Random battery drain issue - radio or amp or?

[hogges]

Hi,

I know this is not a new topic, random battery discharge while parked with our 2006 4.0 convertible. I read several of the threads here and I was just wondering if there was a definite conclusion on this issue? Multiple threads point at the Shaker unit, but also some voices for the subwoofer amps in the back seat, and some pointers to a control box in the lower right footwell.

Our problem seems to be happening more frequently after riding the car in the rain.

I just found our car again drained to nothing after it was parked for a week. This is an expensive car if I have to get a new battery every year, not to mention the lack of reliability. Happy to fix what needs fixing if I just knew what exactly it was.

Thank you!

 

[86GT351]

Hi,

I know this is not a new topic, random battery discharge while parked with our 2006 4.0 convertible. I read several of the threads here and I was just wondering if there was a definite conclusion on this issue? Multiple threads point at the Shaker unit, but also some voices for the subwoofer amps in the back seat, and some pointers to a control box in the lower right footwell.

Our problem seems to be happening more frequently after riding the car in the rain.

I just found our car again drained to nothing after it was parked for a week. This is an expensive car if I have to get a new battery every year, not to mention the lack of reliability. Happy to fix what needs fixing if I just knew what exactly it was.

Thank you!

There will never be a difinitive answer here becaus eevery vehicle is different. Need to start doing some electrical testing.

 

[Juice]

How long does the car sit between usage?

You have to do is determine if the drain is abnormal. There will be some drain, and a good battery will discharge in a few months if the car is not started or put on a trickle charger.

 

[golkhl]

If you suspect the Shaker head unit to be the drain, remove all cd’s and turn radio off before shutting off the car. This happened on mu 08, it was a bad cd changer that would drain the battery.

 

[TheGanzman]

Also, if you have ANYTHING plugged into the 12V power accessory plug(s), make DAMNED SURE that those items are unplugged when the car is off. At least on my 2008 Bullitt, those plugs are "Hot" even when the car/ignition is off...

 

[Monkeyporn]

I've got het same issue My 09 GT battery dies in three days if not started. I've replaced the Battery more times than I can count. I don't ever leave anything on there nothing in the cigarette light plug or the 12 volt as you young people call it. I don't have any Idea where to even start

 

[hogges]

How long does the car sit between usage?

You have to do is determine if the drain is abnormal. There will be some drain, and a good battery will discharge in a few months if the car is not started or put on a trickle charger.

It seems totally random. Sometimes it has sat for weeks without issue and then it may drain the battery within three days at another time. We make sure to not leave any charger plugged into the cigarette lighter adapter.

 

[VGMStudios]

Like mine, you have a parasitic draw. You need to find out what's causing the issue and I recommend buying a battery charger. If my car sits for more than 2 days, it's dead. There are many videos on YT that explain how to find the draw. Here's one of my favorite ones. He goes into depth about it.

 

[hogges]

Like mine, you have a parasitic draw. You need to find out what's causing the issue and I recommend buying a battery charger. If my car sits for more than 2 days, it's dead. There are many videos on YT that explain how to find the draw. Here's one of my favorite ones. He goes into depth about it.

That's a really well done video. Thanks!

 

[VGMStudios]

You are most welcome. Good luck.

 

[Juice]

It seems totally random. Sometimes it has sat for weeks without issue and then it may drain the battery within three days at another time. We make sure to not leave any charger plugged into the cigarette lighter adapter.

It may seem random, but it really depends on the battery's state of charge, as there is ALWAYS some drain (normal). When it sits for weeks and starts, the battery was likely fully charged. When it dies in a few days, battery could have been partially discharged.

The simplest way to get an idea is using an automatic ~1 Amp trickle charger. If the trickle charger can keep the battery full, chances are there is not a parasitic draw. (Not a fan of lighter socket charging on these computerized cars)

Measure battery voltage with the negative cable disconnected.
Fully charged battery should read 12.6-12.8 volts.
Fully discharged will read 11.8-12.0 volts.
Time to gather some data.

 

[TexasBlownV8]

Something I've found to be an major cause is the battery itself! How many of you with issues are using a motorcraft battery? (not many I would guess). I used to have the issue now and then, kept replacing batteries with good auto-parts store brands, but they would all 'fail' early, and without warning sometimes, after anwhere from 1-3 years, even though the batteries were supposed to last 6 years or so.
Now, I only use motorcraft batteries in my and all family-owned Mustangs, and have not had any issues since. One car sits for weeks at a time without running, and it starts up everytime now, and no trickle charger connected. Another sits up to 2 weeks, and now always starts even sitting that long; whereas before, either of these Mustangs might not start after the first week, when using other good batteries.
Cost-wise, motorcraft's cost less than those store-brands. And, never expect a 'neverstart' to last a long time !

There is always some parasitic draw on power, as the security system is on always and takes a little power. The other 2 major common causes are : leaving the shaker radio turned on when turning off the key (always power-off the radio before powering-off the car); and, leaving something plugged into the cigarette lighter, such as a phone charger.

 

[Juice]

I ended up with Wallyworld batteries in my cars. Just happened that way. 1st one died about a month ago, it lasted over 10 years. Two others going on 5 years.

 

[hogges]

Well here is my workaround to the battery drain for now. This is a remote controlled switch. No need to open the hood to disconnect or reconnect the battery.

I don’t want to get rid of the stock Shaker 500 radio at this point, the most likely culprit, as I like the classic look. Sure, a touch screen Apple car play unit would offer some nice features such as navigation, Spotify, Bluetooth etc. but one thing I really enjoy about my Mustang is the overall retro feel.

 

[Autokyrios]

Just an additional thought to the above stuff....What security pack do you have? If it has the active security and it sits outside, they like to eat batteries. Every time it's alerted to movement (people, parking cars, animals, leaves...dust) it'll power up and cause a drain. If it sits a lot more often than it's driven, it'll eventually kill a battery. Fought with this for years till I got that figured out.

Also, a disconnect will stop a drain, but don't forget it will also clear your throttle pattern and if you have an auto it'll clear that as well, so the car will have to run some miles to re-learn things again each time, and it's a good way to introduce some bad habits into the self learning.