Hi guys. Been a while since I last posted. Traded the '97 on an '05 4X4, 5.4L. I've finally reached 8,000 miles. As you can see it gets babied. My question is that the amp meter guage never goes to the + side (charging). The battery was low and it is 2.5 yrs old so I am expecting it's reached it's life expectancy. After I got it started I expected to see the amp meter guage fly to the charging side big time. Didn't happen. Is this normal? While idling, I can turn on lights and the needle will dip to discharge, but even if I rev it the needle never goes above the middle indicator. The alternator seems to be working. If I drive it for 30 minutes or so it charges the battery and cranks over great.
Trying to avoid taking it to the dealer and asking....You know what they will recommend.
Any help??
Thanks
Jim

 

how are you measuring your amps? in order for you to be able to read what your alt. is capable of puting out you would need to load the system with a AVR. if your battery is in good condition your alternator isnt really putting out that much without a load.

 

I am judging this by the amp meter in the instrument cluster on the dash.

I also have an '80 Corvette. After it sits for 3-4 weeks without running, when I start it the amp meter needle goes over to the right (+) indicating it's putting out additional amperage to charge the battery.

The F150 amp guage needle isn't doing that. Just sits in the middle.
Hope this helps.

 

your f150 has a amp meter?

i think ur confusing the volt/battery meter with it.

the needle should b hovering around the middle, meaning its at the proper voltage, not to low or too high.

 

That could very well be. Wouldn't be the first time I've been confused. It only has a picture of a battery. The older units, as I recall, used to say ampheres not volts.
Hovering is exactly what I would expect. As I mentioned, it does dip slightly to discharge when I turn on the lights but never goes above the middle when I think it should be charging the battery.
If the battery just barely turns it over before it starts it must need a charge.
I'm assuming I will also need a new battery. I envy the guys here that are getting 4-7 years out of a OEM battery.

 

Helps a lot!

The guage in your truck is a voltmeter, not an ammeter. If the alternator is doing it's thing properly, you should be seeing a reading that is close to 14 volts. (On the guage, this is about halfway). It will NOT go far to the right or to the left unless the alternator is bad). If the voltage is low or high, your alternator is bad.

But, if you have an ammeter, it will show a BIG deflection to the right (high amps) when the battery is low and needs to be charged. Once charged, the ammeter will move back to the "zero" level (probably in the middle of the meter) indicating that the battery is no longer taking a charge. And, if it is over to the left, you are discharging the battery - your allternator/generator is bad.

I always thought ammeters were easier to understand, but no one consulted me before the changeover.

I'd say your battery is bad. Have it load tested and replace it if it is bad. A bad battery can ruin an alternator.

- Jack

 

Jack, Thanks.
That's exactly what I wanted to know.
The voltage guage is hovering in the middle. I'll be getting a new battery first chance.
Thanks also for the definition/difference of amp meter vs volt meter.
Jim