FC alternator concern.

Rotary#10 · 08-01-2010, 11:14 AM

Hey Folks, I have a 90 n/a fc rx7 and my concern is at times I have noticed the volts gauge reading @ 14 volts and sometimes alittle over 14 volts. It that alright? What do you think?
I think its not, so what I do is turn on my headlights, interior fan, radio etc and thus brings the volts back to 12.5 volts or so. Are there any long term negative effects if I don't take this measure of turning on the accessories and bring the volts down ? This mostly happens in the morning or after the car has been sitting a day or 2 without driving.
Thanks.

infernosg · 08-01-2010, 11:22 AM

I'm pretty sure a healthy charging system outputs 14-14.5V. An output of 12V would mean your either heavily loading the system or running straight off the battery. Either way it sounds like your charging system is in good shape so I wouldn't complain

RETed · 08-01-2010, 02:47 PM

That's normal for a stock FC alternator.
If you haven't figured it out by now, the stock FC alternator SUCKS.

-Ted

My5ABaby · 08-02-2010, 09:19 AM

14v is fine. I'd check it at the alternator/battery to see what it really is though since the gauge may be off. My gauge always reads 12 or under yet I haven't had an issue in 10,000 miles.

Rotary#10 · 08-02-2010, 01:36 PM

Okay good. I thought something was broken. oh LOL old cars.

MmSadda · 08-11-2010, 09:08 AM

14 is spot-on. Granted, I run a pair of 12" subs in the back of my car, but mine sits around 12.5 to 13. Sometimes down to 11.5 with the bass up high

I'd kill for an alternator that didn't fall below 12.5.

vex · 08-11-2010, 11:57 AM

You and me both. I'm looking in to it as I don't want to have to deal with my charging system as it currently sits and may infact tax it with some of the modifications I have planned. I need to locate a parts distributor for the FD alternators so I can rebuild the one I have.

Akagis_White_Comet · 09-16-2010, 09:08 AM

I have a FD alt sitting in my garage. Used it for about 2 years and it always did a fantastic job on my stock 87 GXL, putting out a solid 14 volts at idle when pulled from my car.

Gotta say that I was impressed with it. The car had a s4 alt on its last legs and simply was hell on the battery. The FD alt cured it and was my first mod. But after swapping to a Taurus 2-speed E-fan, the FD alt was getting pushed a bit more than I felt comfortable with. One day of it was all that it took to convince me to pull it to prevent damage and grab the alt from the same Taurus that the fan came from.

It's an original Mazda one too, no autozone 'rebuilt' crap. If you're interested, pm me and I'll give you a great deal on it.

classicauto · 09-16-2010, 01:44 PM

Rich, goodfella, has some beefy ass re-wound FD alts available as well.

I've never over worked the FD alt I have, a fresh bosch unit from carquest, but I don't run much in the way of amp heavy items other then my dual e-fan.

Buggy · 09-16-2010, 02:17 PM

I'm running a 10" sub, amp, taurus sho e-fan, gauges, and other goodies on my FD alt, works fantastic. Seeing 14V at startup isn't anything unusual especially if that car has been sitting for a few days. The system is sensing that the battery is slightly low on charge and is full fielding the alternator so it brings the battery back up to life. You may even notice it charge high like that on colder days as well.

08-01-2010, 11:22 AM	#2
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA iTrader: (5) Posts: 811 Rep Power: 15	I'm pretty sure a healthy charging system outputs 14-14.5V. An output of 12V would mean your either heavily loading the system or running straight off the battery. Either way it sounds like your charging system is in good shape so I wouldn't complain __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS

08-02-2010, 09:19 AM	#4
My5ABaby Sigh..... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (6) Posts: 2,377 Rep Power: 19	14v is fine. I'd check it at the alternator/battery to see what it really is though since the gauge may be off. My gauge always reads 12 or under yet I haven't had an issue in 10,000 miles. __________________ 1986 Sport: 132k miles, 5A (Sapphire Blue Metallic), Tokico Blues, Racing Beat Springs, Custom LED tailights (only S4 LED tails in the world), SSR Mark II, Racing Beat exhaust, S5 black interior, Rotary Resurrection rebuild at 120k miles Community Service Manual RotorWiki "Imagination costs nothing; we could build square locomotives or fly to Mars" - Felix Wankel Yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."

08-02-2010, 01:36 PM	#5
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	Okay good. I thought something was broken. oh LOL old cars. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

08-11-2010, 11:57 AM	#7
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. iTrader: (6) Posts: 2,113 Rep Power: 19	You and me both. I'm looking in to it as I don't want to have to deal with my charging system as it currently sits and may infact tax it with some of the modifications I have planned. I need to locate a parts distributor for the FD alternators so I can rebuild the one I have. __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

09-16-2010, 09:08 AM	#8
Akagis_White_Comet Comealong busts your nuts Join Date: Jan 2009 Location: Columbus, OH iTrader: (0) Posts: 29 Rep Power: 0	I have a FD alt sitting in my garage. Used it for about 2 years and it always did a fantastic job on my stock 87 GXL, putting out a solid 14 volts at idle when pulled from my car. Gotta say that I was impressed with it. The car had a s4 alt on its last legs and simply was hell on the battery. The FD alt cured it and was my first mod. But after swapping to a Taurus 2-speed E-fan, the FD alt was getting pushed a bit more than I felt comfortable with. One day of it was all that it took to convince me to pull it to prevent damage and grab the alt from the same Taurus that the fan came from. It's an original Mazda one too, no autozone 'rebuilt' crap. If you're interested, pm me and I'll give you a great deal on it. __________________

08-01-2010, 11:14 AM	#1
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	FC alternator concern. Hey Folks, I have a 90 n/a fc rx7 and my concern is at times I have noticed the volts gauge reading @ 14 volts and sometimes alittle over 14 volts. It that alright? What do you think? I think its not, so what I do is turn on my headlights, interior fan, radio etc and thus brings the volts back to 12.5 volts or so. Are there any long term negative effects if I don't take this measure of turning on the accessories and bring the volts down ? This mostly happens in the morning or after the car has been sitting a day or 2 without driving. Thanks. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

08-11-2010, 09:08 AM	#6
MmSadda BOOSTED COLON Join Date: Feb 2008 iTrader: (0) Posts: 88 Rep Power: 17	14 is spot-on. Granted, I run a pair of 12" subs in the back of my car, but mine sits around 12.5 to 13. Sometimes down to 11.5 with the bass up high I'd kill for an alternator that didn't fall below 12.5.

09-16-2010, 02:17 PM	#10
Buggy I've been Wankeled! Join Date: Apr 2010 Location: Mildmay, Ontario, Canada iTrader: (0) Posts: 260 Rep Power: 15	I'm running a 10" sub, amp, taurus sho e-fan, gauges, and other goodies on my FD alt, works fantastic. Seeing 14V at startup isn't anything unusual especially if that car has been sitting for a few days. The system is sensing that the battery is slightly low on charge and is full fielding the alternator so it brings the battery back up to life. You may even notice it charge high like that on colder days as well. __________________ 1976 Rx-4 hardtop. Half bridge 3B 13B, S5 NA rotors, Renesis e-shaft, stat gears, and bearings, balanced rotating assembly, RE dual weber 36 DCD's 203rwhp 137ft-lbs torque DGRR 2011 3rd place 1974 Rx-4 all original 27,000 miles 1988 Rx-7 TII 320rwhp. DGRR 2012 3rd place