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Dead Battery...


Brent Zier
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OK, I tried to charge my phone for about 30 minutes (accessory on, not running, headlights off). That 30 minutes killed the battery.

Got a jump, OK after that.

Then I played with programing keys. You do this with just the ignition on, car not running.

10 minutes later battery was dead.

Put my charger on the car, OK since - as long as the car is running.

Stopped by FORD and was told the electronics will drain the battery in no time, FORD recommends for their mechanics that they hook the car up to a power source when working on it.

Really? I am not sure I believe this....

Brent

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Interesting. I have had issues with my 06 GT-H. This past summer I got a brand new battery (original was still in it, so it was time to replace). I would drive the car one weekend, and then maybe not be able to drive it for 2, maybe 3 weeks. I would go to start it, and it wouldn't. Why in a few weeks, or month at tops, would that happen? Something is draining it. I too asked a Ford dealership about it and they said if you know you're going to let it sit for a while, put a battery tender on it. Really?! For a couple weeks? Doesn't seem right. I put a tender on it for Winter storage, but a car should be able to sit a month, hell, even 2-3 months and not have to keep a trickle charge going to it.

Any other thoughts/experiences/advice?

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I had to replace the battery in mine in 2009.  I put a Die Hard in it then.  Used them in many other Mustangs over the years and always worked great.  I have never had a vehicle with a warranty before and it did not even occur to me that it was probably still under warranty until about 3 days later.  Lesson learned...  That battery lasted about 7 years.  Towards the end, it would "drain" more quickly. I replaced it with a stock  Mototcraft battery about a year ago and haven't had any issues.  I don't drive it a lot, it has had about 11,000 miles put on it in a little under 10 years.  I try to at least start it every couple weeks and put a 50-100 miles on it a month. 

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2 hours ago, 06H014 said:

Interesting. I have had issues with my 06 GT-H. This past summer I got a brand new battery (original was still in it, so it was time to replace). I would drive the car one weekend, and then maybe not be able to drive it for 2, maybe 3 weeks. I would go to start it, and it wouldn't. Why in a few weeks, or month at tops, would that happen? Something is draining it. I too asked a Ford dealership about it and they said if you know you're going to let it sit for a while, put a battery tender on it. Really?! For a couple weeks? Doesn't seem right. I put a tender on it for Winter storage, but a car should be able to sit a month, hell, even 2-3 months and not have to keep a trickle charge going to it.

Any other thoughts/experiences/advice?

All modern vehicles have "slave loads", e.g., security systems and the like, that while draw low currents (100s of milliamps) do present an active load on the battery.  Does your Mustang have a security system?  Unlock the doors from the clicker?  ETc.  All of those things take electricity and will drain the battery over time.    I always kept the Shelby GTs and Ford GT on a battery tender.  I forgot to connect the SGT up once and it wouldn't turn over after about two weeks (accessories would come on but not enough ooomph for the starter).

Some people disconnect the battery during winter storage but be aware that doing so will reset the computer and require you to run the full drive cycle to relearn all of the adaptives.  This will cause you to fail emissions test if your test is the OBDII "system readiness" type of check (as is used in California and Nevada and other states now)

 

 

Edited by twobjshelbys
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22 hours ago, twobjshelbys said:

All modern vehicles have "slave loads", e.g., security systems and the like, that while draw low currents (100s of milliamps) do present an active load on the battery.  Does your Mustang have a security system?  Unlock the doors from the clicker?  ETc.  All of those things take electricity and will drain the battery over time.    I always kept the Shelby GTs and Ford GT on a battery tender.  I forgot to connect the SGT up once and it wouldn't turn over after about two weeks (accessories would come on but not enough ooomph for the starter).

Some people disconnect the battery during winter storage but be aware that doing so will reset the computer and require you to run the full drive cycle to relearn all of the adaptives.  This will cause you to fail emissions test if your test is the OBDII "system readiness" type of check (as is used in California and Nevada and other states now)

 

 

Yes,  I was the lucky automotive electronic technician for ten years. Everything  twobjshelbys said above is correct.. Welcome to the world of technology..Cars are meant to be driven every day now, not sit.... 

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Can this "slave load" kill a fully charged battery in 10 minutes under the accessory load? I am talking about a car that is starting easy, full battery charge & charging at 14.7 v - then 10 minutes without the engine running, it wont crank unless jumped? Brent. 

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8 hours ago, blz57 said:

Can this "slave load" kill a fully charged battery in 10 minutes under the accessory load? I am talking about a car that is starting easy, full battery charge & charging at 14.7 v - then 10 minutes without the engine running, it wont crank unless jumped? Brent. 

Could be a bad battery (cell) have you done a load test on the battery itself? 

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56 minutes ago, shelby001 said:

Could be a bad battery (cell) have you done a load test on the battery itself? 

I will do that at the local auto parts store. The Ford dealership was not inclined to check it at the time I stopped by.

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On 1/20/2018 at 4:16 PM, twobjshelbys said:

All modern vehicles have "slave loads", e.g., security systems and the like, that while draw low currents (100s of milliamps) do present an active load on the battery.  Does your Mustang have a security system?  Unlock the doors from the clicker?  ETc.  All of those things take electricity and will drain the battery over time.    I always kept the Shelby GTs and Ford GT on a battery tender.  I forgot to connect the SGT up once and it wouldn't turn over after about two weeks (accessories would come on but not enough ooomph for the starter).

Some people disconnect the battery during winter storage but be aware that doing so will reset the computer and require you to run the full drive cycle to relearn all of the adaptives.  This will cause you to fail emissions test if your test is the OBDII "system readiness" type of check (as is used in California and Nevada and other states now)

 

 

Something else to think about besides what Tony has stated is that when ever you access anything in the car either with the remote (locking/unlocking, opening the trunk...) or just by opening the door, it will energize all the onboard computers, so if your radio was turned on when you shut off the key, the radio computers will be running until they go through a "not in use" cycle and shut themselves down. This could take some time and will also drain the battery quicker. Make sure the radio is turned off before you turn off the key.

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I hook a Battery Tender to my 07SGT year around (it is hardwired w/the plug tucked under the front fairing). Just replaced the original battery last spring because the Battery Tender went bad while in winter storage.  I suspect if it had not failed, I'd still have the original battery.

Have another '07 sports car with factory original battery and load tested it-shows 48 more months. 

Can't stress enough to use a tender. 

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41 minutes ago, ChicagoChris said:

I hook a Battery Tender to my 07SGT year around (it is hardwired w/the plug tucked under the front fairing). Just replaced the original battery last spring because the Battery Tender went bad while in winter storage.  I suspect if it had not failed, I'd still have the original battery.

Have another '07 sports car with factory original battery and load tested it-shows 48 more months. 

Can't stress enough to use a tender. 

:yup: I use a tender myself. Just replaced the original battery last summer. Wouldn't hold a charge anymore. I wasn't gonna bitch about 10 years on an factory battery.... replaced it with another Motorcraft. Hoping for another 10 years!

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Is there a brand and part number battery for my 2017 that has way more CCA then our Ford one that is 390 CCA that is an exact replacement so that the battery cover will still fit over battery and basically the outside of the battery is the same size? Was thinking on the lines of a battery with more CCA and total amps on the thought of taking much longer to have car powered systems from pulling enough power from the car that it won't start. We really do have a pretty weak battery. I have a battery tender that works well. But would like to have a much more beefy battery if possible. Thanks

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