New battery already bad??
2013 Ford F-150 5.0. I replaced the battery Friday. Started the truck up great for the rest of the day. Started up fine Sat AM, but after sitting at work all day Saturday, it kinda slow cranked...
Forum Discussion
patperry2766 wrote:
I can't fathom two separate batteries being bad, but stranger things have happened.
Did you ever fully charge that second battery with an external charger ?? (Third time suggesting that).
At this point, I would want to see the charging voltages for myself......not that I don't trust "mechanics" these days to do that.
AND if both of those things checks out, then you need to look for excess parasitic drains.....like a dome light left on, just for instance. Or a diagnostic scanner left plugged into the connector.....or something left plugged into a cigarette lighter socket that is hot all the time.
It is also possible for a shorted diode in the alternator to drag down the battery when everything is supposed to be OFF.
