Alright....my 7 doesn't get driven much...I usually try to start it and run it around the block once a week. Well, for the last 3 or 4 times...each week when I went to start the car, it seemed like the battery was weaker and weaker. Well, this last time I went to start it...the car was completely dead. I jumped the car...and it started up, but I had to stay in the car until it was warmed up (no bac..and won't hold idle when cold)...after the car was warmed up (about 10 minutes), I got out and removed the jumper cables from the 7...as soon as I removed the cable...the fan kicked off...and the car promptly died. Now I was under the impression that even tho the battery was dead, the car should still run off of the alternator. So, how can I check the alternator to see if it is good or bad? Is there any wiring I should check?

 

Time to break out the digital multi meter and check your running voltage.

Voltage while running should be above 13.5 volts, or the battery is not charging.

 

put a charged battery in it an fire it up it should run fine then pull the battery terminal off if it stalls its ur alternator i jus had this happen to me

 

I was under the impression that you shouldn't run a car with the battery unhooked? I'm not sure why...but I remember hearing that it could be bad on the electrical system of the car. Can anybody confirm or deny this?

 

Can I do this off of the jumper battery or do I need to put a new battery in and then test? I ask this, becasue the car dies as soon as I unhook the jumper cables. The wire I'm testing voltage on, is the black/white wire correct?

 

I was under the impression that the battery completed the electrical circuit on our cars. That means nothing happens if its off.

 

It sounds to me like your battery is just totally shot. They get to a point when they just no longer hold a charge, and it sounds like your's is there.

 

^I hope it's just the battery...I've been wanting to pick up an optima redtop anyway...so this would be a good nudge to go ahead and do so...however, I'd like to make sure when I hook it up, that it doesn't have the same fate as this battery.

 

your car should still run after u jump it if u unhook ur cables an it stalls its ur alternator check it with a mutimeter it should read 14.4 while its running wut does ur voltage guage read wen its running

 

The reason I think that its the battery and not the alternator is because even if its jumped, there should be enough juice in the battery to run the car for at least a little bit. Maybe not long, but definately more than a second or two.

 

nope...this thing flipped off like a switch...the instant the cable came off..the fan clicked off and the car died. It's been pouring rain all day here, so I haven't been able to go meter anything. Hopefully, it'll slack up tomorrow and I'll be able to test it. Still...can I test the alternator voltage with the jumper cables hooked up? That's the only way I can get a test with the car running, without spending money on a new battery that I may not need right now.

 

I had the same exact problem a couple of weeks ago. I bought new battery and new alternator........fixed the problem right up, but my charge light keeps coming on and off, but no worries, this will fix the problem

 

adding on, if it is the battery and it has a fried cell, the alternator holds the power and it fries the coils that regulates the power,

 

DON'T DO THAT.

Quickest way to smoke the alternator and the electrical system in the car.

These cars are not some 60's or 70's chevy.

FC's (as well as most cars built after 1982) have internal regulators. If they loose voltage and the alt has any blown diodes or a open regulator (like most german cars and the S5 and later RX-7) the alt can spike out 16+ volts.

Anything over 15.5 volts can smoke the ECU

 

if you just unbolt the alternator and take it to oreillys or advance auto parts they will check it for free. (and if you need one, pm me, ill sell you a good one dirt cheap, i have lots)

 

I swear....my next house WILL have a garage...the rain just keeps coming and coming. I'll check this stuff out as soon as I can, and report back.

 

wow...haha im having charging problems right now too. my story is- after siiting in an hour of traffic yesterday morning with wipers, lights, and defroster on, my car would not start when i tried to leave school. jumped it, and it ran fine. made it home, then left a few hours later and that time it started. wouldnt start again the next time. this morning wouldnt start either. i was looking around and noticed the main wire on the alt. was a little loose, but as soon as i touched it with a wrench, the damn nut broke off. now im trying to find an alternator in the area(nobody has them in stock!!), so i can maybe actually get to school. i took the battery to the auto parts store and they told me battery was bad. thing is, its only about a year old, and its the 2nd one in there in the last 2 years. ughhhhhhh

 

well...I just pulled the alt and battery out of the car...I'm gonna carry it to town, in a while and get them tested...then go from there....the terminals (R and L I think) look pretty rusted/corroded...gonna see if I can find something to get in there and scrape them off some.

 

my battery was tested, and was bad, now ive put in an alternator/battery, and for some reason my main fuse blew. im still trying to get that out now