Battery light comes on

BACK2CHARRIS

MEMBER
FORD EXPLORER

I have a 96 ford exployer with 170k mi. The other day the battery symbol come on and the charging guage was on the low side. I went and had both the battery and alternator checked. They said both were fine. I replaced the battery when it would not start and had to get a jump. After installing the battery, the battery symbol was still on and the guage was reading on high charge. My son looked at it and found a wire from the battery loose on the connection to the alternator. It seemed to run fine.
then this morning after driving about 45 min. All of a sudden that battery lite came back on and it again is charging on high, but only when I give it gas, not when it idles. What in the world is going on here? Can you help please?

2 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Get an analog voltmeter remove the negative battery cable, attach the Black lead to the battery post, Red lead to cable end, then pull fuses one at a time, make sure there are no accessories or lights in the on position, Key off! Close the door after each fuse and check meter, when you pull the fuse for the bad curcuit, the meter will drop to 1 volt or so. Check all fuses, even under the hood. If meter does not drop, remove the battery connection from the alternator, if it drops now, the diodes are bad in the alternator. Put the fuse back in were it goes as you go so you don't forget which fuse goes were! This will find out if it has this Parasitic drain condition, if not hook up the cable and start the truck, with engine running it should produce 13.8 to 15 volts at idle, with all accessories on, it could help if you sent a picture of the wire your son hooked up? If the Battery is overcharging, replace the alternator, no matter what the store testing it tells you! The regulator, which is built in is not regulating!