my battery light goes crazy at 4k rpm
 

i have a 2000 f150 ext cab 5.4 an everytime i hit 4 or 5 thousanf rpms my battery light either turns on or flashes erratically.....why does it do this ......also i recently found out my truck is not running up to par with a 0-60 in 11 instead of the usual 8 or so......it has 70k miles on it and has ENVER had a problem with it...never been in the shop and i wouldnt be able to tell you if the service light worked because ive never seen it on :) and if that was related to my battery light flashing....I NEED HELP!:confused::confused::confused:

u need an alternator.

that makes sense....are you positive thats it?....and would that be related to my power problems at all?

also...how much would it cost to replace my altenator

Belt slipping?

when the light comes on its usually a low battery but when it flashes its a charging problem.

I had this problem with my '03 work truck ... alternator.

thanks you guys i think it is the alternator cause they go out at around 70 and i got 72 so thats probally it....:banana:

Check the belt first. They should be replaced around 75k. My alternator has 120k and is working great.

Yeah I was going to say, I have never had to replace an alternator on a daily driver. You can get alot more than 75k out of them

Knocking on 95K right now...I still have the factory belt on it....I know, I know, I'm on borrowed time....I just need to get a breaker bar...I have a new belt in the back seat.

Alternator still charging at 14.2-14.4 volts (HAM radios make good volt meters! when they have their display up!)

ok so basically its either the alternator or the belts???? correct?

well unless the belt is completly broken or has zero tension...its the alternator

x2, the power steering & A/C performance would have also suffered if it was that loose

But if the alternator is failing his battery would die and he would need a jump start. How long has this been going on?