So I drove the Bronco yesterday about 75 miles. I took it off the trickle charger with a full charge and when I hooked the charger back up after getting home, the charger was indicating it was below 80%. This morning, the charger light indicates it’s back to fully charged.

Shouldn’t it have been fully charged after starting the day that way yesterday and then driving it? Anything I can do to test it out without pulling the alternator and taking it into a parts store?

I’m running a 3G alternator and a yellow top Optima.


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Checked numbers with a voltmeter.

Battery at full charge was right at about 13 and with the truck running, I am at about 13.9. I did not have the stereo turned off and I have a couple of amps installed so maybe this is right?

You could try a poor mans load test turn on all the trucks consumers headlights heater and so on. See what voltage you are producing. This wont tell you the condition of the battery but should let you know if the alternator is working.

That's not bad at idle. Let it sit for a couple of days the check the battery voltage. A 2-5 amp trickle charge can take up to 72hrs depending on the rate of discharge.

If it were me, I'd monitor the situation a bit more. You can buy one of those voltage gauges for your cigarette lighter like this:
https://smile.amazon.com/dp/B0773BYS6P/ ... hEbDPN2N82
And just watch it more closely. I'd use actual voltage as opposed to a percentage as well.
Engine off, battery should read above 12v. Engine on, battery should read between 13.5 and 14.5 with a load (headlights, stereo etc.)