I have a 2001 f150 supercrew 4x4 with 5.4L and everytime I drive at night all my lights pulsate they go dim to bright very fast the headlights is more noticable? I just put a new Napa alternator in about 4 weeks ago because the other one died the battery seems OK maybe I should replace it? Please help Thanks!

 

Replace the battery, if it's original it's due. If the lights still flicker, check your grounds.

 

If it started after the new alternator I would be very suspicious of it!!!!!!
Also if it's the origonal battery, get rid of it.

 

put a load test on the battery. napa should be able to do this for you

 

The battery is the original I just can't belive it made it this long it is 6 years old going on 7! The longest lasting battery I have ever had only made 5 years! What is the longest battery life you have seen and what brand was it?

 

My original in my 96 Windstar went 2 months short of 8 yrs.

 

my 97 f150 just got a new battery in august of this year. old one was original. 10 yrs and it still started the truck. granted i was beginning to have electrical issues with it. as soon as i put in a new battery, all was well. well...until this latest bit of problems with either a blown plug or bad exhaust, not sure yet.

 

Yup...same here. I replaced the origional battery in my '97 this past spring. 10 years and 1 month from the build date. I blame it on my Subwoofer and Amplifier for killing it though. I also had to replace the stock alternator a couple monts after the battery.

 

i replaced my 99 f150 battery last week, i installed a motorcraft battery. i will use the original in the shop. still holding a charge

 

Mine lasted a little over 7 yrs. Big/multiple amps killed it early I guess.

 

replaced mine this summer. original with over 200k on 'er. Only replaced for prevention purposes, still good enough for the derby car!

 

My lights were doing similar things and the problem was in the connectors. They actually melted the plastic housing causing loose connections which caused them to change from dim to bright to off. Good luck