Low voltage...still
07-27-2016, 07:55 PM
#1
Low voltage...still What's up guys, I have a 99 f body. My car Keeps going to low voltage a few min after start up. Starts and it's like 13.5ish volts. Then drops down to 12ish. Today it ate a new alternator. It was a Napa high output 220amp. The ls1 alternator simply wouldn't supply the amp draw. Two fans at 25 amps a piece. Twin pumps at 15-17 a piece and a third fan which is similar to 15-25amps(trans cooler fan). I have the tick performance battery relocation kit. I have tried a factory truck 145 amp alternator and same thing. I just put a new pig tail on the alt and still the same thing happening. I have 2 gauge grounds from block to frame. Just wondering if anyone has had this issue. It's causing fuel pressure drop and can't tune the car correctly cause of it.
I looked in DC power alternators but before I buy one cause they are pricy, is there anything I'm missing here? Also the truck alternator I got from the junk yard has 2 wires on the plug that was cut. I told them kg3. But just wanna make sure it's a truck 145 amp and not a 105. Any info would be a huge help
I looked in DC power alternators but before I buy one cause they are pricy, is there anything I'm missing here? Also the truck alternator I got from the junk yard has 2 wires on the plug that was cut. I told them kg3. But just wanna make sure it's a truck 145 amp and not a 105. Any info would be a huge help
07-28-2016, 12:03 PM
#3
I havent tested all of them. But i can tell everything is loising voltage. fuel pressure isnt up. when you first crank the car i have about 55psi and after a little bit it drops to 49-50 and hangs there around 12.3 volts. the ls1 alternator was worse. i was having voltage dip into the low 11s wide open throttle. we immediately stopped tuning. Switched to the napa one, stayed in the lows 12's and just stopped working.
Whats the best way to test for this situation?
Whats the best way to test for this situation?
08-08-2016, 06:21 PM
#4
I have checked and at HOT idle the alternator is producing about 13.6-13.7 volts. now at my fuse box at the front of the car i have 12.8-13.0 volts with both fans running. It seems it is dropping over half of volt of the course of the long wire to the rear of the car. Is this normal? I have about 13.3ish volts at the battery in the trunk and the fuse box is at the end of the circuit coming off of the starter.
I have a tick battery relocation kit. Has anyone else had this issue before? Is this normal?
I have a tick battery relocation kit. Has anyone else had this issue before? Is this normal?
08-09-2016, 10:44 PM
#5
Moderator
You may need to run a bigger wire from the alternator to the fuse box, or build you own fuse and relay box to run your high power pumps and cooling fans.
I had a similar problem on my (custom) car and now run a 4Gauge wire from the alternator to a 150 Amp fuse and then again with 4Gauge to both the battery and main fuse box.
Since your alternator is putting out 13.6 volts, it is working perfectly. The voltage losses are due to too-small wiring.
I'm sure its a pain to rewire a stock car like that, but the wiring "suggestions" for adding huge amplifiers/speakers might give you clues on how to do it.
I had a similar problem on my (custom) car and now run a 4Gauge wire from the alternator to a 150 Amp fuse and then again with 4Gauge to both the battery and main fuse box.
Since your alternator is putting out 13.6 volts, it is working perfectly. The voltage losses are due to too-small wiring.
I'm sure its a pain to rewire a stock car like that, but the wiring "suggestions" for adding huge amplifiers/speakers might give you clues on how to do it.
08-10-2016, 10:30 PM
#6
You may need to run a bigger wire from the alternator to the fuse box, or build you own fuse and relay box to run your high power pumps and cooling fans.
I had a similar problem on my (custom) car and now run a 4Gauge wire from the alternator to a 150 Amp fuse and then again with 4Gauge to both the battery and main fuse box.
Since your alternator is putting out 13.6 volts, it is working perfectly. The voltage losses are due to too-small wiring.
I'm sure its a pain to rewire a stock car like that, but the wiring "suggestions" for adding huge amplifiers/speakers might give you clues on how to do it.
I had a similar problem on my (custom) car and now run a 4Gauge wire from the alternator to a 150 Amp fuse and then again with 4Gauge to both the battery and main fuse box.
Since your alternator is putting out 13.6 volts, it is working perfectly. The voltage losses are due to too-small wiring.
I'm sure its a pain to rewire a stock car like that, but the wiring "suggestions" for adding huge amplifiers/speakers might give you clues on how to do it.
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08-15-2016, 12:00 PM
#10
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Might check that all of the "grounds" are in agreement
and not being jacked apart by return currents and some
excess resistance. Battery, block and chassis sheet
metal all should be within maybe 100mV at full accessory
load. If the block ground (where the alt gets its reference)
and battery are not the same then you can lose voltage
at the battery and at the loads. Anything that returns
current to the sheet metal ground can similarly suffer
when chassis tie points get crusty. Block to firewall straps
seem to get hurt, loose or forgotten a lot. And everything
corrodes eventually.
and not being jacked apart by return currents and some
excess resistance. Battery, block and chassis sheet
metal all should be within maybe 100mV at full accessory
load. If the block ground (where the alt gets its reference)
and battery are not the same then you can lose voltage
at the battery and at the loads. Anything that returns
current to the sheet metal ground can similarly suffer
when chassis tie points get crusty. Block to firewall straps
seem to get hurt, loose or forgotten a lot. And everything
corrodes eventually.