Battery charging Explorer Ltd 02 V8

[baillie]

My battery only gets charged up to 11.8. If i leave the interior lights or radio on for any lenght of time the battery will not start the vehicle. I purchased a new battery specified for a Explorer, and still it only gets charged to 11.8. So i recharge the battery using a 8 stage CTEC smart charger. The Ford dealer has removed the Alternator and has had checked reporting it is okay. With the vehicle idling and with all electrics on including high beam i measured the current coming out of the alternator at 13.8volts.The dealer commented that 13.8 is within spec, and the battery must be the problem, Ford has no idea why i should have a problem and they can't find a TSB. Returned the battery to supplier who recharged it and load tested it and found no problem and fit for purpose. So i wondering if you had a suggestion on why i would having this problem with a under charged battery? The vehicle has travelled 110,000km's. Regards Michael from New Zealand

 

[Number4]

The alternator should charge in the 14 volt range on a drained battery. Though, this may only be checked at driving speeds as idle will not produce the required charge. The battery is considered drained around 12.25 volts (something like that) and the volts tested with a volt meter are just surface charge volts. The real test for a battery must be a load test. There will be a draw on the battery from the ECM at all times. Two months could "kill" the battery. There is a post in this forum about testing for parasitic draw. Look for it to see if you have more than the normal draw rate.
You may also have a bad ground, bad ground cable or bad positive connection/ cable.
Cables corrode on the inside at times, hard to spot but will often crackle when bent. A corroded connection isn't always visible to the eye.