[nbpt100]

My battery light went on today and I can't say for sure what the issue it.
I did read the Battery tutorial posted by Stickey. Nice resource.

I drove home, about 15 miles on the highway with all accessories off. The light never went out.

When I got home I did the following measurements:

Battery open voltage with the engine off is 12.7v. That indicates a full charge at 40 degrees F.

The voltage across the battery terminals while running at idle is 14.4 volts.

I know in the past it I have measured 14.5v or even 14.6v. Still 14.4v is still a good charge being put out by the alt.

When I put the lights at idle it stays at 14.4v.

The connections on top seem good. The battery is one year old. The water in the cells are covering the plates.

Any ideas?

 

[nbpt100]

Ok....What should the voltage be at idle?

I need to get a helper to check it at 1500 rpm.

For some reason the light went out. Strangly, it has been even colder with temps around 20F.
Go figure.
Thanks

 

[nbpt100]

Now the light is back on again.

The battery voltage at idle was 14.6 and when I put on all of the accessories including the high beams it drop to about 14.5.

Have not had time to check all of the grounds/connections but those near the top with easy access seem ok.

It is too damn cold to have to deal with this right now.