Ford F-150 battery light


Asked by Jul 19, 2013 at 07:21 PM about the 2000 Ford F-150 XL 4WD Extended Cab SB

Question type: Maintenance & Repair

Hi:  When I accelerate medium to hard in my 2000 Ford F-150, the battery light comes on.  When I take my foot off gas or lighten up on gas, the battery light goes off.  Any ideas what this might be?

7 Answers

Going to call this one as a bad ground...corroded 1/0 battery cable as it leads to ground....Battery is older than five causing the alternator to work overtime to supply a battery that is reluctant to take a charge...yes, get a New battery, wirebrush the main Ground connection...fuel, ignition and the ECU all use this ground connection...kinda messes it up because the starter motor is always asking for 300 amps through this connection, yet the ECU perhaps uses 1.5 mA~ if your battery is NEW and Fresh would say tighten the belt or replace the tensioner and arm and idler bearing (in a kit)~

3 out of 3 people think this is helpful.

Thanks for your answer Judge_Roy. What are the chances that it is the alternator itself? The battery is about six years old, but it is one of those Optimax batteries (AGM) and I think its life expectancy is longer than a traditional battery.

1 out of 1 people think this is helpful.

You could test the output of the alternator to see if it is performing okay...Noise is the main concern...if it is worn out will be noisy~ 12.5- 15.0 volts is what the regulator should be putting out~

oops 13.5 to 17 volts bad~~~


I had this happen to me with a thunderbird doing the same thing, alternator tested good until the RPM's came up then the brushes started what they call bouncing, it happens when the rotor contact rings become slightly egg shaped and cause the brushes to lose contact with the rings at higher speeds, replaced the alternator and the problem went away. You might also check your belt tensioner and serpentine belt for good measure as the tensioners are know failure items.

1 out of 1 people think this is helpful.

On newer vehicles the battery light will come on when the alternator is overcharging as well as when it's not charging at all. HTH. -Jim

1 out of 1 people think this is helpful.

Could your alternator belt be slipping some upon acceleration?

2 out of 2 people think this is helpful.

Your Answer

Add photo

Related Questions

  • Ford f 150 won't start 3 answers

    I have a 1989 Ford F 150 and have replace the battery, starter, alternator, and water pump recently. It will run for a day or so then the battery acts like it is dead and won't start? Any idea what...

    1989 Ford F-150 STD Standard Cab 4WD LB


    Maintenance & Repair

  • ford f 150 10 answers

    I have a beeping noise that sounds a lot like the seat belt but it is coming from under the dash,I had my coil replace and was wondering if my truck needs to be reset or something

    Ford F-150


    Maintenance & Repair

  • My 1990 Ford F-150 2 answers

    I have a 1990 ford f-150 5.0. It stopped running at a stop sign and we had come to the conclusion that we though it was the solenoid connected to the fender. So, i replaced the solenoid and when i pu...

    1990 Ford F-150 S LB


    Maintenance & Repair

  • 1994 f 150 battery is charged lights radio work but wont turn over hear fuel pump and click to attempt but nothing after that? 1 answer

    1994 f 150 battery is charged lights radio work but wont turn over hear fuel pump and click to attempt but nothing after that?

    1994 Ford F-150 XLT SB


    Maintenance & Repair


Looking for a Used F-150 in your area?

CarGurus has 216,697 nationwide F-150 listings starting at $1,500.


Search Ford F-150 Questions

Ford F-150 Experts

#1 OJ
Reputation 6,020
#2 dandyoun
Reputation 3,900
#3 tennisshoes
Reputation 2,300
View All

Related Models For Sale

Used Chevrolet Silverado 1500"
2,448 Great Deals out of 144,749 listings starting at $1,995
Used GMC Sierra 1500"
1,025 Great Deals out of 56,906 listings starting at $2,300
Used Dodge Ram 1500"
521 Great Deals out of 13,734 listings starting at $995
Used Toyota Tundra"
618 Great Deals out of 26,786 listings starting at $2,500
Used Ford F-250 Super Duty"
441 Great Deals out of 42,971 listings starting at $2,250
Used Toyota Tacoma"
628 Great Deals out of 30,530 listings starting at $2,850
Used Ford F-250"
609 listings starting at $3,995
Used Ford Mustang"
736 Great Deals out of 41,064 listings starting at $900
Used Ford Explorer"
1,363 Great Deals out of 71,762 listings starting at $300
Used Chevrolet Tahoe"
1,073 Great Deals out of 36,092 listings starting at $1,700
Used Ford Ranger"
263 Great Deals out of 7,704 listings starting at $988
Used Nissan Frontier"
429 Great Deals out of 20,749 listings starting at $2,500

Used Cars For Sale

2017 Ford F-150 For Sale
8,164 listings starting at $17,015
2016 Ford F-150 For Sale
150 Great Deals out of 136,858 listings starting at $16,985
2015 Ford F-150 For Sale
233 Great Deals out of 8,869 listings starting at $17,958
2014 Ford F-150 For Sale
503 Great Deals out of 10,880 listings starting at $10,450
2013 Ford F-150 For Sale
721 Great Deals out of 14,735 listings starting at $7,727