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View Full Version : how far on battery + dead alternator?


kamus
12-08-2007, 01:07 AM
if i think my alternator is screwed, and i fully charge the battery, and then start the car by rolling down a hill (to save the charge) how far can i drive before the battery dies?

I wanna know if I can get it to my prefered shop to check/replace the alternator.

And what if I start with the ignition - how far then?

supernaught
12-08-2007, 11:34 AM
not far, and a lot less than not far if you use the starter, maybe nowhere.

supernaught
12-08-2007, 11:35 AM
CAA is cheap I just got a car towed 160kms no $$ out of my pocket

Quack
12-08-2007, 11:37 AM
anywhere between 10-20 mins, maybe more if you're lucky

ThatOneM42
12-08-2007, 11:56 AM
if ur battery light comes on when you turn on ur car, its most likely ur alternator.

if ur goin to do it, turn off ur cdplayer, headlights, try not to use ur brake lights or signal lights lol...this might help you just a bit more. or just be safe and get CAA.

T.Dot_E30
12-08-2007, 01:00 PM
It's very risky and impossible to tell how far for sure.

Either take a chance or play it safe and have it towed.

thatguy
12-08-2007, 01:03 PM
easy disconnect the fuses for almost all the accessory for the car except the DME. u should make it very far, 1-2hour drive.

Axxe
12-08-2007, 01:45 PM
I made it 40 mins home on a dead alt and a dying battery. It ran out of juice 2 KM from home :(

kamus
12-08-2007, 06:46 PM
I have CAA but have already used them 3 times this year, twice for me and once for a friend.

Also is this a valid test: If I get the car started, and then disconnect the battery - a 'good' alternator would keep the car running right? So that might tell me it's the battery that's screwed.

The reason I'm not sure which is because this battery sat dead for the six months while waiting for my recent engine swap. And if these questions sound silly, it's because I don't have a voltmeter etc. to do the obvious :D

Thanks everyone!

e30_kid89
12-08-2007, 06:56 PM
No No! I hear pulling the battery while the engine while running can fry some electronics...

BmW1819
12-08-2007, 07:03 PM
hook up a multimeter when your car is just sitting there it should be around 12.1- 13.0 volts start your car it should jump to at least .5 more than it start for example it starts at 13.0 volts it should at least charge to 13.5 . that's just a quick test

calegrant
12-08-2007, 10:54 PM
I'm experiencing a few battery/alternator issues ATM but I'm not sure how to distinguish who the culprit is. When I start it at 630 am around 0 degrees the lights are really dim, when I give it gas they go to pull brightness. When the rpm's drop down to idle the lights dim as well. After about 5 minutes the problem goes away. I"m assuming it's battery related because of the cold but thought I'd ask to be sure.

craz azn
12-08-2007, 11:22 PM
^ Voltage regulator

BmW1819
12-09-2007, 01:30 PM
^ Voltage regulator

agreed :)

calegrant
12-09-2007, 08:48 PM
The voltage regulator is located behind the alternator and is a simple replacement correct? If I were to go down to lordco is there a specific part # I'd need to have, I assume bosch would be my best bet for a replacement.

Mystikal
12-10-2007, 04:22 PM
The voltage regulator is only external on the Bosch alternators. My car had a Valeo, and no one told me of this difference.

I still have a brand new Bosch regulator sitting here from 4 years ago. lol.

Jay

T.Dot_E30
12-10-2007, 05:12 PM
I still have a brand new Bosch regulator sitting here from 4 years ago. lol.

Jay

Which shop did you show upto asking them to change it? :D

Mystikal
12-10-2007, 06:39 PM
Shutup, I spent 10 minutes in my garage staring at the Bentley manual, then looking at the afternator, then back at the book, and so on.

Jay

kamus
12-11-2007, 02:07 AM
update:

I decided to get a new battery. Because no matter how long I charge the old one, it only manages to start the engine once. So I figured that's effed anyway.

New battery is obviously great at repeatedly starting the engine. But I guess I won't know if the alternator is still screwed for "some time" yet.

Thanks folks! (I'd get a multi-meter if I knew where to stick it:D)

PS: Then something new happened - see new thread!

T.Dot_E30
12-11-2007, 10:21 AM
Take it to a shop and get it tested, it doesn't take long, and most shops shouldn't charge you.