To Those Who Dabble In The Dark Arts Of Auto Electric (Alternator Problems?)

[mike23109]

I recently upgraded from a 140 amp alternator to a 220 amp unit. I've got twin electric fans, electric fuel pump, AC, etc. With the old alternator I was putting out just under 13 volts (per the AutoMeter gauge). This would dip to around or under 12 volts with the AC running and the headlights on. When I upgraded to the new alternator (one wire unit) I also went with a 0 gauge wire to the battery. When I fired it up it read just over 13 volts on the gauge. When a checked the input wire at the battery it read 14.4 volts. Am I missing something here? Where did the juice go? Any help from those who are in the know would be appreciated. Mike

[67 455 Bird ragtop]

Just curious what make/year of car you are running. Here is a link to a story/site that mey help you out. While not for you specific problem it may help solve/explain it. This site has a ton of good electrical info on it. So take a little time to look around and read a few items. Hope it helps.

http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

[mike23109]

Thanks. I've used him in the past. I think I'll give him a call. As I remember, he is tough to contact.

[H2Ogbodies]

Without knowing what kind of car, I would assume you are seeing a little over a volt of loss due to both the length as well as the number of junctions that your 12V gauge lead ties into somewhere inside your wire loom. You will have a common lead (normally tying in the starter hot, fuse panel hot, AC blower high speed relay lead and battery charge lead all soldered together. At the fuse panel there is a two or three terminal buss bar that distributes 12V power back back underhood for things like headlights, etc. but not before running that power through switches of course. So given that and the shear length of the wiring and its size, it's understandable how you are seeing over 1 volt of loss. For this reason, relays are desired to provide optimum power to all devices. And for the record, all 12VDC electrical accessories are designed to run most effectively @ 14V anyway so using relays is the best route to go for pretty much everything. For high powered accessories, there is a big difference in the quality of the relay internals as far as the latching and release contacts. If you need any help with any of this, let me know-I can offer some options!

[mike23109]

Thanks for the info. I probably should have provided this info initially: I have a 1970 chevelle. I've upgraded the fuse box with a new Painless Wiring unit. I have relays for both my headlights and electric fans. I probably need them for the AC too. I think I've got this figured out now. Thanks for the offer of help. If I find myself in over my head I'll definately contact you.

[MonzaRacer]

Run the gauge as directly to the battery as possible rather than through wiring harness, use a fused or fuse link wire and ground as close to it as well.
To many feet of wire and too many connections will cause issues.
Another issue is to many companies only do machine crimps, I have worked on many of the newer systems and had to go through and solder the crimps to fix minor electrical gremlins.
I watched one company that used to tin and solder connections and and heat them as they crimped the terminal, this made a very good connection and as long as properly supported and done it makes better connections.
I read that some of the people at Painless people dont believe in soldering crimped connections but I have found I have better luck doing it.
I have several customers who I wired race cars and if I crimped them only I always had to go back and fix issues. So now I crimp and sold the connections, I put a tool kit in the cars right next to the driver, they get all the parts they need to do quick fixes at the line then I resolder them later on.

[H2Ogbodies]

Yep-me too...I solder all of my connections on harnesses as well.