Two issues with pre-purchase inspection

[10basetom]

So I'm in the process of buying a 2011 Mercury Milan Hybrid and took it to a mechanic for pre-purchase inspection. Everything is fine with the car except for these two issues:

1. Starter battery failed load test (see attached photo). I'm surprised by this because I can see from the service records that the owner had the car serviced at a Ford dealership a few months ago and they replaced the battery. I'm also confused by the "no start" result because I was able to start the engine just fine during the test drive and the drive over to the mechanic's shop the next day.
2. At one point in the past the OBD had triggered a P0A7C-00 code. Even though this code is no longer active, should I be worried? The mechanic advised the owner to ask Ford what they did to resolve this code, if anything. According to the description, common problems that trigger this code can include:

• Converter failure
• High voltage control module failure
• Hybrid transaxle assembly failure
• Motor electronics coolant temperature sensor failure

Yikes! To be fair, when I test drove the car, it was very smooth and silent, and I didn't see any warning icons in the instrument panel. Still, the fact that this code was triggered once before worries me.

 

Please let me know if I'm just being paranoid or if these are potentially serious issues that I should have the owner look into before completing the purchase. This would be the first time I have ever owned a hybrid or a Ford/Mercury vehicle, so it's a big deal and I hope that everything works out because I really dig this car :D.

[murphy]

12.28 volts is about a 60% charge on a wet cell lead acid battery. It also indicates it was tested in the vehicle. If it wasn't disconnected from the car the test is invalid.

 

A 100 amp load test or a CCA test both require the battery to be fully charged. My CCA tester will not test a battery that is not fully charged.

 

The 12 volt battery does not start the engine. It activates the contactors that connect the High Voltage Battery (HVB) to the car. The engine is started by one of the high voltage motors.

 

If the 12 volt battery gets too low, all bets are off. All kinds of false errors can be generated if the modules on the bus are not at there operating voltage.

 

The battery should be fully charged and then load tested. With a 100 amp load it should stay above 11 volts for at least 10 seconds.

Edited August 26, 2018 by murphy

[10basetom]

12.28 volts is about a 60% charge on a wet cell lead acid battery. It also indicates it was tested in the vehicle. If it wasn't disconnected from the car the test is invalid.

 

A 100 amp load test or a CCA test both require the battery to be fully charged. My CCA tester will not test a battery that is not fully charged.

 

The 12 volt battery does not start the engine. It activates the contactors that connect the High Voltage Battery (HVB) to the car. The engine is started by one of the high voltage motors.

 

If the 12 volt battery gets too low, all bets are off. All kinds of false errors can be generated if the modules on the bus are not at there operating voltage.

 

The battery should be fully charged and then load tested. With a 100 amp load it should stay above 11 volts for at least 10 seconds.

 

Hi murphy, thanks for the info! I will ask the mechanic on Monday whether he fully recharged and removed the battery before testing. The fact that he referred to the battery as "the battery that starts the engine" suggests maybe he's not familiar with servicing hybrids.

Edited August 26, 2018 by 10basetom

[lolder]

The code has occurred a few times in older FFHs in hot, high speed cruising conditions. I vaguely recall there is a reprogramming of the motor/electronics cooling pump speed to correct this. Only Ford could have done this and they should have a record under the VIN number. Check with a Ford dealer.

Also, if you buy the car, treat it to a new 12 vdc battery no matter how it tests. It is the weakest link in the whole system.

Edited August 27, 2018 by lolder

[10basetom]

The code has occurred a few times in older FFHs in hot, high speed cruising conditions. I vaguely recall there is a reprogramming of the motor/electronics cooling pump speed to correct this. Only Ford could have done this and they should have a record under the VIN number. Check with a Ford dealer.

Also, if you buy the car, treat it to a new 12 vdc battery no matter how it tests. It is the weakest link in the whole system.

 

Thanks lolder, I'll be sure to take it to the Ford dealer after I buy it to ask them about this code.

 

Regarding the battery, I'll leave it in for now since it was just replaced by Ford only a few months ago. When it comes time to replace the battery, I found this video that was very helpful:

 

 

Instead of going through all that work to modify the battery tray, someone in the comments mentioned a group size 96R battery is a perfect match for the Ford OEM battery, so no modifications necessary.

 

UPDATE: I just got off the phone with the mechanic and confirmed that they did not remove the battery and did not fully charge the battery before doing this test, so I will skip replacing the low voltage battery and hope for the best. If there is indeed a problem with the low voltage battery, then that battery icon should appear in the instrument panel, right.

 

UPDATE 2: I got the battery inspected at the Ford dealership and they confirmed that it's defective. Since it was just replaced in March, they replaced the battery with the one in the photo free of charge :-).

Edited September 5, 2018 by 10basetom