Battery gauge capacitor for 62 vette

[John O.]

Hi all

Last week I bought and installed the capacitors for the coil, regulator, and generator. They were out of stock on the one that goes on the battery gauge. I found in a box of my parts what I believe to be that capacitor. This one is white in color, about 2 inches long, approx. 3/8 " diameter with a lead on each end. I can't see no writing on it, worn off.Does this sound like it is a capacitor? How do you test it to see if it is good? My 62 corvette is the 149th car built.Did the capacitors change from 61 to 62?

Thanks............John

[Mike E.]

Re: Battery gauge capacitor for 62 vette

58-62 were all the same. These are generally a dark mustard-yellow color rather than white. otherwise, the description sounds about right.

[John O.]

Re: Battery gauge capacitor for 62 vette

Hi Mike

Is there a way to test the capacitor to make sure it's good?

Thanks.........John

[Jack H.]

Re: Battery gauge capacitor for 62 vette

Yes, you mount it on a 'Digi-Bridge' LCR meter and test it for two performance aspects: (1) storage capacity, and (2) leakage profile. Think of the capacitor as a bucket for storing water. It's no good to verify the bucket, indeed, has its rated 1 gal, 2 gal, Etc. storage capacity but the bottom/sides of the bucket are riddled with holes. So, it takes two to 'Tango' in verifying the performance silhouette of a capacitor.

Not many have the test tools to verify the integrity of electrical energy storage devices (inductors, capacitors), but just about everyone has a multi-meter capable of verify passive resistance. A good LCR meter of laboratory grade will typically run $1000 and up.

If you're serious about testing your capacitor(s), then go look for a nearby practicing electrical engineer who can take them in to work and profile them for you using his company's lab test equipment.

[Dennis A.]

Re: Battery gauge capacitor for 62 vette

John...

Look for the black band (to ground) this may be a tip-off for the #7270568 capacitor.

[Jack H.]

Re: Battery gauge capacitor for 62 vette

Dennis, the 'black band' on a factory original 7270568 'ammeter' capacitor doesn't indicate 'ground'.... The capacitor is as fully non-polar device and doesn't care which end is positive, which end is negative.

The band was stenciled to indicate which end lead of the cap was physically connected to the outer most internal plate's foil wrap. The mounting orientation of the cap based on the black band was a pedantic and obscure 'safety' consideration of rather dubious value.

The idea was this is an axial lead wax-foil capacitor installed without center body support (eg. no mounting band). It's possible for it to rub against the back of the instrument cluster (electrical ground) due to shock/vibration.

IF it does, then it could wear through the wax coating. IF that happened, it could further wear through the cardboard body. IF that happened which side of the capacitor would we like to short to the instrument panel FIRST, the 'hot' side of the cap internally or the cold side of the cap?

So, the convention became to designate the lead wire connected to the outer most foil plate and install the cap to make that be the cold side. Now, if IF, IF and IF happened, the cap would simply stop working instead of shorting out the battery...

Well, if IF, IF, and IF really did happen, the owner/operator would have no warning of the cap having failed and it would eventually wear through the inter-plate insulation and reach the HOT side of the cap! Yes, this was a HUGE safety precaution on Delco's part, well worth the time and effort (that's obviously stated tongue in cheek)!

[Dennis A.]

Re: Battery gauge capacitor for 62 vette

Jack...

I just thought that the black band may identify the capacitor. Adding to your response, I understand that the mounting of this capacitor is more for "correctness" than function, in fact leaving it not connected may be the best thing.

[John O.]

Re: Battery gauge capacitor for 62 vette

Hi Jack

If I just decided to install this capacitor,whats the worse that can happen.If it had low or no storage, I would just get more interferance in the radio, correct?

Thanks..John

[Jack H.]

Re: Battery gauge capacitor for 62 vette

If storage capacity was off-spec, you'd observe more RFI than designer's intended. Remember the 'ammeter' cap was a pretty essoteric ('cosmetic') device intended to thwart the turn on/off switching transients associated with changing headlights. So, you have to be driving at night + in an AM fringe reception area to notice much. Probablity with a 'weekend warrior' car -- virtually ZERO!

Now, if the cap was of correct capacity but it was leaking like a SIEVE, your worst case scenario is dead short the battery to ground trhough the cap and SMOKE your wiring harness...