3 wire to 1 wire Alternator

[bouska]

I have a 2000 2300v with a mercruiser 350 Black Scorpion and am upgrading from a 70 amp 3 wire alternator to a 115 amp 1 wire. Wanted to make sure I have everything figured correctly. The original alt had 4 wires running to it orange(main + from alt), Black(ground), Purple(from ignition switch) and red/purple(runs to circuit breaker and instrument panel). To go to a 1 wire should I remove the purple and the red/purple and not use them? I am also going to replace the orange with a larger wire. It goes to a 90 amp fuse. The battery runs to the starter. Off of that post is the fuse the other side of the fuse has the orange from alt and a red that runs to the circuit breaker. Am I correct in thinking that this is fusing the alt from the battery. I don't like the idea of a fuse on an alternator. If the 90 amp fuse is necessary will the 115 amp alt blow it and then damage the alternator. If that is the case could I remove the old wire and just run the new wire to the battery? I am familiar with 12v systems but in no way an expert so any input would be greatly appreciated.

[spharis]

The fuse is for the starter draw and isn't necessarily required. If you plan on running a wire from the alt to the battery bank/area, then you will not fuse it. If you are going to go to the starter (same as factory location), then you might need to upgrade that fuse, but you probably will not need to. I doubt your alt will ever be taxed over 90amps. If it blows, then upgrade it.

All the other wires can be left off. The signal to the dash is likely a tach signal, an excite wire, or to a trouble light. It is NOT required for proper alt operation. I doubt your tach is getting signal from the alt, so it is probably going to a trouble light or for the original exciter. You will also not need the ground. The alt case grounds directly to the engine block. The idea is to remove everything but the one wire and it really cleans everything up.

[bouska]

Thanks thats what I thought just wanted to hear it from someone else. I am used to dealing with 1960's cars and trucks. Very simple electrical systems. I was wanting to just run straight to the battery but when I noticed the fuse I wanted to make sure there wasn't something I was missing something. Not used to so much electronics and computers. The alt requires a ground of same gauge running straight to the battery for warranty so will do that as well and just remove all the old wires. Once again thanks for your help.

[spharis]

No problem. If you have the wire, I would just run both of them back to the battery. I think the only issue you would run into might be if the tach pick up is on the alt, or if you have a trouble light. Post some pics!!!


Also just curious....what brand is actually requiring you run the ground to the battery. I guess they think the 00 running to the block and the alt bolted to the block isn't enough grounding???

[bouska]

Wire is not an issue. The wires I tracked match my wire diagram. There is no tach or trouble light on the alternator. Looks like just for the exciter. Looked at the warrenty again and it says not covered if failure due to no ground or poor ground but a tag on the alt says to run ground straight to battery with same gauge as positive wire. Positive says min. 4 gauge. So not sure if they would cover it or not. It is an AmFor Electronics alt they are part of Wrangler NW Powerproducts in oregon. They mainly do very high output alts for offroad trucks. I had heard good things about them and when I called DB after reading on here they recomended them as well. I like to keep my money local if possible which would have been DB but thats ok. Don't have any pics the alt is sitting in the floor of the boat at my slip. I will try and take some in the next few days.