I've tried to search this, but to no avail. Perhaps there's a different keyword to use, but I don't know what it would be....anyways here goes.

1984 RX-7 GS, with a 2nd generation used alternator recently installed, however my issue is with the insufficient power being supplied to my car. Every time I turn something on, the available power on my battery meter decreases noticeably. It's winter and snowing pretty hard, but if I can't seem to have my lights on, my heat, my rear defroster, and sound system on at the same time without running into power issues. Is this a common problem? Is my alternator still insufficient? I want to install a sound system but I can't imagine my car being able to supply the additional power. What's wrong? My battery meter even dances when I put the blinker on. Don't get me wrong the car is drivable, but I want to use it to it's fullest extent.

 

this all sounds pretty normal, i have the stock alternator, i was (no longer have it) running a 1k watt amplifier with a 12" sub, and during winter nights (lights, heat on) i would turn my turn signal and the voltmeter would fluctuate between 12.5- 13V...w/ all that stuff off it would run steadily at 13V. so i'm guessing with the 2nd gen alt. you're better off and i wouldn't worry about it unless it gets bellow 12 V

 

Damn, I knew I forgot to throw that in there.

Yes it falls below 12v. And when it does it causes issues. The car has always been this way. Is it a flat out alternator issue, and perhaps I need a totally new Alternator? Or maybe there's something I can adjust?

 

Check your grounds, and possibly reground everything. This is the cause of most problems.

 

Grounds...okay. Can you Barney-style this for me? Or perhaps point a reference for checking all the grounds? I'm an attempted-car-enthusiastic, but I'm still pretty lacking in common knowledge.

 

arent we all? im interested in this "Barney-style grounds as well"....theres a lot of electricals that still dont work in my car....the electrical mirrors went out after i changed all the fuses -_-

 

Basically follow the negative battery cable. It should be grounded at least twice, Once on the fenderwell in a bundle, and lastly on the trans bellhousing/rear iron. Make sure both are clean and tight. If it still persists, then add another ground. What I usually do is get some 8 or 10 guage wire and ends big enough to fit in the bolt of both the cable end and the coil mount. Make sure you give some extra length to it for some flexibility. That should take car of it. Always works for me

 

It sounds like grounds to me also. I had the same problem years ago. To check it, I used a wire with alligator clips, attached one to the engine and the other to the shock tower bolt. Checked my gauge and it went up considerably and stayed. For the permanent solution, I got a battery cable with double rings, repeated the process except I bolted it to the side of the shock tower.
Hope this helps.

 

Sounds great, I'll give it a look then get back to you fellas. Thanks for the quick responses.

 

Ground point on the fender is very important and often gets loose. Make sure the battery terminals are clean. The stock battery cables can corrode internally. New cables may help. Make sure all the terminals on the fusible link box are clean.

 

There are a number of ground points on the car; only way to find and check them all is withthe wiring diagram. But for widespread issues like this, the one on the engine and on the fenderwell are the most important.

Also make sure the output conection on the alternator is clean and tight, and battery terminals are as well.

Got to make sure the electrons can get into the battery/systems... and they come from the ground side!

(Yes, alternators are actually electrical vacuum pumps... who knew?)

 

Excellent post by FirebirdSlayer666 ... this lead me to find a problem that I was having with a rough start (slow turn-over) and I found that the primary terminal for the ground coming off of the battery was poorly connected (to the engine). I was getting just enough ground from the strut tower that would allow me to crank it but this post was a great help (for specifically spelling it out = I needed the Barney-style reference too). Thanks again.

 

It also doesn't hurt to go through all of the electrical connectors and clean them up. 20 odd years of atmosphere and moisture leads to a decent amount of corrosion even on interior connectors. You'd be surprised how much unnecessary resistance that it puts in the circuit. electronics cleaner and some dielectric grease will do the trick on it though.