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View Full Version : Why does the car do this?



Nettlesd
03-14-2006, 09:17 PM
Ok, it's not with the SC but with my daily driver, the Sable. Tanya left the lights on all night and it drained the battery. I put the SC battery in to start it and when I go to take off a battery cable the car dies. I thought that you could take off a battery cable and the car would continue to run.

I want to remove the battery cables from the other battery so that I can put them on the drained battery and drive it around to charge it back up. I can't because the car dies when I remove any battery cable.

What's the deal?

ndoftyme69
03-14-2006, 09:48 PM
does either of the terminals touch the frame of the car when u remove them? my car did that because one of the terminals would touch the frame and ground out or something,but it killed the car,and i would have to hook em back up and restart

Nettlesd
03-14-2006, 09:55 PM
Not that I can see but I will double check for that.

Young-SC-Owner
03-14-2006, 09:55 PM
when you do that it just FRIES your alternator just ta let ya know -tony-

Chrismiss
03-14-2006, 10:03 PM
If it was a deisel it would run without the battery. I know this doesn't really help just thought I'd throw it out there.

ndoftyme69
03-14-2006, 10:05 PM
when you do that it just FRIES your alternator just ta let ya know -tony-
I've only had to do it a few times in different cars so I wouldn't know if it would fry it or not...but I can see how it would be overworked...altho i never had a problem with an alternator yet

Nettlesd
03-14-2006, 10:09 PM
What fries the alternator? Grounding a battery cable, switching battery cables or leaving the lights on all night. I take it you mean grounding the battery cable but it's not very clear in your post.

Young-SC-Owner
03-14-2006, 10:21 PM
what i meant was taking out the battery to switch it, it puts alot of stress on the diodes in the alternator and what they do is only let electricity flow one way and that is to the battery and when the battery isnt hooked up the electricity stays put and just keeps the engine running and all of it backs up..correct me if im wrong but yes ive done it take the battery cable off to see if the alternator is shot but i learned that it really helps speed up the death of an alternator so now i just use a mulitmeter like i said correct me if im wrong thats just my $.02 cents
SC-Ya! -Tony-

J57ltr
03-14-2006, 10:21 PM
If the battery is dead then you need to charge it on a battery charger, if you try to charge the battery from the alternator it pulls too much current for too long and will overheat the alternator and cause it to fail.

If your car dies when you disconnect the battery chances are that the alternator is already shot. Use a volt meter (not the one on your dash if so equipped)and check the voltage with the car running if it is less that 13V then the alternator is dead. This is most likely what causd your battery to be dead if you are just assuming that the lights were left on.

Jeff

J57ltr
03-14-2006, 10:27 PM
what i meant was taking out the battery to switch it, it puts alot of stress on the diodes in the alternator and what they do is only let electricity flow one way and that is to the battery and when the battery isnt hooked up the electricity stays put and just keeps the engine running and all of it backs up..correct me if im wrong but yes ive done it take the battery cable off to see if the alternator is shot but i learned that it really helps speed up the death of an alternator so now i just use a mulitmeter like i said correct me if im wrong thats just my $.02 cents
SC-Ya! -Tony-


It's not going to hurt the alternator. The alternator puts out only what is required of it, no more no less.

Jeff

Young-SC-Owner
03-14-2006, 11:02 PM
it puts out 14-15V all the time, where does it go when the battery is off? stays in the alternator burns up the diodes eventually leads to backfeeding and then bye bye alternator. there is one way to see if your alternator is backfeeding and that is go out to your car when the engine has cooled down and feel if the alternator is warm then bingo..losing volts and bad alternator

J57ltr
03-14-2006, 11:26 PM
I am not real sure what you just said, but the alternator will not be damaged by not having a load on it. If there isnít a load on the alternator it wonít put out anything the alternator is set around 13.8-14.4. Just because it might be generating a small amount of voltage it isnít hurting anything. You can have voltage without current but you cannot have current without voltage. A lot like the faucet on the side of your house, just because it is off there is around 30psi and unless it is leaking then no water flows out. The diodes will not be damaged just because itís spinning, their PIV is way higher than what can be generated, and unless the current through them is higher than they can handle (which it isnít in most cases since the battery is a much larger load than most other accyís in the car) then it will be OK.

Jeff

Nettlesd
03-15-2006, 10:30 AM
This is most likely what causd your battery to be dead if you are just assuming that the lights were left on.
Jeff

The headlights were left on all night and that's what drained the battery.

J57ltr
03-15-2006, 10:43 AM
Then if the car died when you removed the battery cables and they didn't touch anything then the alternator is toast or something is amiss in the wiring causing the alternator not to charge. Use a Voltmeter, this is a must, otherwise you are going to start throwing parts at it and spend more money on unnecessary things. You can find Digital ones for less than 10 bucks at Harbor Freight and such. It may be that the Alternator died and is coincidental that it happened when the battery was drained. You will also need a battery charger, or take it to Autozone and they will charge it for free.

Jeff

seawalkersee
03-15-2006, 11:20 AM
Duane, take the alt to Streeder on 23rd street near Dodgion. Its just east of that little car hop place on the north side of 23rd. He is kind of a hippy dude but will do you right. AND he is cheep. Sometimes it takes a tad extra to fry those things out lilke a heavy charge to fill the batt (espically when your car has 200XXXXXXXXXX miles on it). New alt should fix ya right up.

Chris

LJGriggs
03-15-2006, 01:44 PM
"I put the SC battery in to start it and when I go to take off a battery cable the car dies. I thought that you could take off a battery cable and the car would continue to run."

The battery is an integral part of the electrical system. All of the car's electronics (DIS, EEC, etc) as well as fuel pump, injectors, etc run off the battery. This is done to provide a "clean" constant DC source. It is also why the alternator is constantly "charging" the battery during operation. The alternator "feeds" the battery varying amounts of current, via the voltage regulator, based on the operating load requirements. Without the battery, there would be wild swings in DC voltage to the car's systems. It might be possible to run the car for a short period of time without the battery if the ~~~ and NEG battery cable connections were "bridged/shorted" while the battery was removed, but I wouldn't suggest doing that. The car's electronic control systems would probably take a dump real quick...

seawalkersee
03-15-2006, 10:10 PM
The car needs to see a consistant 5v reference voltage to run. Though if you did this, you could run on the alt alone. The reason for the battery is not for anything other then load spikes such as AC, lights, and other abrupt changes in the system, and of course, starting. The car runs on the charge of the alt while it is going.

Chris

Take the alt to Streeders Man...you will be happy (cause he is cheep AND good).

J57ltr
03-15-2006, 10:18 PM
It's going to be funny when he finds out that the problem is a fusable link or something else. Throw parts at it that's the way to fix it.

Jeff

ndoftyme69
03-16-2006, 12:10 AM
If it were me I'd just go buy a jumppack charge it all night go out in the morning hook it up with the dead battery in and connected,start it up and let it idle for like 20 minutes....disconnect the jumppack...put it back in the box....take it back to the store for a refund...haha...problem solved and no money actually spent...

seawalkersee
03-16-2006, 01:56 PM
I dont think there is a link (still thinking though) on there that would allow it to run on just Batt. power. It would show a problem elsewhere too I believe (like starting). I should say that I have never had that happen............................................ .................................................. .................................................. ...............................................yet ...

Chris

J57ltr
03-16-2006, 02:40 PM
Since this is on a Sable/Taurus, (I have a Taurus) I am not sure on the wiring. I know one of my cars had a fusible link that ran from the ALT to the junction for the main dist. point. I can't remember if it was the El Camino, Lumina, S-10, SC, Taurus or someone elses car, but I ran into this same problem thinking the ALT was bad when it turned out to be a link. I am not saying that this is the problem but it's best to make sure before throwing parts at it. That is why I suggest a meter.

Jeff

seawalkersee
03-16-2006, 03:57 PM
Call me Duane.

Chris