Bouncing Battery Gauge

[Kurt B.]

Gentlemen,
1968 Corvette smallblock, factory original car
Completely restored 2 years ago and recently developed a bouncing needle in the battery gauge when electrical accessories are turned on.
Symptom occurs at idle and also while driving at speed.
Car runs flawlessly, gauge worked perfectly up until a few months ago but now bounces violently near the zero (center ) position on the gauge.
Alternator and voltage regulator were rebuilt by John Pirkle so they are not suspect. Everything electrical works perfect.
Car is not driven much but exercised regularly on perfect sunny days.
Last night, while sitting at intersection with turn signal on, needle bounced to the left (discharge) each time the turn signal flashed.
Battery is 2 years old and always maintained on Battery Tender when car is not driven.

What should I be looking for and please consider that I know nothing about automotive electrical?
Thank you,

Kurt Bunting
#26406

[Jack H.]

Re: Bouncing Battery Gauge

Let's see '68 was the last year for electro-mechanical, external, '515 voltage regulator. The symptom you mention (sitting at light, idling, and seeing ammeter twitch in lock-step to turn signal flashes) suggests the charging system isn't delivering sufficient output for the current drain and/or isn't reacting fast enough to system load dynamics.

I don't care who rebuilt this/that or when...we're talking about aged classic car parts and there's no limit on when something's going to decide to go 'south' on you.

Since you tell us you're NOT an electrical, guhru, good! Check around your neck of the woods for a competent auto electric shop. They should have a roll-out diagnostic cart they can put on the car and exercise the key electrical components (battery, voltage regulator, alternator) for you in roughly 20-minutes flat. That'll tell you without 'guessing' waz up and save you from replacing by substitution this/that item...

A good shop shouldn't charge more than $40 for the diagnostics and IF it's something simple (e.g. a flakey connector wire at the regulator or alternator) put it right for you in virtually no time!

[Kurt B.]

Re: Bouncing Battery Gauge

Thank you Jack
I guess I need to find an auto electric shop
Kurt

[Jack H.]

Re: Bouncing Battery Gauge

Kurt, if you don't know of a reputable local auto electric shop, here's a 'trick' I learned many years ago--ask a cop.

Cop? Why would local police know about auto electric shops?

Well, most police cars are LOADED with special/unique electrical items (roof flasher lamps, siren, radios, Etc.) and the conversion chores are typically let out for public bid. Those shops who are the sucessful low bidders for supplying contract auto electrical labor to the local cop shops are generally:

(1) VERY skilled

and

(2) honest almost to a fault

[Joe R.]

Re: Bouncing Battery Gauge

Kurt,

What you really need is a new amp gauge. Like Jack says the car is getting old and there is a viscious fluid in the amp gauge that dampens the oscillations you now see on your gauge.

After 41 years the fluid has run out and left the meter without damping.

Fork out the $75.00 for a new one and your problem will be solved.

JR