Is my battery dying?

[tblackgt350]

I'm running an original 289 that has been converted to pertronix electronic ignition. Two days ago I noticed a surging problem, most noticeable from about 4000 rpm on up. When I slowed back down, I noticed the headlights doing a slight dim-bright-dim routine, and the instrument cluster got dim. Is this most likely the battery giving up?

Thanks for your time and advice.

Tim

[Bob Parmenter]

Good batteries are replaced far too often by guess work. Do yourself a favor, find a reliable automotive tech who has, and knows how to properly work, a battery load tester to determine your battery condition. Then have him check the alternator, and if he knows his stuff he'll have already checked belt condition/tension.

Given your "dim-bright-dim" comment, you or he should check all the electrical system connections (including ground circuits) first.

[Chaplin]

That is usually the sign of a bad alternator. Assuming your charging system is operating properly, once the car is started, the battery is out of the picture and the juice to run the car is provided by the alternator. When the alternator quits and stops working, the car is then forced to draw its power from the battery, which it can do until the battery starts to die. When the alt. is no longer charging, and the battery has been drawn down, all the lights start to dim and eventually all electrical power is gone.

Oh wait a minute, you said dim-bright-dim, not dim-dim-dim. Start with the grounds and make sure all electrical connections are clean and tight, then check the alt. and battery.

Good luck

[Spraygun]

have the battery checked with a hydrometer,a load tester won't always detect a bad cell

[Ron61]

Tim,

The above posts have pretty well covered what the most likely things could be and grounds are really suspect in a lot of electrical problems. If you have a voltmeter and can get the car to do its thing standing still, just measure across the - & + terminals of the battery and see if the voltage varies. Mine runs around 14 volts as the RPMs go above idle and around 12-12 1/2 at idle. I have a dash mounted voltmeter that I watch all the time along with the rest of the gauges. By surging I figure you mean the actual running of the car and at higher RPM you will use more power to fire the plugs.

Ron61
Ron Widener

[Excaliber]

Couldn't be the fan belt slipping?,,,,,nahhh....couldn't be that.

Ernie

[dscott]

It may be a bad regulator. They cause the dim, bright, dim routine when going bad. They are pretty easy to bypass and check the alternator output. A battery generally will not cause that type of problem. Grounds sure will though.
Don