Battery drained dead

LkySpade

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Ok this is the first issue of my new/used 15 gt. Getting ready for storage and was gonna get some fresh gas but the battery was dead. Remotes didn’t work. It’s been sitting for about 2-3 weeks. But I don’t have any accessories or alarm to create additional draw. Any suggestions? Is this normal?





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cmxPPL219

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It's been talked a lot about, and you're not alone, especially for folks earlier in the year who started driving less due to the "worldwide health issue."

Need a few more details, but as far as you know:

-Is the battery original? If it's a factory unit, and it's been in there since 2015, chances are it's done. (get a load test done to it to find out for sure.) Also, the factory batteries supplied with the car, based on a lot of users seen on this forum who talk about the battery, they'll die in about 3-4 yrs; less if you live somewhere hot. Some even have had a faulty battery new.

-Any other charging system issues?

-Sitting for a couple of weeks is enough to kill it, especially if the battery was already on it's way out. A highway drive once a week (if you are not storing it, which you are, and having a trickle charger) that is at least 20 mins is enough to maintain a charge.

-When you eventually get things sorted out, when you lock the car, use the remote; press lock twice on it till you hear the horn honk. This puts the car in a lower power consumption mode, and prevents the car from continuously searching for the remote. You can never really shut off all the vehicle's modules, but doing this, and assuming the car isn't unlocked or touched again within a certain time window (I believe a few mins) allows the car to go into a lower power state.

-Having no accessories and assuming no intermittent parasitic drain issues that would be caused by them, or another issue, is not enough to prevent a battery from being dead, for reasons above ^

Let us know what you find out.
 

Elp_jc

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First of all, the battery is borderline inadequate for a V8 IMO, let alone one with 12.1:1 CR. And second of all, this car has the worst parasitic losses that I can remember in a long time, so that's a recipe for a flat battery even in a week. My guess is there's nothing wrong with your car (battery might be bad, but I'm talking about the car), but you just can't let them sit idle for so long without battery issues, so I'm just leaving a smart charger connected to my car all the time, something I never had to do before, but there's nothing I can do about that. It is what it is.

If your alternator is putting out at least 13.5 volts (I think 14.0 is the max), there's nothing wrong with it. Keep in mind the BMS (battery management system) doesn't have the best algorithm IMO, but it was programmed for fuel savings. Sometimes it only puts out 12.0V (engine load, etc), which is actually discharging the battery, while saving a minute amount of gas. You could disable it, but then alternator would be putting out 13.5V all the time. I decided to leave mine alone, and just leave car connected all the time when at home. If you're unsure if your system is fine, just get it checked. But if you have a voltage gauge, that'd be enough IMO. Good luck.
 

5-OH

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I bought my car new in 2015, it now only has 7.5k miles, that being said I barely drive it. I live in S. Florida so batteries don’t last down here in hell, and I replaced my original motor craft battery last November. When COVID happened my car sat in the garage from late March until early August, at which time I tried to open it and the battery was completely dead. I used the key to get in and attempted to jump it first which was unsuccessful. I used a charger I have which displayed the battery current voltage as less than one volt. Luckily this is an autozone battery which they swapped out for free. Since then I bought a battery tender and have had zero issues. Even with no accessories on your car, new cars draw a small amount of voltage with all of the electrical components in them nowadays. The keyless start/open remote system is constantly talking to the key, which draws a small amount of power. The only way to stop that while your car is parked is to place the key in a faraday bag or box. This is also a good practice with the way thieves are stealing cars by mimicking the key frequency when they stand outside of your house using a device, that captures your remote frequency while the car attempts to talk to the key.
 
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LkySpade

LkySpade

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It is a motorcraft battery don’t se any date stamp though.
 

BlackandBlue

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A 50ma load will run the average car battery down completely in 2 months. I don’t know what load the car runs off but I would think it’s would be somewhere around that.

Once you take a battery much below 12v the acid will start to eat the lead paste destroying the capacity of the battery. Age also does the same. An old battery at 50% capacity might not start the car after 2 weeks sitting.
 

Balr14

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My stock Mustang GT battery lasts for months if I don't lock the car.
 

Elp_jc

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Reportedly it draws less if locked, but who knows. I never lock it inside the garage.
 

analogman

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In my 2015 GT, the battery would die within 2-3 weeks if the car was not driven. This happened even with a new battery. I agree, the parasitic drain with this car is unbelievable.

Unless you make efforts to drive it regularly, the only solution is a battery tender/trickle charger. I put one on my car a couple of years ago, and leave it connected all the time. Problem solved.
 
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LkySpade

LkySpade

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I was just surprised because my 97 f150 with an aftermarket alarm doesn’t drain that fast. Ty all for the info.
 

ChrisJ

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I have a 19 and it drains the battery in 2 to 3 weeks, tried locking and turning the perimeter alarm off but doesn't seem to help. Just put the battery tender on it when I know its not going to be driven for a while.
 

RPDBlueMoon

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First of all, the battery is borderline inadequate for a V8 IMO, let alone one with 12.1:1 CR. And second of all, this car has the worst parasitic losses that I can remember in a long time, so that's a recipe for a flat battery even in a week. My guess is there's nothing wrong with your car (battery might be bad, but I'm talking about the car), but you just can't let them sit idle for so long without battery issues, so I'm just leaving a smart charger connected to my car all the time, something I never had to do before, but there's nothing I can do about that. It is what it is.

If your alternator is putting out at least 13.5 volts (I think 14.0 is the max), there's nothing wrong with it. Keep in mind the BMS (battery management system) doesn't have the best algorithm IMO, but it was programmed for fuel savings. Sometimes it only puts out 12.0V (engine load, etc), which is actually discharging the battery, while saving a minute amount of gas. You could disable it, but then alternator would be putting out 13.5V all the time. I decided to leave mine alone, and just leave car connected all the time when at home. If you're unsure if your system is fine, just get it checked. But if you have a voltage gauge, that'd be enough IMO. Good luck.
I heard this to about the stock batteries. Are there 'bigger' batteries that have more voltage that you can use to get a better battery?
 

ORRadtech

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I heard this to about the stock batteries. Are there 'bigger' batteries that have more voltage that you can use to get a better battery?
It's not about voltage. All car batteries are around 12.6 volts resting. Bigger batteries are more about reserve capacity than anything else.
 

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