2003 mach 1 battery or parasitic drain issues

[briand354]

Hi All,

I am in need of some help .. and have limited resources around me .
I live in massachusettes, where auto stuff is overpriced, and they arent the best at solving issues .
Here is my issue, I have a 2003 mach 1 , auto . It runs great WHEN it actually starts .

The car has a bunch of aftermarket amps in the trunk, now, all disconnected .
I've replaced the battery [at a shop, after asking to check the drain on the battery/no start issues] .
I could have done that myself! Here I am again, a few weeks later with the same issue, with a new battery .
The amps were reconnected, which seemed to coincide w/ the battery having no starting power at all .. [however .. for more info here, the car was never POWERED ON with the amps , just plugged it in for testing .. with an on/off switch .. l and left in the parking lot connected , but switched off ]
previous to that, the battery would start the car w/o issue . Now , even with the amps disconnected from the battery, it seems to struggle, even after running it a bit .
At this point, Im thinking that something related to the amps, or wiring is grounded, causing the battery itself to either a)drain , b)short c) the amp is shorted, thus shorting the battery [im not sure if this is possible .. but i think it could be the issue .. --not sure] .

I put a multimeter on the 'new' battery to find it had 2V left in it . Looking at my graph, it appears that 12.5V is 'good' voltage on a given battery for a vehicle ..

Im not 100% sure the battery issues are related to the amp being connected .. as the on/off switch was for the remote wire, coming out of the stereo to allow the amp to turn on while the vehicle is turned on . All i can concretely say is, the battery worked before the remote wire was connected w/o issue, once it was connected .. [with a switch in the off position] -- my new battery is stone dead w/ 2V remaining .

Is it possible over the course of a week or two the battery would drain , or discharge all the way down to 2V naturally ? I dont have this issue w. my gfs car .. which is driven 'weekly' at least . Does it sound like there is a parasidic drain elsewhere ? Is this common for this year mustang ? Can anyone recommend a repitutable shop in the framingham ma area that could fix this , or at least give me a diagnosis ? Should i go to the dealer ?
Sorry for all the confusion and questions, but in the middle of this quartantine, I need to have my vehicle start EVERY time I get into it . imagine there was an emergency .. ?
Im ready to get rid of the vehicle, .. if I cannot resolve this issue . Please advise, stay safe out there .
thank you for your help in advance .
-B


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[Bullitt95]

It does sound like you have a big parasitic draw, and the likely culprits are the aftermarket amps but don't despair.
There are instructional videos in YouTube on how to test for a parasitic draw. As you perform the procedure, you'll need to pull fuses and relays one by one until you narrow down the problem.
Good luck and let us know what you find.

 

[briand354]

Hi Bullitt95,

I appreciate the response. So, some notes, I think the battery itself is bad .. checking the voltage, its inconsistent at best, but doesnt go above say 10/11V .
From some research i did, it appears to be part of the issue, so i need to get another 'new' battery .. as a first step .
tomorrow, I'm going to pick up a trickle charger.. I have an older barely used battery sitting in my basement , perhaps once i get it charged up , IF it holds a charge .. I may test this again . I'm going to remove all of the aftermarket wiring, and amps, crap, etc . wire wrap/zip tie it all, and then see if i can get it at least running again . I'm 99% all my issues are related to something associated with the after market stuff that was put into the car .
Once its running again, I bought a battery cutoff switch .. while im trying to troubleshoot this .. as someone else suggested .
This has been a problem since i owned the car .. so, i've been chasing this w. a few mechanics for a bit now . . about a year . [give or take time, as i didnt drive it much due to this issue, which i could not have known .. when i bought it ]
The alternator seems to be cool .. from the gauge i have, it does recharge the battery .. otherwise it would not have been able to keep running in the first place ,.
it was putting out 14.2 volts, as expected when running .

I'll update this thread once i get some progress on this ..

give me day ..or two .

Thanks
-B

 

[Bullitt95]

At 10-11v your battery has a dead cell so definitely needs replacing.

 

[briand354]

Sorry for the delay, but i have an update ..
So., I have a new battery exchanged, and installed ! We are rolling again . Before installing, I've disconnected the + battery AMP wiring , from the stereo amps in the trunk . I suspect they are bad . So good so far . I've also installed a negative battery quick disconnect on - terminal . . and have found this to be working well for me . when im ready to use the car, i pop the hood, quick connect the negative, and it fires up .. as expected . This solution cost me $7 .. and 5 mins to install .
Sure, I could chase the drain .. or have a mechanic figure it out .. but during this, and covid .. im not taking chances . Im going to tackle fully removing all of the after market amps/wiring .. when the weather gets a bit cooler . I dont need that crap anyway . . and in EVERY vehicle i've owned that had after market subs, and amps this was always a constant issue .. and this car, seems to be no different . I'm afraid to leave the battery connected for long periods, while the car is sitting [like .. in a parking lot, after i drove somewhere ] .. but I drove around a bit locally .. parked, and then restarted again w/o issue . .. [but i still carry my jumpbox .. no matter what , just in case .. that things saved me so many times! ]
I agreed w/ your assessment, .. battery should be 12.5V , @ normal voltage . mine was 11V, i think it was internally grounded , or just a dud .

so, I will continue to monitor .. and report back . i just got it done this weekend, and have only driven once since installing .. so i need more testing time .

thanks, for your help though . . it did get me to the right direction in solving my issue . ill upload a pic .. of my config, in case someone else has a similiar issue in the future, on how i dealt w/ it .
When things settle down from covid, i'll chase what the drain actually is . Im thinking the amps ground the battery, and then it self drains .
before the amps were connected, the battery [connected] didnt have this issue . we'll see how it goes .. i promise ill do the drain test, along w/ the removal

Thanks Bullitt95

-Brian