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BlkMach10510

BlkMach10510

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I had a very comparable problem…. Oe battery died …. Went to auto zone and they sold me a battery called an EFB… this thing would die within 20
Hours of not on a charger, my active exhaust stopped working…. Car was always lose my presets and it was driving me nuts. I had three EFB battery replacements for free within a year. Last time the battery crapped, I had them give me a lead acid battery and it solved every issue I had …. Hope this helps !
I think the Mach 1 has EFB (Enhanced Flooded Battery) as OEM which may be why they sold you that one and why it may be why we have issues with our OEM batteries. Maybe we should have the one you bought as OEM?
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Joe Gonsalves

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The battery you want is an AGM, Absorbed Glass Mat. AGMs are pricy but worth it. This type of battery is like a deep cycle marine battery, where it can get drained low and recover when charged. Unlike a standard lead acid battery, if you drain it too low it can damage or weaken the cells in a process called sulfation. Therefore you need a fancy battery charger that can de-sulfur the plates. Of course this must be done outside the car. NOCO Genius makes chargers that have this feature. Also you may want to check parasitic drain on the battery. Our cars are notorious for having modules running even after the car is off i.e. WIFI and telematics. The BCM Battery Control Module will shut down various car systems in an attempt to hold enough charge to start the car. It never works in the real world. But the BCM can get in your way a lot. So when you replace the battery it is important that you reset the BCM or the car will think you still have the old battery.
 

melwff

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My 21 Mach 1 battery lasted 4 years replaced with Interstate and reset battery monitor at time of install.
When not used for a period of more than a few days use smart trickle charger from Deltran.
 

Mustang Maverick

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The battery charger system is designed to let the voltage fluctuate in a range. If you’re expecting it to hold XX.X all the time thats not how the charging system is supposed to work on these cars. If its not turning over or whatever sure just get a new battery.
I took mine in to my dealer (Blue Bonnet in TX - who has always been great with me) with the same issue - voltage was constantly up and down and fluctuating.
They explained the charging system monitors and adapts as necessary.
Never a problem and I changed my battery at about 4 1/2 years.
Went with the Motorcraft which I use in all my cars - 06 Mustang, Expedition, F150, 370Z, Ralliart, Audi S5, and no problems.
 

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Still running my original motorcraft battery in my ‘19 Bullitt. No issues and it’s SC’d so it puts a bit of a load on the electrical From whait i see from charging readings.
 

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BlkMach10510

BlkMach10510

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I bought a new battery. I charged it to 100%, reset BMS, let it sit for eight hours, and then drove my car around. I think it is good now, accessories mode on 12.5V, car running 14.5V. Seems like ford missed the battery being bad the four or five times I went there and had them check it.
 
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BlkMach10510

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Well, my car is showing 12.0V with my car off. It will show 13.0V then 12.5 V and rest at 12.0V after a total of about 10 seconds total. ford has said nothing is wrong but something has been wrong after I had my car for about five months.
 

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Well, my car is showing 12.0V with my car off. It will show 13.0V then 12.5 V and rest at 12.0V after a total of about 10 seconds total. ford has said nothing is wrong but something has been wrong after I had my car for about five months.
Something has to be drawing from it in excess when it’s off. My 7-8 year old battery is above that still. You’ve got a problem, but it doesn’t sound like it’s the battery
 

Gregs24

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Well, my car is showing 12.0V with my car off. It will show 13.0V then 12.5 V and rest at 12.0V after a total of about 10 seconds total. ford has said nothing is wrong but something has been wrong after I had my car for about five months.
If your battery is at 12v when off it is pretty discharged. When started it should be at around 14.5v until it reaches about 80% charge when it will drop away to about 13v

If your car is only showing 12.0v running then I suspect a BMS or alternator fault?

How much do you drive your car (miles per year) as if it is discharged just driving it will not recover the battery for a long time, you will need an external charger to do that.
 
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BlkMach10510

BlkMach10510

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If your battery is at 12v when off it is pretty discharged. When started it should be at around 14.5v until it reaches about 80% charge when it will drop away to about 13v

If your car is only showing 12.0v running then I suspect a BMS or alternator fault?

How much do you drive your car (miles per year) as if it is discharged just driving it will not recover the battery for a long time, you will need an external charger to do that.
This is a brand new battery that is going to 12.0V too. I am retired so I do not drive much, maybe 20 miles every other or every few days.
 

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Buy a battery maintainer
I have a battery tender and I use it, I was just wondering why my battery loses energy so fast. This morning I did not even hook up the battery tender yet and it was back up to 12.5V even though last night it said 12.0V.
 

melwff

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Have you used a multimeter to confirm accuracy of those numbers?
 
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Have you used a multimeter to confirm accuracy of those numbers?
I have not personally but ford has checked it over about 4-5 times and has said there is nothing wrong with my car's electrical system.
 

Gen 6 Mach1

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I'm confused after reading thru all the posts , I just replaced my battery yesterday, I had the old one on a battery charger / maintainer, for the year I've had the car( 2021 Mach1)while not in use, no idea of the maintenance to the battery prior to my purchase. I must say only during the day the charger/ maintainer is plugged in, before bed I unplug . (The reason why I do this is my neighbor down the street , I'm not sure exactly what happened , but he was in the garage (electric golf cart ) plugged it in or checking on the charge , it blew up knocking him out , started a fire burned the garage killing him . Was a very sad deal 91 years old ) . Anyway my old battery I would check before bed the volts would be 12.5 abouts the next morning down to about 12.3 , plug back in for the day and so on . Fast forward the other other morning it was at 11.9 , plugged in, evening up to 12.4 about's , unplug at bedtime, yesterday morning same routine checked voltage 11.2 volts , only thing I can figure is it finally died . I put a new battery in , reset the BCM drove her around 20 or so miles , this morning 12.7 volts , so I plugged a tender in and it's been red about 6 hrs now and voltage reads 13.41, waiting for the light to go green .
Maybe I worry to much , my other neighbor buddy keeps his car and truck plugged in 24/7 while not in use and sometimes he's gone months at a time .
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