07GtS197
Well-Known Member
Could still be a failing alt. I had one go on my gray 02 years ago. It would start fine after sitting and randomly stop charging and die.
Dead battery after replacing cig lighter fuse
- Thread starter MSTCBRA
- Start date
Just starting to feel confident to take it out again and you post this reply? Thanks, it’s at the forefront of my mind.
I added a laughing emoji but it didn’t show up
Adfalenski
Member
Pull out the Bluetooth adapter when the car is not running and see how long your battery lasts. If it still discharges, it is something else. What else goes through the unswitched(always hot) circuits?
ttocs
Forum's #1 poster
pretty sure the mach amp in the dash does
Bronco2Fan
Active Member
Is this the Mystic that was for sale for ever on the SVT Forum? Guy was from Illinois too, I think, Just curious.
Yes I did this experiment for a week now. Haven’t started it since last Saturday and checked voltage everyday. The battery started around 12.5 and is now at 12.
No. I think that one you’re thinking of was a highly modified one from Joliet area. This one lived most of its life in Arkansas.
ttocs
Forum's #1 poster
half a volt over a week will slowly kill a battery. look under the radio for the mach amp and disconnect it
Yes but it’s better than completely dead after 10 days. Progress! Today is a test drive to make sure the alternator charges at all speeds.
I took it on a 40 minute drive yesterday at a variety of speeds. No issues. Voltage gauge looked good. It was on the R the whole time and only moved down between O and R for a few minutes. Came back and it was high 13s when running and 12.7 when off. I think I’m good!
cobrajeff96
Well-Known Member
Sounds good.
As Vice Grip says “I’ve got updates”. All last season I’d disconnect the battery after driving it because there’s some drain happening while sitting. The alternator would charge properly over the 2,000 miles I put on it. Today I started it for the first time since November and the alternator doesn’t seem to be charging the battery. At idle the battery is at 11.76 volts and the voltage gauge is at the N while driving. No batt light on. Is it time to replace the alternator?
ttocs
Forum's #1 poster
at the very least you can either take it off and have it tested or it isn't as good but still works, vatozone can hook up to it in the car and say if it looks good/bad
cobrajeff96
Well-Known Member
What happens off-idle though? Do you give it a bit of juice and hold for a few seconds? Or is it always just idling?
Not sure your exact setup but factory alternators of this era are notoriously weak at idle. They may be rated for x number of amps but that number fluctuates in the rpm range. And it also depends on the regulator and in the modern era the ECU itself. If I were you I'd take it for at least a 5 min drive, ideally longer. Might change things.
Not sure your exact setup but factory alternators of this era are notoriously weak at idle. They may be rated for x number of amps but that number fluctuates in the rpm range. And it also depends on the regulator and in the modern era the ECU itself. If I were you I'd take it for at least a 5 min drive, ideally longer. Might change things.
ttocs
Forum's #1 poster
it could also be a blown fuse under the hood. Take 2 mins and check all the fuses in the box.
I drove it to get gas. Noticed the volt gauge was lower than it was last year when I knew it was charging. So I got gas and came back home to put a meter on it. I’ll pull it off and have Oreillys test the alternator.
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