[chevykid90]

now at an idle it will run just above 12 volts, almost 13. if i turn on the heater and my fans it will drop maybe half a volt or so to right at 12. then once it revs up (when i take off) it will go to about 13.5 to 14. (which to me is normal) but now when i turn on my blinker it will drop to about 10.5 at an idle and sit there and rise and fall with my blinker. (like when the light turns off it goes back to 12 then when it comes on it drops down to 10) now my question is were do i go from here?? it never used to do it until about a week ago.

and if it matters i have an 81 firebird with a chevy 454, HEI dis, and dual 14 inch fans. also just running a 65-70 amp alt. thats all the electrical i am running. no stereo or anything.

[bubbahotep]

Doesn't sound uncommon. Once the fans get up
to speed they won't draw as much power. The blinker and bulbs will draw every time they flash. My charge gauge dips with my blinkers too but not down that far (86 Monte, hei, stock alternator) 10v sounds questionable

your battery might be partly drained or dying. It's possible the battery isn't holding 12v or the alternator isn't outputting fully. ? Anything changed recently?

[sqzbox]

If it were me, I'd take it in to AZ or Advance and get the alt tested for free.
While your there, get the battery tested also.

Don't just throw money at what you think might be the problem, find out for sure.

[cobalt327]

Disconnect the negative terminal from the battery and measure the current draw w/the engine off. Except for an accessory that's on w/the key "OFF"- like a clock- there shouldn't be any. If you find there IS, start removing fuses until you find the circuit that is causing the draw.

This will be after you have determined if the charging system is working as it should- including the battery.

[T-bucket23]

Can you check the output voltage at the back of the alternator on the big stud. You could have a connection issue somewhere so the current from the alternator is not making it to the rest of the electrical system.
It doesnt sound like you should be over taxing a 60 amp alternator.

Its not a 1 wire alternator is it

[randolphi]

When Idling a good alternator regulator circuit, is very responsive, It should hold the voltage readings at about 13.10v at idle, and should be capable of reaching at least 13.50 (13.75 also good) with a increase in engine speed.
a fresh battery will demand less from the charging system ,and make a weak alternator seem capable, but more often than not, the alternator fails not long afterward.
The flasher system sometimes, does not draw enough current to cause, the regulator to apply more charge. But if they slow down, something is lacking.

Usually a drop in voltage below 12v. is a good indication something in the system is about to fail, be it charging, or storage system, I would think something has become weakened,
Get them tested, if you like, If you know either, has lots of hours, or maybe 2-3 years, of use already,you can probable bet they are about to fail.

[chevykid90]

the battery is only about 2 months old. i bought it when i finished the motor. but the alternator i have no idea about. was on it when i bought the car back in feb. and when i bought it it had been sitting for about 2 years. i do have 2 new alternators and they are both 75 amp one wire. everything is fine if i dont have anything on, but when i start to turn things on thats when volts drop. and looked closer at it today and it doesn't quit go down to 10 maybe just below 11 volts. now i have another problem that i didnt notice until i was under the hood today and had my buddy start it for me. when he turned the key to start it my fans started spinning but stopped after the engine was started and the key was back in just the "on" position. i know very little about wiring and i could have messed something up, not sure how as i went off of drawings. but hey if its possible i will find a way to mess it up. lol

and i do have a voltage meter and with everything off the battery was at 12.3 volts, going in between 12 and 12.6. but i will try testing the draw and the output from the alternator.

[T-bucket23]

Originally Posted by chevykid90

the battery is only about 2 months old. i bought it when i finished the motor. but the alternator i have no idea about. was on it when i bought the car back in feb. and when i bought it it had been sitting for about 2 years. i do have 2 new alternators and they are both 75 amp one wire. everything is fine if i dont have anything on, but when i start to turn things on thats when volts drop. and looked closer at it today and it doesn't quit go down to 10 maybe just below 11 volts. now i have another problem that i didnt notice until i was under the hood today and had my buddy start it for me. when he turned the key to start it my fans started spinning but stopped after the engine was started and the key was back in just the "on" position. i know very little about wiring and i could have messed something up, not sure how as i went off of drawings. but hey if its possible i will find a way to mess it up. lol

and i do have a voltage meter and with everything off the battery was at 12.3 volts, going in between 12 and 12.6. but i will try testing the draw and the output from the alternator.

One wire alternators do not work well at low RPMs. You would be doing yourself a favor by converting to a 3 wire. They are much better at reacting to system load requirements and will make you battery last longer.

[SSedan64]

X2^^^.
1 wire compared to 3 wire >> http://www.madelectrical.com/electri...hreewire.shtml
http://www.madelectrical.com/electrical-tech.shtml

[vicrod]

Charge the battery overnight or until it's 100% charged. Do the easy stuff first.

vicrod

[chevykid90]

ok so now everything is back to normal today??? and i didnt change anything. but the volts still tick with the lights but it doenst go below 11.5 volts. and idling at 900 RPM it has a little over 14 volts and with everything on it only drops to maybe 13.5.

[T-bucket23]

Originally Posted by chevykid90

ok so now everything is back to normal today??? and i didnt change anything. but the volts still tick with the lights but it doenst go below 11.5 volts. and idling at 900 RPM it has a little over 14 volts and with everything on it only drops to maybe 13.5.

Welcome to the one wire alternator

[chevykid90]

haha ok, so i guess nothing to worry about??

also does anyone seem to know why my fans turn over on start up but not with the key just in the on position?

[SSedan64]

Sounds like you have the Fan wired with start only & not run position.

[chevykid90]

i have then wired directly from the battery to a relay switch that only runs the fans.