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Battery starting voltage

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Old 04-17-2014, 04:03 PM
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ant21b
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Default Battery starting voltage

What voltage should I read at the battery terminal when starting a 2010 coupe. I am reading 9.03 volts when starting some told me 9.6 volts or above was fine . I was also told 9 volts or above was fine. I did a load test on the battery and it tested good. Please advise.
Old 04-18-2014, 10:19 AM
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gbrtng
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Is the engine cranking at that voltage?
Old 04-18-2014, 02:22 PM
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Originally Posted by ant21b
What voltage should I read at the battery terminal when starting a 2010 coupe. I am reading 9.03 volts when starting some told me 9.6 volts or above was fine . I was also told 9 volts or above was fine. I did a load test on the battery and it tested good. Please advise.
By my car's fourth birthday it no longer seemed to start with the same gusto, so I hooked up the battery to a storage oscilloscope, turned the sweep way down, and fired up the car.

The scope revealed that the voltage was dropping into the mid-7s during cranking, and yet the car still started, every time.

I replaced the battery anyway, and with the new battery the car turned over a lot quicker. Incidentally, it also improved the smoothness of the clutch release, of all things, probably because the charging system wasn't loading down the engine as much.

I'd say you've got some time. Maybe install a new battery this winter, when the temperatures drop.

Last edited by torquetube; 04-18-2014 at 02:25 PM.
Old 04-18-2014, 07:32 PM
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irok
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Default should have

Originally Posted by ant21b
What voltage should I read at the battery terminal when starting a 2010 coupe. I am reading 9.03 volts when starting some told me 9.6 volts or above was fine . I was also told 9 volts or above was fine. I did a load test on the battery and it tested good. Please advise.
minimum 12.5 to 13.0 volts
Old 04-18-2014, 10:24 PM
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ant21b
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Originally Posted by irok
minimum 12.5 to 13.0 volts
No it should not read 12.5 to 13 when the starter is turning because it draws hundreds of amps from the battery. Thats the voltage when there is no load on the battery. If you do a load test with a battery tester you will see the voltage drop down.
Old 04-18-2014, 10:57 PM
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Default didnt say that

Originally Posted by ant21b
No it should not read 12.5 to 13 when the starter is turning because it draws hundreds of amps from the battery. Thats the voltage when there is no load on the battery. If you do a load test with a battery tester you will see the voltage drop down.
properly operating system not running or turning over should show 12.5 to 13.0 volts
Old 04-19-2014, 01:26 AM
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Originally Posted by irok
properly operating system not running or turning over should show 12.5 to 13.0 volts
Correct the battery voltage shows 12.61 volts with no load when I tested it. I wanted to know what the normal battery voltage is when the starter is turning its either above 9 volts or above 9.6 volts. If someone has the service manual it will state it in the manual.
Old 04-20-2014, 12:23 AM
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Originally Posted by ant21b
Correct the battery voltage shows 12.61 volts with no load when I tested it. I wanted to know what the normal battery voltage is when the starter is turning its either above 9 volts or above 9.6 volts. If someone has the service manual it will state it in the manual.
I do, and I don't think it specifies a minimum cranking voltage.
Old 04-20-2014, 07:34 AM
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timd38
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When I was managing the Chrysler OE battery business the number was 10.5 volts.

Remember that you can have good voltage, but lack amps. I have seen batteries with 13.25 volts but very low CCAs for various reasons such high specific gravity or paste shedding.

Also 12.61 id only about 80% state of charge. I retired in November and left all that kind of info the trash.

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