the OE 78 amper is one of three alts listed for an '85 Diplomat

Find an old 100 amp Leece-Nevill from a mid 70's police car,have someone go through it and it will bolt on and meet all your requirement and then some.They are not common anymore but still out there or you could buy a new one for just under $200 if you want to spend the money.

Something to think about. What the other people said is true about the car just using what current it needs, BUT, if you have problems anywhere in the wiring like corroded connections and so forth that big alt is just going to feed what ever the bad spots need to get what they want, which leads to overheating and a fire possibility. Let me give an example. I have a 75 model motorcycle that the contacts inside of the ignition switch were pitted or corroded or something bad, cause when I gut to a high enough RPM it would draw so much current that the solder joints on the back side of the switch would melt and the wire would fall off. Just a thought.

I guess the success of the "trick" varies by how you wire in a relay. Pretty simple to wire a relay in so the relay charges the battery and the fusebox only carries the rest of the load.

Personally, I don't use a relay - pretty easy to get the same results without using a $30-40 relay. You simply split the alt output to feed both the battery and fuse block, not the battery through the bulkhead and back out.

And I agree - the problem shouldn't exist - pretty stupid for Mopar to charge the battery through 2 bulkhead connectors and interior wiring.

I sell a lot of the 6 and 8ga wire around cables. How you wire it is important.

I think the poster was talking about the starter relay and termed it battery relay.

What size wire is the red coming from the battery and the black coming from the alternator? How is running power from either side going to impair the system?

I tell people, run the wire around cable, bypass ammeter and leave EVERYTHING else, factory wiring, in place.

Running a 50+ amp alternator with the factory wiring/bulkheads/ammeter is plain not smart. The bulkhead will eventually melt regardless of how clean any terminals may be.

Thanks.

Seem to be a lot of conflicting opinions on this. Maybe I should just leave the old one in, at least till I get around to bypassing the ameter.

If he leaves the factory wiring hooked up and just runs another wire from the alt output to the battery the alt will still feed everything in the car like stock which is through the bulkhead to the ign switch side of the ammeter which feeds everything in the car. But now the battery is not getting charged back through the bulkhead and through ammeter and then the bulkhead again out to the starter relay and fuselink and back to the battery.
He would also render the amp gauge from working right.
Course if he eliminated the stock alt output and only ran a wire to the battery then the output current would go to the battery and then go from the battery back through the stock wiring to the starter relay and then through the fuselink and bulkhead through the ammeter in the wrong direction and feed everything in the car.
Myself I would clean the bulkhead connectors or eliminate the alt and hot feed bulkhead connectors and leave the stock wiring in place and maybe upgrade any wiring that might need it and also run another alt output right to the battery. And then put a voltmeter in the car to moniter the charging system. That way the battery will charge through the one new wire you put in and the alt will also supply the car through the stock alt output wiring which would be through the bulkhead to the hot feed on the ign switch side of the ammeter which feeds everything in the car. Ron

Would you guys say this is the most correct way of doing it? (Diagram on top of page)

http://www.madelectrical.com/electricaltech/amp-gauges2.shtml

NO!!!

Is it the best ?? There are better ways to do it but it will work ok. Looks like they are drilling the bulkhead and running soldered splices which I have done on bulkheads to eliminate them. Dont forget to seal the hole up around the wires if you do it that way. And of course your ammeter wont work so you can do like most and put a voltmeter on an ign 1 controlled wire.
I bypassed my amp gauge and spliced the bulkheads on my 63 and then added a voltmeter. But I was not having any trouble. I figured it was a good idea since the car is over 50 years old. Ron

Yeah I think I'll put a voltmeter in there, it's pretty handy.