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main pwr feed into dash protection/fusing question


3046moparcoupe

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I'm wrapping up my wiring harness build and have one more correct decision to make regarding the power feed  coming into the dash. 
 
I want to protect that 10 gauge wire coming straight from hot battery into the input side of the amp gauge, which then in turn goes on to power other parts of the dash electronics..
 
I'd rather use a fuse than a circuit breaker.
 
My generator is rated for 35 amps max. The fuse panel I have is only rated for 30 amps max PER CKT.
 
 I've removed the amperage from my headlights coming into the dash (with an external relay), so there's 15 amps less than original design right there, I'm not going back with a radio of any kind, I also have a couple of other fused power feeds coming into the dash area for the 6vdc / 12vdc converter, so I also could use these feeds to power my heater blower motors, etc....so I will have much less amperage running through this wire than per the original design.
 
So I've reduced my in dash amperage down to what should be well under the 30 amp rating max PER FUSE, of the fuse panel I'd like to use.
 
But here's where I'm unsure on this,....let's say for some reason: battery condition, overall usage at a single given time, etc,....and the voltage regulator tells the generator to charge at its maximum of 35 amps....that 35 amps will be present on the hot side of the starter solenoid going back towards the battery,.....so it seems like it would also be sending 35 amps of power in towards the dash towards the amp meter on this 10 awg wire, which would cause my 30 amp fuse to blow.
 
But when you hook up your main 6v cranking battery to that same hot side of the starter solenoid, again same wires...( which will probably be in the hundreds of amps - if cold cranking amps is anything the same as regular amps ? )  all of those cold cranking amps from the battery don't flood into the dash, obviously if they did, your 30 amp fuse on the headlight switch would blow, and your amp meter would just be pegged all the time.
 
So is the purpose of the amp meter gauge : to tell you  how many amps your generator is putting out ? , or to tell you how many amps your pulling/using into the dash area ?
 
Does the max potential of 35 amps, just go as far as the amp meter itself ??  and if so, then the 30 amp fuse on that wire would NOT  BE large enough...
 
So before I commit , cut wires , and start adding stakon connectors,....I was hoping to confirm on this,.
 

Again, I would like to fuse this wire from the solenoid with a 30 amp fuse,...but if that's gonna be too small, I'll go with a 40 amp ckt breaker...

 

thanks for the help here on the forum, I'm pretty regular at needing help and asking questions,...and everyone here on the forum has been super good to send help my way.

 

Steve

Edited by 3046moparcoupe
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A 30A maxi Fuse between the solenoid and the Amp gauge will be fine.  The current in a circuit is determined by the load on the circuit not by the maximum current available.  If you have the headlights on a relay and your biggest current draw is the blower motors then you should not exceed 30A through the Ammeter.

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The only other big amp draw may be cigar lighter (as they were called in the parts books for years).

The amps needed determine current flow to the amp gauge matches requirements as available from the generator/battery as described by rhelm1953 above.

Taking the headlight heavy draw with relays eliminated one of the biggest amp draws in the car..

Even if the battery is low causing a 35 amp charge to it - the usage through the wire to the amp gauge is still as Needed for car operation. Amp gauge will read high to the + side which just says to you that you are charging the battery at a higher amp rate than you are using. Most of the amp charge is going to the battery and Not to the amp gauge for operation.

 

Hope that make some sense!

 

I think you are good to get onto the road ASAP!!  ?

 

DJ

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