Ammeter Question

[superfunk]

Hi,

I'm not familiar with this ammeter in the car, more use to voltmeters. I start the car and it runs well. When I rev the engine, the ammeter follows. It does not go past about 40amps, but its following the revs of the engine. Putting a voltmeter to the battery shows 14-15 volts, again raising with the revs, but not going much over 15. Is this normal, or is it a sign of an electrical problem... volt regulator, bad connections, etc

.. oh yeah, its a '71 and has the original style external regulator.

Thanks,

Adam

[Nissanman]

Sounds unwell!

The ammeter, if all is normal, should be only just on the + or CHARGE side of zero.

To have the needle follow the engine revs is an indication of no regulation in the charge circuitry.

It should NEVER approach 40 amps under normal conditions.

In terms of voltage, the battery should be at or near 12V with engine off, rising to ~13.8V with engine running.

14 -15V is too high, indicating once again lack of regulation.

So, yes, there seems to be a lack of alternator regulation going on:rolleyes:

I wouldn't suggest driving under those conditions, the battery will get very excited/overcharged and may EXPLODE.

Replacement of the regulator is my best guess.

Make sure your battery and alternator connections are in good order when you fit the new regulator.

Actually, now might be a good time to convert to an internally regulated alternator:classic:

[superfunk]

Thanks,

Thats what I had figured, I guess its time to go find a regulator for this baby

[DeesZ]

I have a spare external regulator sitting here that I don't need. Yours for $5.00 + postage if desired. It was brand new from NAPA last year, their $40.00 variety (not the $18.00 cheepo). I had a similar problem with a voltage regulator before it eventually it blew all of the bulbs that were on when the VR gave it's last gasp (literally exploded several of them), and fried the fusible link. Of course it was dark at the time and I had to drag my girl home at midnight. Anyway, consider the upgrade to the higher output 280 internally regulated alternator along with the plug unit that takes care of all the wiring issues. If you decide against the upgrade (which I DO recommend), drop me a PM. The regulator I have has about 5 hours on it and it's getting very dusty on my workbench. Good luck!

p.s. please take the advice to get it fixed before driving any more lest you will be tempting a malfunction that can easily result in a very expensive fire.

As for the plug adapter.... Arne, weren't you involved with making those available at one point? (I could be wrong there, but somehow I think of your yellow Z - which I really like - when I think of those adapter plugs.)

[superfunk]

Im going to stick with the alternator for now. It seems to be working fine, and I cant justify buying a new one at this very moment. Just a couple things I thought I should clear up. It is always on the positive side. Also, my battery froze (oops) and this is hapening after thawing it out and putting a good charge on it. Could the battery be messed and causing that? Either way, im going to get a regulator.. just curious.

[a7dz]

So, if you let the car run does the ammeter return closer to zero? Having the charge up around 40 right after you start the car is pretty much normal as long as it returns to close to zero after a few minutes. What are you running as far as radio and other electronic and electric equipment? All these things play into the equation. Yes, freezing the battery never does them any good. The age of the battery also plays into this equation.

[superfunk]

Its a fairly new battery. The ammeter sits mear zero at idle right after start up. It only goes up when I rev the engine. It will go up to near 40 if I rev it high, and fall back near zero at idle. This is while running minimal electrics. Turning on lights or radio has a minimal effect on the gauge.

Also 14-15 volts at the battery, is that too much?

-Adam

[a7dz]

I have a spare external regulator sitting here that I don't need. Yours for $5.00 + postage if desired. It was brand new from NAPA last year, their $40.00 variety (not the $18.00 cheepo). I had a similar problem with a voltage regulator before it eventually it blew all of the bulbs that were on when the VR gave it's last gasp (literally exploded several of them), and fried the fusible link. Of course it was dark at the time and I had to drag my girl home at midnight. Anyway, consider the upgrade to the higher output 280 internally regulated alternator along with the plug unit that takes care of all the wiring issues. If you decide against the upgrade (which I DO recommend), drop me a PM. The regulator I have has about 5 hours on it and it's getting very dusty on my workbench. Good luck!

p.s. please take the advice to get it fixed before driving any more lest you will be tempting a malfunction that can easily result in a very expensive fire.

As for the plug adapter.... Arne, weren't you involved with making those available at one point? (I could be wrong there, but somehow I think of your yellow Z - which I really like - when I think of those adapter plugs.)

I would take him up on the regulator. It will probably solve your charging problem. Then look into upgrading the system at a later date.

[Arne]

As for the plug adapter.... Arne, weren't you involved with making those available at one point? (I could be wrong there, but somehow I think of your yellow Z - which I really like - when I think of those adapter plugs.)

I came up with the concept for the adapter, and oversaw the initial orders. They were built for me by Dave Irwin (he of headlight relay fame), who still builds them today. I'm no longer directly involved, but you can contact Dave about them in several ways, one of which is a mail link on the alt. adapter info page.

[Zs-ondabrain]

Or I could just say "HEY" and you can follow the Links for the harness's in my signiture. but the ZX plug is best followed thru Arne's link above.

HEY!

Dave.

[superfunk]

Cool, thanks. I'll definately keep that in mind when I do finally go ahead and upgrade my alternator. For now, Im just going to pick up a regulator.

Thanks,

Adam

[V8-240Z]

What happens with the 240Z ammeter when a alternator upgrade is done with a alternator that puts out about twice the amps that the ammeter is rated at? A 45 amp ammeter and a 85 amp alternator. I would think that a ammeter should be matched to the alternator output.