Altenator wiring

I have a 1972 mercruiser 165 I recently replaced my 37yr old gauges with new ones. In the process I replaced my ammeter with a voltmeter. while doing this I changed my wriring slightly from factory. I now have battery power to my key and then from there the guages and accessories (bilge,blower, wipers etc) run of the ignition terminal of the key switch. From this same terminal a lead goes to my volt meter were it connects with the altenator lead from the factory harness. I am wondering if something I did could have killed my altenator as it died right after I made the change. after taking it apart it apears my diode trio is burned up. (it is a delco remy with internal voltage regulator) Thoughts any one? I dont want to burn up the replacement. Thanks

Re: Altenator wiring

The voltmeter does not need an alternator connection. It simply needs a connection to the +12 volt connection on any other gauge, to the "A" (accessory) terminal on the ignition switch, or to the +12 volt buss on the fuse/breaker panel. It is measuring "system" voltage. If you used the old ammeter wiring you very likely did cause the failure.

Re: Altenator wiring

Thank you for the help. Should I now run the altenator straight to the battery? Thanks

Re: Altenator wiring

No! You connect it to the same terminal the POSITIVE battery cable is connected to on the starter solenoid. I suppose you can say that's direct to the battery but this eliminates an extra run of wire and is the way it was wired to begin with.

Re: Altenator wiring

im wondering why you ran the blower throught the ign. now you have to have the key on to run the fan to clear out the fumes. Then your are sitting there for 5 mins running the ign. with no load and thats not good for it.

Re: Altenator wiring

Thank you for all the help. Ok here is what I have done over the weekend. since I no longer have a ammeter wired in series. I installed a posotive post at the console where my battery lead, accessories,altenator and jumper to the ignition all connect. now to my understanding it is back to factoy as close as I can get. The accessories are no longer on the ignition. I have 14.4v at the altenator. 13.2v at the battery. I measure 13.8 on the pos. post at the console. I put my multimeter from the pos on the batt to the pos on the altenator and got 1.2 so I am having 1.2v of resistance or voltage drop somewhere in my pos. side. which runs from the altenator to the 40amp circuit breaker to the console where it connects to my pos. post with the battery and then back to the starter. how do I isolate my resistance or should I not even worry about it??????? Thanks

Re: Altenator wiring

Great job of isolating the voltage drop.

It is likely an old/dirty/corroded connection. Start by pulling the connections apart, sand till shiny and re-assemble.

You should find the problem because this resistance wastes electricity, produces heat and will overtime become more resistant, until you are not charging your battery or able to start your motor.

a little voltage drop from the back of the boat to the front is normal, but that is due to drop in volts over the wire. you should not see any voltage drop throughout the engine compartment.

Re: Altenator wiring

You have an extremely long run of wire/cable from the engine (alternator) to the console, to the battery and then back to the engine (starter). You have an unnecessarily complex wiring scheme and it does not even resemble a factory wiring system. The alternator output on nearly every engine feeds a large terminal on the starter solenoid which has the positive battery cable connected to it. A pair of 10 gauge wires (the boat harness) feeds the console and any accessories up there. You are very likely using too small a wire in this sytem. It would also help a bunch if you posted a diagram of what your current wiring looks like.