Eating batteries again for the second winter

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ChrisMN said:

Not a parasitic drain problem

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There's clearly a parasitic drain problem. Multiple new Ford Motorcraft batteries won't exhibit the same problem even if there was a rare chance that one was ever a defect. It may be an intermittent voltage drain but you definitely have a drain. It sounds like your dealer is either incompetent or just doesn't want to spend the time to properly diagnose it which unfortunately isn't an uncommon thing in the car repair industry. Just replacing the battery under warranty again and again lets them push off dealing with the real issue and costs them very little.

ChrisMN said:

Perhaps useful details --Ford Leasing Corp. titled this car and was the owner for around 12 months and 900 miles before selling it at auction to the WI dealer. When this problem started it took the dealership a while to realize they were replacing the defective battery with a non-standard battery. During that first 900 miles someone (lessee, lessor???) replaced the factory battery with an AGM battery. Makes me think this car had this problem when it left the factory.

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Exactly, the fact that Ford owned it for 900 miles and sold it at an auction when it was still basically a brand new is a clear indicator to me. For a lease vehicle with 900 miles that's definitely not enough miles to be a daily driver but enough to show that it was driven for a bit is highly suspect. Add that to a new battery having being put in it when the factory battery should last for about 7 years is another huge clue.
There's something that's causing the drain that's affected by the cold but that could be anything really. It could be a bad relay, a bad module, a shorted wire or connection but it needs to be checked with a multimeter, the circuit has to be methodically isolated, and then thoroughly gone thru to track down the source of the problem. It could take quite a bit of time to find the source(hours if not days) which is exactly why a dealer would want to push it off as long as they can.

ChrisMN said:

Ford won't buy the car back because I bought it from a WI dealer and WI lemon law only covers the original owner. More importantly, I love this car and don't want to lose it but obviously it has to run every month of the year.

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Idk what the Lemon Law covers in your state and in your situation but I would look up your rights and try to make them take it back with the help of an attorney. Ford themselves was the original owner and maybe they transferred it to the lease division to try to circumvent the Lemon Law. You could also call Ford customer service and see what they do. Document and/or record everything. If they do nothing then tell them that you plan on going to a friend in the media(be vague obviously) and getting an attorney if the car isn't taken back by them. The idea of having a featured news story about unloading a defective car thru the lease department onto an unsuspecting buyer and a general abuse from a car manufacturer to a helpless owner won't sit very well with them.

Your member ID doesn't say what state you're from(this should be a requirement when joining imo) so I don't know if you're an actual Wisconsin resident or if you just bought the car from there. However, this article details the laws in CA but it does shed light on a lot of the shady bs that car manufacturers try to get away with: Can Lemon Law Cars Be Resold? | Top 3 Questions About Lemon Titles (knightlawgroup.com)

Sounds to me if more than 1 faulty battery your alternator is maybe overcharging and frying internals, not at all? Install inline quick disconnect connection for battery, see if charge is retained by opening circuit every evening. If using Optima theory type batteries very understandable. Entire different set of rules and values with those… cold weather will drain them and won’t charge well unless driven a lot and well drained. Pulse charger only for those to garage charge. My thoughts only, CJ’67 has outlined the master plan.

Cobrajet67 said:

There's clearly a parasitic drain problem. Multiple new Ford Motorcraft batteries won't exhibit the same problem even if there was a rare chance that one was ever a defect. It may be an intermittent voltage drain but you definitely have a drain. It sounds like your dealer is either incompetent or just doesn't want to spend the time to properly diagnose it which unfortunately isn't an uncommon thing in the car repair industry. Just replacing the battery under warranty again and again lets them push off dealing with the real issue and costs them very little.

Exactly, the fact that Ford owned it for 900 miles and sold it at an auction when it was still basically a brand new is a clear indicator to me. For a lease vehicle with 900 miles that's definitely not enough miles to be a daily driver but enough to show that it was driven for a bit is highly suspect. Add that to a new battery having being put in it when the factory battery should last for about 7 years is another huge clue.
There's something that's causing the drain that's affected by the cold but that could be anything really. It could be a bad relay, a bad module, a shorted wire or connection but it needs to be checked with a multimeter, the circuit has to be methodically isolated, and then thoroughly gone thru to track down the source of the problem. It could take quite a bit of time to find the source(hours if not days) which is exactly why a dealer would want to push it off as long as they can.

Idk what the Lemon Law covers in your state and in your situation but I would look up your rights and try to make them take it back with the help of an attorney. Ford themselves was the original owner and maybe they transferred it to the lease division to try to circumvent the Lemon Law. You could also call Ford customer service and see what they do. Document and/or record everything. If they do nothing then tell them that you plan on going to a friend in the media(be vague obviously) and getting an attorney if the car isn't taken back by them. The idea of having a featured news story about unloading a defective car thru the lease department onto an unsuspecting buyer and a general abuse from a car manufacturer to a helpless owner won't sit very well with them.

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I appreciate the complete and thoughtful response. I don't understand how a parasitic drain could fry the battery but I'm 68 and perhaps batteries have changed so much that completely discharging one creates irreversible damage. If that's true, then that goes to the top of my list of possible causes.

I am also thinking there must be a drain in the system somewhere, and it has to be a major drain to kill the battery that quickly. If a battery is repeatedly drained down too low, or if it is drained and left drained for a long time without recharging, yes that will kill it.

Either that, or the charging system is over charging the battery, and killing it that way.

And either way, I'm surprised that the Ford dealers can't figure out what is going wrong. That suggests there might be something more complicated going on, that I don't understand.

I'd probably have someone diagnose it for parasitic drain before going any further. You can do this yourself by disconnecting the negative battery cable, then putting an ammeter in line between the post and the negative terminal, to see if any current is flowing when the car is turned off. A shop with diagnostic equipment can to it better. But it seems obvious that they would have already checked this, so that is confusing.

Cobrajet67 said:

Your member ID doesn't say what state you're from(this should be a requirement when joining imo) so I don't know if you're an actual Wisconsin resident or if you just bought the car from there. However, this article details the laws in CA but it does shed light on a lot of the shady bs that car manufacturers try to get away with: Can Lemon Law Cars Be Resold? | Top 3 Questions About Lemon Titles (knightlawgroup.com)

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That's weird you can't see I'm from MN, it is in my member ID. And, I've spent considerable time on this with Ford customer service in Detroit and been given the brush-off unfortunately.

JBert said:

I am also thinking there must be a drain in the system somewhere, and it has to be a major drain to kill the battery that quickly. If a battery is repeatedly drained down too low, or if it is drained and left drained for a long time without recharging, yes that will kill it.

Either that, or the charging system is over charging the battery, and killing it that way.

And either way, I'm surprised that the Ford dealers can't figure out what is going wrong. That suggests there might be something more complicated going on, that I don't understand.

I'd probably have someone diagnose it for parasitic drain before going any further. You can do this yourself by disconnecting the negative battery cable, then putting an ammeter in line between the post and the negative terminal, to see if any current is flowing when the car is turned off. A shop with diagnostic equipment can to it better. But it seems obvious that they would have already checked this, so that is confusing.

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Dealer has checked multiple times for parasitic drain under different circumstances including keeping it for a week once. And keeping it outside in the cold to match the circumstances of my unheated garage. As to overcharging, that's been on the list also, but I am told a fault code should get thrown when that happens. And they' done whatever diagnostics can be done on the alternator. I think the dealer is making a good effort. I keep trying to come up with a scenario under which the battery is getting repeatedly drained without me knowing it and can't do that. Car starts fine and then 12 or 14 hours later it doesn't at all. As a good MN, I'm pretty sensitive to the noise a starter and solenoid make when the battery is starting to go and I've been getting no warnings. The ideas are much appreciated!

As I said you have an intermittent voltage drain happening. It simply has to be caught in the act but unfortunately the timing is everything and so you need to have the car basically ready to be tested and disconnect circuits one by one when it does.
If you decharge a battery down below about 10.5v a few times and especially to zero then it will typically render the battery unable to hold a charge.
Does Draining a Car Battery Damage It? – Home Battery Bank
Discharging a Car Battery Too Far Can Really Kill It (lifewire.com)
Multiple battery replacements over an extended period of time rule out any possibility of a bad batch. Ford sells and uses a lot of batteries in a very short time as well so you'd be extremely unlikely to get one from the same batch as one that you got a few weeks before.

Cobrajet67 said:

Your member ID doesn't say what state you're from(this should be a requirement when joining imo) so I don't know if you're an actual Wisconsin resident or if you just bought the car from there. However, this article details the laws in CA but it does shed light on a lot of the shady bs that car manufacturers try to get away with: Can Lemon Law Cars Be Resold? | Top 3 Questions About Lemon Titles (knightlawgroup.com)

Click to expand...

Cobrajet67 said:

As I said you have an intermittent voltage drain happening. It simply has to be caught in the act but unfortunately the timing is everything and so you need to have the car basically ready to be tested and disconnect circuits one by one when it does.
If you decharge a battery down below about 10.5v a few times and especially to zero then it will typically render the battery unable to hold a charge.
Does Draining a Car Battery Damage It? – Home Battery Bank
Discharging a Car Battery Too Far Can Really Kill It (lifewire.com)
Multiple battery replacements over an extended period of time rule out any possibility of a bad batch. Ford sells and uses a lot of batteries in a very short time as well so you'd be extremely unlikely to get one from the same batch as one that you got a few weeks before.

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Hello Cobrajet67, Thanks for sticking with me on this. I think you're correct that somehow we have to catch it discharging somewhere, somehow. Nothing else makes sense. And that it is a discharge problem and not an overcharge problem. What I was having trouble understanding is how a single discharge below 10 volts or even down to 2 or 3 will ruin the battery. But your analysis and sharing the two links got me thinking that what must be going on is that with the colder weather there is an intermittent discharge that maybe takes the battery to 70 or 80% (before I start it again in 12 hours or so) and after that happens several times, then the battery dies 'suddenly' even though the intermittent parasitic draw has been weakening it over time. Good news is the dealer has had it for a week and they aren't just storing it. Bad news is this is the same drill last winter and the source was never found although we all thought replacing the BCM in April was going to solve it. I don't know enough about car electronics to know what could fry the BCM and the battery if both are the result of the problem and neither is the cause. Other choice, of course, is that there are multiple problems showing up only in cold weather, which is kind of weird. I feel like I'm trying to diagnose a malfunctioning 1990's computer with Windows 95. Thanks again for your time on this. I'll let you know what the dealer finds this time around if I ever get it back!

ChrisMN said:

I purchased my 2020 Mustang GT March 2021 with only 900 miles. November 2021 (getting cold here in MN) it started eating batteries. I'd go to start it and nothing, battery was under 3 volts and nothing would come on much less the starter. Not a parasitic drain problem -- a dead, destroyed battery that couldn't be charged. Dealer did the usual diagnostics and kept replacing batteries every 2 to 4 weeks and went through FIVE of them. All under warranty but a big pain because sometimes even the tow guy couldn't get a jump going and it's not pleasant to watch your new baby getting cranked onto a tow truck in the snow. Never any fault codes or clue as to what was going on except a dead battery that would not hold a charge. April 2022 the last battery went dead but this time the Body Control Module (BCM) threw some fault codes so they replaced that and Ford told them to put in yet another battery with the BCM swap. Dealer and I were both happy we'd gotten to the bottom of it finally. Mustang ran beautifully until last week (November again!) when the battery was totally dead. Car had been driven for over an hour less than 12 hours before I tried to start it. Dealer now has the car again and don't yet know what they are going to say this time around.
Perhaps useful details --Ford Leasing Corp. titled this car and was the owner for around 12 months and 900 miles before selling it at auction to the WI dealer. When this problem started it took the dealership a while to realize they were replacing the defective battery with a non-standard battery. During that first 900 miles someone (lessee, lessor???) replaced the factory battery with an AGM battery. Makes me think this car had this problem when it left the factory. The 2020 GT still had a standard lead-acid battery. The last few batteries have been spec batteries, dealership even pulled up the build sheet for this particular car to confirm what went in it and cross-checked with a Ford engineer in Detroit that was helping them with this problem.
Ford won't buy the car back because I bought it from a WI dealer and WI lemon law only covers the original owner. More importantly, I love this car and don't want to lose it but obviously it has to run every month of the year.
I'm thinking somewhere, somehow, something electrical or electronic is happening during cold weather that doesn't happen in warm weather that doesn't throw a fault code but am at a complete loss as to what that might be. Any ideas? Thanks!

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It is a battery drain issue....

The problem if Im not mistaken is in the gauge panel...Theres a similar issue with the Dodge Ram Pickups w/the Hemi too...

Theres a fuse you can pull to verify If I recall too...

Another possibiliy are bad relays that stay closed and refuse to open when the power is cut........Try pulling the relays and if the problem goes away replace them all....Usually a point n aim temp gun will tell you if any relays are hot from being active too.....

The Dodges problem went away when I unscrewed all of the 6 serepate grounding points under the hood on both sides of the unibody and removed the factory paint on the nub face then cleaned the terminals and hooked everything back up and everything was fine and this happened on a 2019 Ram.........

It seems the problem existed because Dodge didnt remove the paint where the grounds were installed when built at the factory......

Good Luck

but the big mystery is: if it is a drain, why can't it be measured?

and how can it happen so quickly? sucking all the juice out of a car battery in a few hours generates a lot of heat somewhere

makes me wonder if it might be something completely different, but I can't think what that would be

JBert said:

but the big mystery is: if it is a drain, why can't it be measured?

and how can it happen so quickly? sucking all the juice out of a car battery in a few hours generates a lot of heat somewhere

makes me wonder if it might be something completely different, but I can't think what that would be

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If it takes 12 hours for the battery to die down then maybe something is turning the ignition on? I know at least in older cars having the ignition in the on position will kill the battery fairly quickly. If something in the ignition circuit is energizing then maybe that's enough to kill it in those 12 hours.
We're assuming that the dealer is doing the correct steps to figure out the problem but knowing how some dealers operate I have my doubts. On the surface the dishonest or lazy ones will still try to make it seem that they're professional.

Cobrajet67 said:

It could be a bad relay, a bad module, a shorted wire or connection but it needs to be checked with a multimeter, the circuit has to be methodically isolated, and then thoroughly gone thru to track down the source of the problem.

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When the drain is happening then the amount of draw being pulled out of the battery should be huge as has been mentioned. The amp draw on a multimeter should be quite noticeable. Catching it in the act is the key but since it's intermittent it will be difficult.
I think that the Ford dealer should have been given specific instructions from the engineering department(if they actually consulted with them) on how to proceed with finding this problem. I have my doubts that they either contacted engineering or followed their instructions if they did.
It seems odd to me that every relay in the car hasn't been replaced by the dealer yet or at least the more suspicious portion of them since they seem to just be guessing anyway. Since checking individual wires would be time consuming I would think that for them changing out inexpensive relays would make sense here. The prime modules in the car, the PCM and instrument cluster, are also highly suspect imo.