I have had a 2013 SEL, Equipment Group 303A, for about 1 yr. Two years ago an independent shop replaced the 12V battery with a OEM Motorcraft. Among the service records I received from the previous owners, there is no indication of an earlier battery replacement.
About 6 months ago, one morning I found the CMAX wouldn't start and determined the 12V battery required charging. I charged it for an hour or two using a Sears 12V car battery charger (purchase in the 1960s) using the under-hood contacts. At the time I suspected that the auto-headlight-turn-off feature had failed, and I stopped relying on that feature. Now I wonder if the problem was of the sort addressed by Ford's Customer Satisfaction Program 15B04, which has been discussed on this forum (along with lots of dead 12V battery issues). However, according to Ford's records, CSP 15B04 module reprogramming and wire inspection was done by a Ford dealer on 7/13/15.
Recently I again found the battery voltage was too low to allow the CMAX to start. When I tried to charge it with the Sears charger using the under-hood contacts, as before, the charger's current meter pegged at 7A. I quickly unplugged the charger. Since the charger is only rated for 5A continuous, I limited the current using a high-wattage, 1- or 2-ohm resistor. However, something on the right-hand side of the under-hood equipment then began to click is a repetitive sequence, and the current drawn from the charger changed several Amps in synchrony with the clicking. I found that when I limited the current to around 3A by using 3 ohms, this clicking stopped and the current was constant.
Although it was left charging at around 3A for more than 24 hours, the battery voltage did not increase to the point the CMAX would start.
I was able to recharge the battery by disconnecting the connector from the battery positive post and using the Sears battery charger connected directly to the isolated battery.
A Ford dealership service department reports that the battery has passed their elaborate battery stress test, and they didn't find any reason why the battery voltage was so low in the first place.
Does anyone have any idea what could have been causing the clicking I heard when the charging current was greater than 3A while I was using the under-hood contacts that are there to permit battery charging with access to the battery?
Does anyone have any idea what why I couldn't recharge the battery using hundreds of watt-hours of energy, yet the battery passed the dealership's stress test? It seems the energy must have been dissipated somewhere other than in the battery, but where?
Thanks for any ideas,
David