battery light
 

When I accelerate fast like up a on ramp to the highway my battery light comes on.

what causes that?

slipping belt maybe? alternator going out? battery problem?

what do i check and how?

start ur car disconnect the battery it should stay running if not ur problem is the alternator.

DONT DO THAT.. ur battery acts like a surge superssor... u could f**k up a few things if it is not the alternator
go to advance auto parts we do free full charging system checks usually about 5-10 min to test

no incorrect the battery is only to START the car. its not like saying keep it disconnected the whole time u go out somewhere.

One Simple Battery Test:



1) Connect the voltmeter directly across the "Battery Terminals". (NOT to the Cable Clamps)

2) While watching the meter, Start the Car.

3) The Battery Voltage should Never fall below about 10 Volts.
If it does:
a) The battery is either "Low in Charge".

b) Or The Battery is "Low in Water".
(The water leven in the battery should be about 1/4 of an inch, Above the Plates.)
"DO NOT" Fill it up FULL.

c) Or The battery has a "High Internal Resistance".
(Possibly Sulfided Plates and probably Time for New Battery?)



**NOW Repeat This Test BUT:

1) Connect the voltmeter directly across the "Battery Clamps on the Battery Cables".

2) This Reading should be Within 0.1 Volt Maximum, the Same as 3 Above.
***If NOT, Clean Battery Terminals and Clamps.

2a)If Necessary, Repeat Test to Varify it is now OK.



**NOW Repeat This Test Again, BUT:

1) Connect the Voltmeter Directly Across the Positive Terminal of the Starter and it Case Ground.

2) If the voltmeter reading is More than 1/2 Volts Lower than the Previous Test,
** You Probably have a Cable or Connectorp Problem!
Check the Connections between the Cable and the Cable Connectors. ON BOTH ENDS.




One Very Simple Alternator Test:



1) Start Car and run at a normal idle.

2) Connect a Voltmeter Directly Across the battery Terminals.

3) Turn on Headlights to High Beam.

4) check the battery Voltage.
*** The Battery voltage Should read between about 13.8 to 14.2 volts. (Possibly up to 14.5 Volts.)

5) Increase motor speed to about 1500 RPM. The Alternator should now produce a battery voltage between 14.2 and 14.6
Volts.
*** If it is Lower than 14.2 volts, the Alternator probably has one or more Bad Diodes.

6) Now, Maintain the 1500 RPM and Turn off the Headlights. Run this test for One Full Minute.
"The Battery Voltage should NEVER Exceed about 14.8 Volts".
***If it Does, the Alternators Voltage Regulator is probably Faulty, OVER CHARGING the Battery.




These Test are "Meant to be a Guideline". The Voltage Measurements above may not be accurate in all cases.

For Example: "A Bad Starter Could Easily Pull the battery BELOW that 10 Volts".

It is Impossible to take into account, All Possible Situations.

I still don't know why the battery light would only come on at acceleration.

why does that happen, anyone seen this before?

see above response? check it out and see if that tells you anything

I think either your battery is dead or you have a bad alternator. The battery light is lighting for one of two reasons. Either you have a problem with the charging system (which includes everything) or you have a problem with the associated sensor. What I would do is have my battery tested first to make sure it is in fact good. If that checks out then I would get the alternator tested. If it is bad I would go for a bigger one since you have to replace it anyway.

Thanks i'll have it checked out.

The official info...

so what youre saying is when under acceleration it might be under/over charging.

ya, have it checked out

or for some reason the voltage regulator is signaling to the PCM through the "f" terminal that there is a problem.

took it to the zone yesterday and the battery checked out good.
he thinks the voltage regulator is going bad because it went from a peak of 140 amps to 1 amp fluctuating all through the test.

So i guess it's time to change the alternator and they aint too cheap.

The Cliffster nailed it.

Well like I said if you got to get a new one then you might as well go bigger.

mralternator.com has one(high output) for i believe 250, with a lifetime warrenty...

thats more than at autozone.

I don't need to go bigger, no real advantage for me.
I can spend 125 at the zone and get a lifetime warrenty.

today the car stalled and died while driving and i hadn't changed the alt yet, so i did today after that !
while it was off i had it checked again and this time it checked good and they told me their other machine had been acting up lately and could have been wrong the last time i had it checked.
so i put it back on and had the battery checked and it also was good.

took it to the dealer and the ehad mech said it all checked out good too.

But after i got it home i found out something very important, the light that came on before wasn't the battery light at all it was the low coolant light ( looked like a battery)
I chewcked the coolant tank it it was very low, added water to it and now i'm hoping that it's ok now.

Ha, I remember when my low coolant came on and I looked and couldn't tell either. Took me three times to see it before I realized it had to be coolant bahaha.