Voltage vs. Heat

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Pharaoh XJ

NAXJA Forum User

Location

Cairo, EGYPT

• Oct 14, 2006

• #1

Every morning I start the XJ (94 AW4 HO) the voltage gauge is reading late 13s after 15 mins of traffic the needel drops significantly to early 12s just before the redline. I notice the difference in electricals the horn is much weaker performance is different I notice even more drop with AC on .
I have no amps, no subs just a radio and fog lights which i never use.
I think this is related to heat I tried sealing the battery but still no noticable imprvement. any ideas?

 

MoparManiac

NAXJA Forum User

Location

Amherst, NH

• Oct 14, 2006

• #2

Do any mudding? The alternator could be the culprit if it took in too much crap.

 

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gjxj

NAXJA Forum User

Location

ohio

• Oct 14, 2006

• #3

check the volts directly at the battery with a multimeter. I'm guessing you'll find that it is ok, which would mean you have a connection problem between the battery and the accessories on the car.
Dont know why it would show up after 15 mins, unless maybe thats when your electric fan kicks in.

 

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Pharaoh XJ

NAXJA Forum User

Location

Cairo, EGYPT

• Oct 14, 2006

• #4

gjxj said:

check the volts directly at the battery with a multimeter. I'm guessing you'll find that it is ok, which would mean you have a connection problem between the battery and the accessories on the car.
Dont know why it would show up after 15 mins, unless maybe thats when your electric fan kicks in.

Click to expand...

The electric fan kicks in around 115C but i have a fan override switch .

 

langer1

NAXJA Forum User

Location

Mineral City,Ohio

• Oct 14, 2006

• #5

When you first start up the voltage is supposed to be higher because the battery is being recharged.
After the battery is full it's suppose to fall back to 12v.

Make a test, after the temp is up and voltage is back to 12v, turn the engine off and the head lights on for 5 min, then restart and see if the volts don't go back up to 13+ volts.

 

Last edited: Oct 14, 2006

jeepboy381

NAXJA Forum User

Location

Gresham, Or

• Oct 14, 2006

• #6

I am pretty sure it should be around 14 volts. My jeep does the same thing, when it gets warmed up voltage is way lower but not at the battery. Only further down stream. I am thinking it might have something to do with my clutch master dripping brake fluid on my fuse box possibly!!! Everything under the hood looks fine.

 

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Pharaoh XJ

NAXJA Forum User

Location

Cairo, EGYPT

• Oct 14, 2006

• #7

when I start it its exactly 14 falls down to 13.6 with high beam, fog lights, AC High, AUX fan but need to test when its hot didnt get a chance yet

 

Matthew Currie

NAXJA Member #760

Location

Vermont, land of big clay

• Oct 14, 2006

• #8

If there is a resistive fault in your wiring anywhere, it can increase with heat, so I would suggest that if your voltage is actually dropping at the battery, you check all alternator and battery related connections. If it is not dropping at the battery but is somewhere else, you may have to probe around to see where the drop is occurring.