Battery voltage
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Senior Member
Joined: Feb 2011
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C204
Battery voltage
My battery is 6 years old. I used the service menu on the dashboard to access the vehicle data and the battery stats. The key was on position 1 when I checked the voltage and it was 12.1V, then 12.0V.
Does this mean that the battery is ok? What voltage means that the battery is in poor condition and must be replaced?
Does this mean that the battery is ok? What voltage means that the battery is in poor condition and must be replaced?
Senior Member
Joined: Jan 2008
Posts: 373
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From: Vancouver, BC
08 C300
Staying around 12v is good without being charged. Once the car runs, and alternator kicks in, voltage should be around 13.5v.
I had my original battery just replaced about a month ago. For 9 years, 120,000km, it was great.
I had my original battery just replaced about a month ago. For 9 years, 120,000km, it was great.
Member
Joined: Jan 2015
Posts: 115
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2007 civic Si 2004 Acura TL 2013 MB C350
static battery voltage for a fully charged battery is 12.5 volts with the engine off.....
if you load test the battery and voltage drops below 9.6 change it... no if and's or butts about it.... even if its showing fully charged before you load tested it.....
and while the car is running battery voltage should be 13.5 to 14.5 range..... at the battery or alternator.......
take into consideration with cold temperatures it will drop a few but thats when the CCA's (cold cranking amps jump in play)
hope this helps!!
if you load test the battery and voltage drops below 9.6 change it... no if and's or butts about it.... even if its showing fully charged before you load tested it.....
and while the car is running battery voltage should be 13.5 to 14.5 range..... at the battery or alternator.......
take into consideration with cold temperatures it will drop a few but thats when the CCA's (cold cranking amps jump in play)
hope this helps!!
Super Member
Joined: Jan 2009
Posts: 929
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From: Silicon Valley, California
Factory ordered 2012 MB C350 w/Dynamic Handling Package
I'm in the same boat, except I use my hardwired radar detector for constant voltage readout and a battery tester to measure CCA.
Current CCA (5.5 year old battery) is 580 (stock is 800). Battery testers generally will fail a battery at around 20% loss. I plan to replace mine at 70% when it reaches 560, so hopefully around the same time the car reaches 100k miles (currently 90k).
Current CCA (5.5 year old battery) is 580 (stock is 800). Battery testers generally will fail a battery at around 20% loss. I plan to replace mine at 70% when it reaches 560, so hopefully around the same time the car reaches 100k miles (currently 90k).
Thread Starter
Senior Member
Joined: Feb 2011
Posts: 465
Likes: 16
C204
static battery voltage for a fully charged battery is 12.5 volts with the engine off.....
if you load test the battery and voltage drops below 9.6 change it... no if and's or butts about it.... even if its showing fully charged before you load tested it.....
and while the car is running battery voltage should be 13.5 to 14.5 range..... at the battery or alternator.......
take into consideration with cold temperatures it will drop a few but thats when the CCA's (cold cranking amps jump in play)
hope this helps!!
if you load test the battery and voltage drops below 9.6 change it... no if and's or butts about it.... even if its showing fully charged before you load tested it.....
and while the car is running battery voltage should be 13.5 to 14.5 range..... at the battery or alternator.......
take into consideration with cold temperatures it will drop a few but thats when the CCA's (cold cranking amps jump in play)
hope this helps!!
Member
Joined: Jan 2015
Posts: 115
Likes: 4
2007 civic Si 2004 Acura TL 2013 MB C350
so with that being said turn the headlights on and dome lights and radio for like 5 min.... turn everything off then test the battery again...
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Thread Starter
Senior Member
Joined: Feb 2011
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C204
I meant 10.6 immediately after the start of the engine. It goes to 13.5 - 14.5 immediately after that when the alternator kicks in.
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2007 civic Si 2004 Acura TL 2013 MB C350
Junior Member
Joined: Oct 2017
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From: Park City
2014 C300 4MATIC
Question for the forum: will the local dealer replace a battery under warranty if it fails the test? I am coming up on the 4 year mark this month, so warranty is about to expire, and my battery is getting tired (used on many short trips). Cold mornings have a more sluggish start. I used one of the newer conductance testers that measure the internal resistance of the battery and estimate its capacity. My oem 800A EN AGM battery reads at less than 60% state of health (about 470 cranking amps
) warm and after a full charge. Do you think the dealer will replace under warranty if their test confirms it is that low?
) warm and after a full charge. Do you think the dealer will replace under warranty if their test confirms it is that low?Last edited by holger; Dec 4, 2017 at 12:21 PM.
Super Member
Joined: Jan 2009
Posts: 929
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From: Silicon Valley, California
Factory ordered 2012 MB C350 w/Dynamic Handling Package
Question for the forum: will the local dealer replace a battery under warranty if it fails the test? I am coming up on the 4 year mark this month, so warranty is about to expire, and my battery is getting tired (used on many short trips). Cold mornings have a more sluggish start. I used one of the newer conductance testers that measure the internal resistance of the battery and estimate its capacity. My oem 800A EN AGM battery reads at less than 60% state of health (about 470 cranking amps) warm and after a full charge. Do you think the dealer will replace under warranty if their test confirms it is that low?
https://www.youtube.com/watch?v=Oi8sUE9XCgA
) warm and after a full charge. Do you think the dealer will replace under warranty if their test confirms it is that low?https://www.youtube.com/watch?v=Oi8sUE9XCgA
BUT...
With that said, thanks for confirming that it'll still start with 60%. I've been on the fence regarding my battery sitting at 73% (580). Now I can rest knowing I can push it to the next oil change (100k miles) before replacing it.
Junior Member
Joined: Jan 2018
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From: NYC
c63
Battery light came on yest command shut off volt was 11.7.. after restarting car command came back and volt was 14.0 up until i did a few pulls went down to 12.0-12.2 nothing shut off car ran great. Can this be battery or alternator going?
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From: Texas
2012 Mercedes Benz C250, 2009 Porsche Cayenne GTS, 2019 Toyota 4Runner, 2011 Nissan Cube Krom
