Ford F-150 battery light

10

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?
Thanks.

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.
10

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 running...my bad~~~

90,655

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.
64,985

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.
108,725

Could your alternator belt be slipping some upon acceleration?

2 out of 2 people think this is helpful.

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