Battery light on!

LiftedBlackHD · Aug 6, 2013

Battery light came on last time i drove the truck. I had some time today to mess with it. I cleaned up the terminals and still the light is on.

I hooked up my SCT and it's reading 11.7 volts while running with nothing turned on.

I unplugged one battery and it dropped to 11.4.

I unplugged the other battery and it read 11.4.

I unplugged both batteries and it immediately died.

Btw I am running a 6G 140 amp large case alternator from Quick start that I bought in 09.

The batteries are wal mart specials from 2008.

Any help would be appreciated.

Btw I still have the factory batteries in the garage that i wanted to have refurbished.

97BambiBasherPSD · Aug 7, 2013

sounds like your batteries are poo man.

HeavyAssault · Aug 7, 2013

5 years old....get some fresh juice. I try to change out the batts every 3 years.

Lassie · Aug 7, 2013

HeavyAssault said:
5 years old....get some fresh juice. I try to change out the batts every 3 years.

Me too. It's now a three year maintenance item for me. Gonna try to have batts reach three years old in the Fall of the year too.

HeavyAssault · Aug 7, 2013

I try to do the same thing. Strange thing is my batteries have a 36 mo warranty and tend to fail at 30-35 months. VERY strange.

LiftedBlackHD · Aug 7, 2013

Thanks guys. You believe it is the batteries and not the alternator?

Lassie · Aug 9, 2013

You can have all of these tested for free at most parts stores. Just have to be willing to leave batts overnight for a load test.

No way to tell if alternator is good if hooked to dead battery/batteries. And with their age, they are almost certainly shot.

LiftedBlackHD · Aug 9, 2013

Im just gonna bite the bullet and buy some new batteries this weekend. From now on I think they are going to mysteriously fail every 35 months!

I still have the original set of Motorcraft batteries in the garage. Any ideas of what I can do with those?

Vinny07psd · Aug 9, 2013

You can turn them in for money

stereodesigner · Aug 10, 2013

Mine was doing the same thing yesterday. Swapped out the alt. And im good to go.
You Should be charging at atleast 13v when running

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LiftedBlackHD · Aug 10, 2013

Well I bought two new batteries and i'm still only getting 11.9 volts according to my SCT. Battery light is still on.

I'm assuming it's the alternator. Pretty disappointing because it's a 6g 140 amp from alternator parts from 2009. And apparently they won't give me any credit if I return it to them and by a new one.

loboost · Aug 10, 2013

LiftedBlackHD said:
Well I bought two new batteries and i'm still only getting 11.9 volts according to my SCT. Battery light is still on.

I'm assuming it's the alternator. Pretty disappointing because it's a 6g 140 amp from alternator parts from 2009. And apparently they won't give me any credit if I return it to them and by a new one.

My truck reads around the same but no battery light....I'm certain my batteries are toast...I can fully charge them..and load a tune and they're dead again. I'm going to try a desulfator once before replacing them. If a battery has ever been dead cold for any amount of time ...its hard to bring them back to life.

Lassie · Aug 12, 2013

LiftedBlackHD said:
Well I bought two new batteries and i'm still only getting 11.9 volts according to my SCT. Battery light is still on.

I'm assuming it's the alternator. Pretty disappointing because it's a 6g 140 amp from alternator parts from 2009. And apparently they won't give me any credit if I return it to them and by a new one.

It's very common to lose alternators when a battery drops cells. Just hope it hasn't killed your FICM already too. Now, change batteries every three years and you wont have to buy more alts. :thumbsup:

Redman920-06 350 · Aug 12, 2013

Batteries and Alternators are a common unnoticed/maintained items. No one checks until that little light comes on. Shame really. I had a F150 OBS that had been in the family since NEW, Still had the Factory Installed ALT. LMAO.