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I started a thread since I have more data about our battery issues. Twenty months ago the dealer replaced our Motorcraft battery with a Motorcraft Max battery, and also re-flashed the trunk module.  That seemed to have cured a recurring dead battery issue (the third battery since 2015). We road trip the car often plus some local trips, so it's not just a short-trips-only situation.  I also use a battery tender if we expect prolonged down time.  In fact I used the Battery Tender to juice up the battery before our trip.

 

After a recent 500-mile road trip where we drove the car often at our destination then drove 500 miles home, the battery was completely dead after just a few days in the garage. Went to wash it and no start, no dash lights, nothing.

 

A voltmeter I can read while driving shows 14.5 volts at start-up. This quickly drops to 12.8v to 12.9v at idle. Voltage while driving seems week at just 13.1 volts. When decelerating the volts bump up briefly to 14.5v then they drop to 12.8- to 12.9v while idling at a light.  With ignition OFF, the voltage reading drops quickly 12.5v >>> 12.4v >>> 12.3v >>> 12.2v.  This afternoon the at-rest voltage was 11.9volts so there is a draw somewhere.

 

Bluetooth is turned off, no phone is paired, and our 3G modem was disabled by Ford in February (but could that modem still be trying to connect to something)?

 

In two weeks I have an appointment for the dealer to check the alternator, and belt tensioner. Am I missing anything else?

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If your key was near the car and the welcome light feature is enabled, that could easily do it. You'd never notice the lights if its out of sight in the garage.

 

The voltage readings dropping that quick after shutdown probably indicates the battery was left drained for too long and has lost capacity. Or being almost drained over a longer time period. Sometimes the standard Ford chimes activating when keying-on are an indicator of this... for some reason.

 

I  would replace the battery and then monitor the voltage again in the same scenarios you did above. Be sure to reset the BMS battery monitor with forscan if you do as this controls the charge rate of a new vs old battery.

 

One thing I have noticed is that when I get out and lock the car at night, the touch screen stays on, but its black. Its hard to notice unless you specifically look for it. It stays on for like 5-10 minutes or so, possibly longer. If I open up the door (happens to be the passenger door) and then close it and re-lock, it USUALLY turns off completely. In this scenario, I'm usually removing hockey bags from the trunk after I get out, close the trunk and lock the car, and notice the ghost black screen on the way by.

 

I have heard that pressing the brake after you key off prevents this but I don't think there's any merit to that. I too use a tender if I don't plan to use the car for a week but make sure you attach the negative clamp on the charger to the vehicle ground and not the battery negative.

 

One last aside... there was also a massive stretch of bad batteries and you might not have any issue with the car. There are only a few manufacturers but tons of branding names so going to another brand likely makes no difference.

Edited by 02LincLS

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Thanks, 02LincLS.  We store the key inside the home, several rooms away from the garage.  I do pay attention to the center screen - the Lincoln logo does fade to black pretty soon after opening and closing the door.  Am still compiling a spreadsheet of voltage data under different conditions. Will post when I have more data points.  I will say that instead of seeing 14.x volts on every start-up and drive cycle, there are times when the voltmeter is only showing 13.2 volts. That does seem to be within range of PCM management, though. Our other cars (2005 Subaru's) run at a constant 14.x volts.

 

The difference when we take road trips is opening and closing all the doors and trunk quite a few times in a given day compared shorter a local trips on my own. But we don't run all the features like AC, nav, stereo, and lights the way some drivers might. 18 months ago we had the dealer reflash the trunk module that seemed like a solution (and install a new battery) - and it may have been - but I may have waited too long (5 days) to drive the car again after our 1500 mile trip.  

 

The question is how Ford/Lincoln will handle this if the car is brought to them with a charged-up battery and not towed in dead. 

 

 

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They'll charge a diagnostic fee to stress test the battery and that's about it. Advance auto can do that for free I believe if you buy a battery. In order to get any good info, you need a known good battery. If your battery drops to 10V while cranking, its done.

I don't know all the details of the BMS but I don't think it would be abnormal to see less output from the alternator if the car deems charging not required. There is info online though how it works.

 

Only real way to know what might be draining it is monitoring current draw overnight, and unplug one module at a time, probably starting with the trunk. Then the ACM or whichever one runs the touch screen (maybe the FCIM after that). The car should be in a pretty deep sleep mode by the 30 minute mark. And remember, things like the display don't always stay on. Just because a module looks good one night doesn't mean its not the culprit. Amp probes with data logging come in handy for this stuff, and even then can take some time to find.

 

I got one of those Yaber YR800 lithium jumper packs and it cranked over the tiny engine without issue so I always keep it in the car. I put a Diehard AGM battery in even though I don't have stop/start. Its about a year old but with colder weather here, we'll see what happens. I noticed it seems to not crank quite as quick is it did in the summer. I suspect the screen still. However to support the trunk module idea, I don't use the trunk much in the summer. Fall, winter and spring though there's constant use with kids hockey bags etc. I'll have to see if I can update my module through forscan.

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I busted out the laptop and my obd link (wired usb adapter forscan approved for programming modules) and noticed a couple things. While I reset my BMS when I put the new AGM battery in last year, I didn't update the battery type. It was still set to the original. Another setting is that the car targets just 80% rate of charge. I use my car for 45 minutes and it was not charging it to 80%, it was sitting around 70%. Maybe it waits to a certain threshold before charging or it has to sit deep sleep for 8 hrs to update? Anyway, I updated the battery type and set the target charge to 90%. I will charge it with a battery tender, then remove it and let the car deep sleep for 8 hrs (locked, and no interaction for 8 hrs including nearby key fob) so BMS can account for the fresh charge.

 

I did reset the BMS which is not desirable as now the car thinks its a new battery when in reaility its a year old. Its probably not the end of the world. The car is always trying to disable the alternator to gain MPG and these charging issues are the result, in combo with trunk modules and stuff having parasitic drains. I'll try 95% target next after watching this a while, and finally go to 100 if i don't see problems. My car is not start/stop equipped, but these charging targets, parasitic drains, and poor battery quality are the main causes behind those systems disabling.

Edited by 02LincLS

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Thank you for the additional insight. Will post some data after another day of logging values from the smart charger's display.

 

The question I have is why this Motorcraft MAX battery is considered "toast" after less than two years?  Systemic charging issues, or is a bad batch of batteries also involved?

Edited by jmcgliss

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If the battery is left barely charged, it builds up sulfates on the plates. It basically reduced the size or capacity of the battery because the lead isn't exposed to the acid. So you can charge it to 12.6 V but it discharges too quickly due to reduced capacity. Sometimes the battery can be revived by hitting it with a high amp charger which removes some of the sulfates, but it will never be as good as it was.

 

I could easily be wrong here, but on the bad batteries, I think individual cells were soft shorting so instead of 6 cells at 2.13V, you basically had 5 at 2.13v. Sulfating can cause this, but poor manufacturing was more likely the culprit. You'd easily spot this with low voltage so I doubt this is the case for you.

 

Heat is also the enemy so make sure to have the blanket on the battery. My LS had the battery in the trunk and those lasted 8 years without any attention. AGM batteries are more susceptible too so I need to get a insulating blanket on mine.

 

I hooked my 5A battery tender up but it basically was in maintain mode after a couple minutes. The car sat long enough it should have updated the state of charge but it was at 71%, and 74% after 45 minute drive. Whole thing is beginning to really irritate me because when the battery is full, the car audibly turns over faster. Its not confidence inspiring to hear its not as fast as I know it can be, and the cold winter is right around the corner. The stupid BMS also encourages sulfating as a result of its strategy. Add in trunk modules and touch screens staying on and here we are with 1 year battery life.

 

EDIT: Here is a great explanation of the BMS system... https://f01.justanswer.com/dcraig1000/7f13f1f7-c45e-4508-9ecf-45e8de351e0f_eee.pdf

Edited by 02LincLS

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Posted (edited)

After logging daily voltage data from August and September I let the Lincoln dealer have a look.  My confidence is not 100% after the service writer said the following:

     "These cars have generators, not alternators" What? It's a 2015 2.0L turbo.

     "We pulled several body module codes that indicate a low voltage condition".  Well, yes. That's why I'm here.

 

The Service Manager called at end of day with the following:

     "The battery tested fine several times" even though last month's QuickLane receipt says "Battery Weak".  The data I provided proves the battery will sag from 100% to 30% in 2-3 days (getting worse).

     "There is virtually no draw...like .02 to .03 OHMS versus Ford spec of <.05".  That's good news, but he said Ohms, not Amps?

 

Update: With no draw detected they had no TSB's or prior knowledge to go on. And without being towed in dead, they left the battery in place. I do have heat-reflective material to cover this battery, and the next one that I buy. Voltage drop (at rest) is still about .1 volt per day regardless of what their draw in Ohms says.

Edited by jmcgliss

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yeah, seems 90% of them are numbskulls. They probably didn't even test it.

 

So a couple times I charged mine up with the 5 amp battery tender and the car had a 100% state of charge the next morning. At end of first day it was at like 90% and then 80% second day. I think its generally staying around 75% right now. I also reset the BMS when the battery was fully charged so that the alternator (its an alternator even though the obd pid's call it a generator) would charge it more aggressively. The car just doesn't seem to enable the alternator output enough to hit the target soc. I drive at least 45 minutes at a whack so there's no reason target soc shouldn't be achieved. I am going to try to find the updated BMS module software and updated it via Forscan.

 

I have not yet looked for overnight parasitic drains yet.

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I found this site googling what might be wrong with my car. 2017 mkz 2.0 awd.. Originally I thought it was just a worn out battery, replaced it. Dead in a week. Then the dealer said it was a battery sensor.. Replaced that and it was good for 3 weeks. Leave it sitting on Sunday, go out Monday and it's deader than a doornail.. Back to the dealer who doesn't know any more than I do. 

 

I'm not having any trunk issues or any other kind of weird thing whatsoever other than the chimes changing and the battery dying. I need to figure this out lol

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Welcome.

 

You won't notice issues, its as simple as a power draw overnight, or possibly something not going to sleep like it should. Many modules have been accused of being the culprit. Check out this thread on these forums that blames the DDM driver door module and the ACM audio control module. The chimes change because of low voltage so the car is going into a power saving mode, running only critical components.

 

I'm highly suspect of my ACM module because the screen stays on. To provide better detail, I think of the screen in something like 4 stages; 1. Full on and displaying a logo or all white screen. 2. On but displaying no image so its black but brightly backlit. 3. On and no image, but DIMLY backlit. 4. Actually fully off. Given that mine likes to hang out in the #3 dimly backlit black screen mode for 10 minutes even though I locked the door makes it pretty easy to believe it could be drawing power all night long.

 

I also suspect poor charging strategy from the BCM body control module which oversees the BMS battery monitoring system. I have been in the habit of data logging my car since I'm 93 tuned so it was no big deal for me to log the battery state of charge too. By default the car targets 80% so that battery life is extended. I changed mine to 90% target but the car does not appear to try to charge it higher. That's why I think the first reasonable move is to update all the modules and hope it doesn't make things worse. And thanks to the logging, I can use a battery tender to top off the battery if it gets too low in my eyes (under 70% and the car audibly starts slower). The battery is fine because the battery tender gets it to 100%, offsetting the power that a bad module is drawing. Why the car can't hit the target state of charge on a 45 minute drive is beyond me. I'll generally only see it raise like 5% max.

 

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