Club Cobra - Amp Gauge Blow Up

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- - Amp Gauge Blow Up (http://www.clubcobra.com/forums/era-speak-bob-putnam/132090-amp-gauge-blow-up.html)

If Bliss is continuing to monitor - I'm still curious if the connections at the amp gage were good and tight when he disconnected them?

Quote:

Originally Posted by RICK LAKE (Post 1334184)

GUYS Here's the problem with a curcuit breaker, It protects the wiring curcuit from over load. Downside. IF you have a wiring problem like the amp gauge problem here and the power wire shorts to ground, it will blow and open the curcuit. HERE'S the problem the curcuit breaker cools off and resets. These thing will reset from 10 - 50 times. Each time the problem is grounded and burns the wire coating. Over time you get a melted wiring harness.
Slow blow glass fuses worked for alot of years in a car or truck. They are now plastic and cheaper to make but still do the same thing. If you want to save your wiring harness from burning up, install a maxi fuse and holder. It's not orginial but will protect the wiring harness of the car. You have them on most new cars and truck. They range from 80 amps to 250 amps. It only blows once. Have to find the problem but alot less damage to wiring harness. I have a 100amp for my wiring system and a fusible link of 125 amps on my ALT.
Side note all fuses are measured for ampage ratings of constant load. The problem is when a curcuit is turned on, like lights the amp spike instead of 10-15 amps is 30-40 amps for a split second. This is the reason for slow blow fuses.
Late note IMO wouldn't recommend running parallel curcuits. If you run 2 wires to and from the same terminals and one shorts out. Unless you cut it out of the curcuit it's only going to burn up the other curcuit too. ERA wiring harness is just fine. Issue again is the insolators of the amp gauge from SW or Smith. Theses gauage where not designed to handle 60 amps constant and spikes of over 100 amps on startup if your system is wired that way.
If you want to run the oem look of an amp gauge, leave it unhooked and run a voltage either under the hood or in the glove box to keep a check on the battery and charging system Rick L.

Rick L...who makes 100 amp maxi fuse holders?

Quote:

Originally Posted by RICK LAKE (Post 1334184)

GUYS Late note IMO wouldn't recommend running parallel curcuits. If you run 2 wires to and from the same terminals and one shorts out. Unless you cut it out of the curcuit it's only going to burn up the other curcuit too.

That would only be true if there was a catastrophic fault to ground on the dash ammeter line, not with a continuing increase in resistance on the gauge condition. And a possible catastrophic fault to ground occurrence exists on any configuration, ammeter or volt meter or no gauge at all. But I do agree with you on the 50 amp circuit breaker. There should never be a time that circuit breaker clicks off, ever, for any reason. If it does click off, chances are the problem is not going to clear itself during the short "reset" period. So, all things considered, a one-time slow-blow 75 amp fuse is probably better and just carry a spare in case the short was caused by something innocent, like bumping a wrench from the fuse box to the firewall, or the like. The more I think about it, the more I like the idea of replacing that circuit breaker with a fuse.

Blue Sea makes excellent Fuse Products and I used them exclusively to wire my Contemporary Cobra and will be using their products on my Hi-Tech Cobra:

https://www.bluesea.com/products/category/Fuse_Blocks

They have an AMI fuse box that goes from 30A to 200A and Maxi Fuse holders up to 80A.

I don't think you would be disappointed with any of their products - very high quality.

... or just change out the auto-reset circuit breaker for a manual-reset circuit breaker. I should of thought of that in the first place. Even ol' Rick might agree with me on that.:D Maybe not, though... he's a toughie.:LOL:

Brilliant!!! That is exactly what I am going to do this time. Makes perfect sense. Now I don't have to worry about the auto-reset breaker cycling or carrying a spare Maxi-Fuse.

Quote:

Originally Posted by Mongoose930 (Post 1334208)

Blue Sea also makes ANL fuse holders, which also work with fast blow ANN fuses
https://www.bluesea.com/products/550...r_-_35_to_750A
Since I'm mounting this in the engine bay, a breaker isn't suitable for the heat and vibration. These also look appropriate for a Cobra and accept up to 2/0 wire.

Quote:

Originally Posted by vatdevil (Post 1334223)

Since I'm mounting this in the engine bay, a breaker isn't suitable for the heat and vibration. These also look appropriate for a Cobra and accept up to 2/0 wire.

Cooper has an amp-temp chart for their automotive circuit breakers, you just adjust the rating for the under-hood temperatures. Vibration is the same as anywhere else on the car. ERAs have had their circuit breakers mounted on the engine side of the firewall for almost 30 years now without any problems, but I do think a manual-reset is better than an auto-reset.