that range (13.8-14.2 volts), the regulator (internal in your case) is operating properly. If it's over 14.5 volts or as high as 15 or 16 volts, the regulator needs replacing.

**Patrick H.** · October 11, 2010, 08:25 PM

Re: Ammeter pegged to the right

Originally posted by John Hinckley (29964)

If the voltage is in that range (13.8-14.2 volts), the regulator (internal in your case) is operating properly. If it's over 14.5 volts or as high as 15 or 16 volts, the regulator needs replacing.

Thanks.

And if low, the battery?

**John H.** · October 11, 2010, 09:25 PM

Re: Ammeter pegged to the right

Originally posted by Patrick Hulst (16386)

Thanks.

And if low, the battery?

If it's low (engine running), the alternator isn't getting a charge signal from the regulator.

**Jack H.** · October 12, 2010, 09:55 AM

Re: Ammeter pegged to the right

BW to diagnose is NOT to remove parts and test them individually...

Consider taking the car to a competent auto electric shop where they can roll out out their diagnostic cart on wheels and exercise the electrical system in-car. Why do I say this?

Well, when you remove this/that, you can disturb the 'nest'. Not only do the various charging components have to be good, but their electrical interconnect needs to be good as well. When you disconnect/remove this/that part, you're twisting/moving the the electrical connectors associated with the part. That can result in Jeckyl/Hyde changes...

The 2-wire side terminal on the alternator for this era car is well known for contact 'funny' issues as is the engine compartment's main B+ bus (side of horn relay). So, diagnosing the WHOLE system, as-is & in-place can be a decided advantage to troubleshooting accuracy.

Also, the electrical tech can execute a load test on your battery while you're there. Where in the battery's wear out cycle (progressive loss of gross charge storage) are you today? The load test will tell you the actual cold cranking amperage the battery delivers and you can compare that to the battery's CCA rating...

The whole shooting match (roll up the diagnostic cart and run battery, alternator, regulator tests) should take something like 20-minutes flat and be either free or a minor $-charge issue...

**Donald O.** · October 12, 2010, 02:43 PM

Re: Ammeter pegged to the right

Pat when you check you voltages again, try this:

what is the battery with ignition OFF
what is the battery ignition On

Start engine, but keep at idle, and do not go above 1100 rpm
what is the battery
raise the RPMs to 1500-2000 what is the battery
let engine return to low idle
what is the battery

If your DVM cables are long enough, you should be able to position the meter in the cockpit to read the meter.

DonO

**Patrick H.** · October 12, 2010, 09:06 PM

Re: Ammeter pegged to the right

Originally posted by Donald Olson (17357)

Pat when you check you voltages again, try this:

what is the battery with ignition OFF
what is the battery ignition On

Start engine, but keep at idle, and do not go above 1100 rpm
what is the battery
raise the RPMs to 1500-2000 what is the battery
let engine return to low idle
what is the battery

If your DVM cables are long enough, you should be able to position the meter in the cockpit to read the meter.

DonO

Except my DVM cables have little pointy ends on them, not clips.

**Terry M.** · October 13, 2010, 06:51 AM

Re: Ammeter pegged to the right

Originally posted by Patrick Hulst (16386)

Except my DVM cables have little pointy ends on them, not clips.

Go to Radio Shack and buy adapter clips that have a hole in the back for the pointy end to slide into. Voila clips. There sia Radio Shack by you, right? I thought Holland Michigan was a big town. We are 60K people and have two Radio Shacks.

**Donald O.** · October 13, 2010, 06:59 AM

Re: Ammeter pegged to the right

Originally posted by Patrick Hulst (16386)

Except my DVM cables have little pointy ends on them, not clips.

Isn't your son a NCRS member? Surely he would help you to work on what is to become his Corvette.....

**Patrick H.** · October 13, 2010, 07:41 AM

Re: Ammeter pegged to the right

Originally posted by Donald Olson (17357)

Isn't your son a NCRS member? Surely he would help you to work on what is to become his Corvette.....

I don't own this one.

And yes, 50001 has helped me on this car a bit, though most of the work is just 16386 by himself.

Ammeter pegged to the right

Ammeter pegged to the right

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