Strange voltage problem
09-26-06, 07:18 AM
#1
Strange voltage problem
I have a new battery and a reman alternator, I show a full 14v at idle with all accessories including defrost, and about 14.4 - 14.5 at 1500rpm with a DMM, however, the in dash gauge never goes over 13V at 1500 RPM with no accessories, and less than 12v at idle with all accessories, accessories are lights, heater CD player and defrost. So obviously this is a problem with the grounds going to inside the car, well at least thats what im guessing. What wires should I be looking at to fix this problem.
BTW, the lights in the dash dim and the voltage drops when going to idle as well, also when applying the brakes (lights obviously) however I dont think it should be this low of a drop when I still have 14V at the battery/alternator.
BTW, the lights in the dash dim and the voltage drops when going to idle as well, also when applying the brakes (lights obviously) however I dont think it should be this low of a drop when I still have 14V at the battery/alternator.
09-27-06, 09:35 AM
#4
Engine, Not Motor
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It may not be a grounding problem. First, take a look at this:
http://www.aaroncake.net/rx-7/grounding.htm
Secondly, look at the wire that runs from the alternator terminal to the fuse box. It's likely corroded and burned. Replace it with good thick 8 gauge wire and new terminals.
http://www.aaroncake.net/rx-7/grounding.htm
Secondly, look at the wire that runs from the alternator terminal to the fuse box. It's likely corroded and burned. Replace it with good thick 8 gauge wire and new terminals.
09-28-06, 01:30 PM
#7
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Have you verified the low voltage problem with another voltmeter?
If you are reading 14V at the battery, you are probably fine.
10 gauge is WAY too small. 8 gauge is the smallest you want with the alternator lead and leaving the stock one in place is useless. Electricity always follows the path of least resistance so the stock lead does nothing if you have added a 2nd. Unless the 2nd is too small of course so it's resistance is too high under large currents, in which case you have two leads that are useless.
If you are reading 14V at the battery, you are probably fine.
10 gauge is WAY too small. 8 gauge is the smallest you want with the alternator lead and leaving the stock one in place is useless. Electricity always follows the path of least resistance so the stock lead does nothing if you have added a 2nd. Unless the 2nd is too small of course so it's resistance is too high under large currents, in which case you have two leads that are useless.
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10-25-06, 01:52 AM
#8
Ok, I know this is an old thread, but my positive battery wire going to the terminal came loose in the terminal one day, and when this happened, by voltage was magically where it should be inside the car at 14v or so, does this mean the regulator wiring is bad? What should I do?Could I set up a relay from the ignition switch to send the battery voltage to the alternator when I turn the ignition swicth on? Or should I send the voltage from another point in the car? Perhaps the voltometer reading itself?
10-25-06, 07:08 AM
#9
Originally Posted by TehMonkay
Ok, I know this is an old thread, but my positive battery wire going to the terminal came loose in the terminal one day, and when this happened, by voltage was magically where it should be inside the car at 14v or so, does this mean the regulator wiring is bad? What should I do?Could I set up a relay from the ignition switch to send the battery voltage to the alternator when I turn the ignition swicth on? Or should I send the voltage from another point in the car? Perhaps the voltometer reading itself?
10-25-06, 11:17 AM
#13
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I dont understand your philosophy. Thats like saying that having two resistors wired in parallel would yield the same resistance as having one resistor, when that is definitely not true. If you have two wires, reguardless of the guage, shouldn't they both deliever electricity to wherever directed? By using a precise ohm-meter, two wires in parallel would appear to have less resistance, and therefore the amount of amps it could pass would be greater.
Pertaining to the voltage meter, isn't there a chance that the amount of resistance from the length of wiring from the battery/alternator would reduce the voltage from ~14v to ~12? Though the grounding location may not be far from the unit itself, the electricity has to flow through a large length of wire carrying the positive charge(most of which is of a higher guage wire=more resistance).
I could be wrong on these points; I am using knowledge from another application since I just purchased my first car not too long ago.
Pertaining to the voltage meter, isn't there a chance that the amount of resistance from the length of wiring from the battery/alternator would reduce the voltage from ~14v to ~12? Though the grounding location may not be far from the unit itself, the electricity has to flow through a large length of wire carrying the positive charge(most of which is of a higher guage wire=more resistance).
I could be wrong on these points; I am using knowledge from another application since I just purchased my first car not too long ago.
Originally Posted by Aaron Cake
Have you verified the low voltage problem with another voltmeter?
If you are reading 14V at the battery, you are probably fine.
10 gauge is WAY too small. 8 gauge is the smallest you want with the alternator lead and leaving the stock one in place is useless. Electricity always follows the path of least resistance so the stock lead does nothing if you have added a 2nd. Unless the 2nd is too small of course so it's resistance is too high under large currents, in which case you have two leads that are useless.
If you are reading 14V at the battery, you are probably fine.
10 gauge is WAY too small. 8 gauge is the smallest you want with the alternator lead and leaving the stock one in place is useless. Electricity always follows the path of least resistance so the stock lead does nothing if you have added a 2nd. Unless the 2nd is too small of course so it's resistance is too high under large currents, in which case you have two leads that are useless.
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