Tachometer problem...
04-04-14, 08:27 PM
#27
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So it was rainy and a little cold today and got in the car and the tachometer ran fine and the car felt strong but after about 2 minutes of driving the lights started to dim and the wipers started to get real slow and eventuallty the car didnt want to run at all... I recently upgrade the battery and the Alternator...
Was in the middle of building the sound system which might have just put it over just too much might have to upgrade the alternator more or something but I'm running a tablet which is constantly charging using the lighter socket, a 1200 watt amplifier that I havent even been using yet, its just been sitting there installed with power.
so I had my headlights on, car running, heat on, tablet on, amp on and the car couldnt handle it. drained more than it charged I guess. maybe have to look into an even stronger alternator.
Was in the middle of building the sound system which might have just put it over just too much might have to upgrade the alternator more or something but I'm running a tablet which is constantly charging using the lighter socket, a 1200 watt amplifier that I havent even been using yet, its just been sitting there installed with power.
so I had my headlights on, car running, heat on, tablet on, amp on and the car couldnt handle it. drained more than it charged I guess. maybe have to look into an even stronger alternator.
04-04-14, 08:49 PM
#28
or make sure the current alternator is putting out the rated amps, keep in mind some of these high output alternators put out less than a factory alternator at idle due to rewinding resistance. so you might be working backwards.. there is a point where the amps aren't even worth trying to attain because the alternator has to spin so fast that it burns out and puts out nothing when spun too slow.
IMO, if you need more than 100 amps then you aren't working on a sports car anymore.
IMO, if you need more than 100 amps then you aren't working on a sports car anymore.
Last edited by RotaryEvolution; 04-04-14 at 08:52 PM.
04-04-14, 09:17 PM
#29
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Right now I'm using an S5 alternator and was thinking about going to an FD alternator but you're saying it could be working against me? What do you suggest I do?
04-05-14, 09:51 PM
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disconnected the amplifier and the car seems to do just fine with everything else running except the wipers so maybe I need a better alternator...
04-05-14, 10:32 PM
#32
The first mod I did to my S4 was a FD Alternator and it was fine on a bone-stock car with only a common aftermarket headunit. But with an amp, I wouldn't be so sure.
For the same amount of wiring effort and parts investment as a FD Alternator, why not just skip straight to a 3.8L Taurus Alt instead? 130 Amps is the rated output, but I can vouch for it doing even more on a bone-stock one. When its voltage regulator failed, my first one (an actual Ford part from the junkyard) actually tripped the battery's 150A breaker through 17 feet of 4awg cable. I'm not sure how much power it was putting out then, but I'm pretty sure that the 130A rating is a bit conservative.
04-06-14, 12:41 AM
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Forgot to note that I had to jump the car to get to work today and made it home without any noted changes and went to go get in the car to go to the bar for a drink and the starter spun until it didnt have enough power to even spin any more.... will be buying a car charger because I know the alternator isnt supposed to refill a whole battery then I will have to take a DMM to it.
04-06-14, 05:08 PM
#37
Forgot to note that I had to jump the car to get to work today and made it home without any noted changes and went to go get in the car to go to the bar for a drink and the starter spun until it didnt have enough power to even spin any more.... will be buying a car charger because I know the alternator isnt supposed to refill a whole battery then I will have to take a DMM to it.
The S4's charging system is barely adequate, and the S5's is no better in a stock vehicle. Add some toys, such as an amp or E-fan, and you push the little alternator into being overworked. When this happens, the car starts leaning more heavily on the battery, a device that can only be run into the ground so many times.
From the Second Gen FAQ:
12.6 is battery voltage, 13.5-15.0 when running is healthy. If your engine is running and it's reading under 13.5, the alternator isn't putting out enough power to maintain the battery.
By applying Watt's law and assuming 75% efficiency, we can calculate your amplifier's current draw. Watts = Voltage x Amps
If your amp is rated for 500 watts RMS, it is drawing 41.667 amps (let's round it to 42 for clarity). Divide by 0.75 to account for its efficiency in power delivery and the actual current draw is 56 amps. With an 80A alternator going all-out, that only leaves 24 amps for everything else (so certain things don't work correctly). And should it not be enough juice, it pulls it from the battery, which leads to...
Dead Battery
Dead Battery
Dead Battery
Trashed Battery
For the effort and investment to swap to a FD Alt, it is much more worthwhile to get a Taurus Alt instead. Same pulley, same wiring (different connector though), and though it needs some basic flat adapter brackets made, it's extra heft means it doesn't work as hard to put out its power. Hell, mine did 20A over its rated maximum. Since it did that through 17 feet of cable, the actual output was something even higher
How? Not a reman, not a re-wind and not a chinese copy. Just a plain old Ford part found in a junkyard on a car that's common as dirt. And their fans are good too, so I'm using both.
04-06-14, 05:59 PM
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It is my belief that every FC should have a FD alternator at the very minimum. They are wired the same as a S5 Alternator, but require a dual sheave pulley from Mazdatrix/Atkins Rotary/Racing Beat/etc to use the stock V-belts as the FD has serpentine belts.
The S4's charging system is barely adequate, and the S5's is no better in a stock vehicle. Add some toys, such as an amp or E-fan, and you push the little alternator into being overworked. When this happens, the car starts leaning more heavily on the battery, a device that can only be run into the ground so many times.
From the Second Gen FAQ:
12.6 is battery voltage, 13.5-15.0 when running is healthy. If your engine is running and it's reading under 13.5, the alternator isn't putting out enough power to maintain the battery.
By applying Watt's law and assuming 75% efficiency, we can calculate your amplifier's current draw. Watts = Voltage x Amps
If your amp is rated for 500 watts RMS, it is drawing 41.667 amps (let's round it to 42 for clarity). Divide by 0.75 to account for its efficiency in power delivery and the actual current draw is 56 amps. With an 80A alternator going all-out, that only leaves 24 amps for everything else (so certain things don't work correctly). And should it not be enough juice, it pulls it from the battery, which leads to...
Dead Battery
Dead Battery
Dead Battery
Trashed Battery
For the effort and investment to swap to a FD Alt, it is much more worthwhile to get a Taurus Alt instead. Same pulley, same wiring (different connector though), and though it needs some basic flat adapter brackets made, it's extra heft means it doesn't work as hard to put out its power. Hell, mine did 20A over its rated maximum. Since it did that through 17 feet of cable, the actual output was something even higher
How? Not a reman, not a re-wind and not a chinese copy. Just a plain old Ford part found in a junkyard on a car that's common as dirt. And their fans are good too, so I'm using both.
The S4's charging system is barely adequate, and the S5's is no better in a stock vehicle. Add some toys, such as an amp or E-fan, and you push the little alternator into being overworked. When this happens, the car starts leaning more heavily on the battery, a device that can only be run into the ground so many times.
From the Second Gen FAQ:
12.6 is battery voltage, 13.5-15.0 when running is healthy. If your engine is running and it's reading under 13.5, the alternator isn't putting out enough power to maintain the battery.
By applying Watt's law and assuming 75% efficiency, we can calculate your amplifier's current draw. Watts = Voltage x Amps
If your amp is rated for 500 watts RMS, it is drawing 41.667 amps (let's round it to 42 for clarity). Divide by 0.75 to account for its efficiency in power delivery and the actual current draw is 56 amps. With an 80A alternator going all-out, that only leaves 24 amps for everything else (so certain things don't work correctly). And should it not be enough juice, it pulls it from the battery, which leads to...
Dead Battery
Dead Battery
Dead Battery
Trashed Battery
For the effort and investment to swap to a FD Alt, it is much more worthwhile to get a Taurus Alt instead. Same pulley, same wiring (different connector though), and though it needs some basic flat adapter brackets made, it's extra heft means it doesn't work as hard to put out its power. Hell, mine did 20A over its rated maximum. Since it did that through 17 feet of cable, the actual output was something even higher
How? Not a reman, not a re-wind and not a chinese copy. Just a plain old Ford part found in a junkyard on a car that's common as dirt. And their fans are good too, so I'm using both.
04-07-14, 06:31 PM
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Battery is on a trickle charger while I save the money for an FD Alternator... I just dont have the means to play around with the Taurus Alternator where as the FD one is pretty much a direct swap.
04-07-14, 09:01 PM
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Hmm well I can grab a taurus alternator and makeshift a "for now" bracket and grab the Dual V Pulley for about 140$ whereas an FD alternator would cost like 150$. wiring is mad easy and not really a problem. I think Ill try to go with the taurus alternator for the extra 30 amps for about the same price.
04-08-14, 10:27 PM
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Well recharged the battery and I still have tachometer so I guess the grounds really helped... I still need to upgrade the alternator before I can continue work on the sound system.
04-09-14, 03:17 AM
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Just ordered the Taurus Alternator and the Pulley. Once I get it I can design a bracket for it. Also other note the car got me to and from work just fine today with tach both ways. I guess the amp really was just barely too much for it.
04-12-14, 12:28 AM
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I have the old alternator in it right now and its been getting me to and from anywhere I needed to go. I guess the amp was just pulling too much from it just being on...
04-12-14, 09:22 PM
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I have an e-fan on a switch but idk what its from. doesnt look like too massive of a fan to draw that much power.
update: got into the car and had no tach til about a mile down the road. havent checked plugs yet but thats my next objective.
Got my taurus alt today going to start measurements for the mount bracket tomorrow and still waiting on the double V pulley.
update: got into the car and had no tach til about a mile down the road. havent checked plugs yet but thats my next objective.
Got my taurus alt today going to start measurements for the mount bracket tomorrow and still waiting on the double V pulley.
