E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > General E46 Forum

General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 2 votes, 5.00 average. Display Modes
Old 12-23-2010, 02:27 PM   #1
Sixracer
Registered User
 
Join Date: Apr 2009
Location: Boston
Posts: 103
My Ride: '01 325xiT, '85 M635
Minimum voltage to start car?

Hey All. Left my lights on the other day and killed my battery. It is now on my charger being charged but I want to get on the road. I am wondering, what is the minimum volatage for a stock battery that will start the car? Any ideas?

I am wondering if I can pull it off the charger at 12.3 V or so and still start the car? Dont want to bring it out and install it and then find out It isnt charged enough.



I did see this, but not sure how low I can go.

Open Circuit Voltage (12 V) Approximate charge
12.65 V 100%
12.45 V 75%
12.24 V 50%
12.06 V 25%
11.89 V 0%
__________________
...................2001 325Xi Touring..................1985 M635Csi..................
Sixracer is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 12-23-2010, 05:53 PM   #2
kbsilver
Registered User
 
Join Date: Feb 2004
Location: North Brunswick, NJ
Posts: 621
My Ride: 2000 328i
You cannot tell by voltage alone if a battery will start a car. The battery needs to deliver a few hundred amps to crank the engine, that is the more important factor. Condition/age of the battery has a lot to do with it. If you are not sure, wait a little longer. When the car is acually cranking battery voltage will commonly dip as low as 8-9 volts in a properly working system.

Last edited by kbsilver; 12-23-2010 at 05:54 PM.
kbsilver is offline   Reply With Quote
Old 12-23-2010, 08:37 PM   #3
nk_zhp
Registered User
 
Join Date: Jun 2009
Location: Boston
Posts: 720
My Ride: ZHP / E30 M3
+1^. Voltage with no load tells you very little.
__________________
'04 330i ZHP - OEM Clears - ///M Strut bar - CoolantSnitch
nk_zhp is offline   Reply With Quote
Old 12-23-2010, 09:28 PM   #4
jdstrickland
Registered User
 
Join Date: Apr 2010
Location: Murrieta, CA
Posts: 6,793
My Ride: '94 325iC & '00 323i
I guess I don't understand the question.

Put the jumper cables on, or put the charger on, and start the car and hit the highway. The battery will charge in a half hour under most conditions. If you are planning on a drive of a couple of hours, then the battery should fully charge by the time you get there.

How do you leave the lights on? My car screams at me with an annoying buzzer that tells me the lights are on and the door is open and the key is off. Pretty hard to miss it.
jdstrickland is offline   Reply With Quote
Old 12-23-2010, 10:48 PM   #5
Sixracer
Registered User
 
Join Date: Apr 2009
Location: Boston
Posts: 103
My Ride: '01 325xiT, '85 M635
i live in the city so no outlet near car. Had to pull batt and throw on my charger in apartment. I got it to 66 percent, about 12.5 V and started no problem.

i am really suprised i miss the buzz. I had a bunch or stuff to unload and live near the airport. Maybe there was jet noise right when I got out. really wierd.

i understand the whole amp thing quite well but on a good battery, all you have is a volt meter to know if it will work or not.
__________________
...................2001 325Xi Touring..................1985 M635Csi..................
Sixracer is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 04:59 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use