General battery volt stats
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Elder User
Joined: Mar 2003
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From: Willamette Valley Oregon
General battery volt stats
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I'm looking for some general information on battery voltages.
I started with 12.54 volts and had a reading of 12.94 after an overnight charge. What is the acceptable voltage range of a fully charged battery in good condition?
What is the expected voltage output of a generator?
I'm looking for some general information on battery voltages.
I started with 12.54 volts and had a reading of 12.94 after an overnight charge. What is the acceptable voltage range of a fully charged battery in good condition?
What is the expected voltage output of a generator?
New User
Joined: Jan 2008
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General battery volt stats
Battery voltage can vary.
Check the specific density of each cell for a better idea of battery condition.
If I remember correctly 1270 is good number.
Voltages can go from 11.8v - 14.2 w/Alternators
Generators on the other hand will have a lower voltage
IICRC > 12.8-13.2 volts
You will have to do an accessories test with engine running at idle then at 1000rpm while turning on:
Heater
headlights
Wipers
either singlely or combinations of 2-3
Noting the voltage drop & increase from idle to revs.
Check the specific density of each cell for a better idea of battery condition.
If I remember correctly 1270 is good number.
Voltages can go from 11.8v - 14.2 w/Alternators
Generators on the other hand will have a lower voltage
IICRC > 12.8-13.2 volts
You will have to do an accessories test with engine running at idle then at 1000rpm while turning on:
Heater
headlights
Wipers
either singlely or combinations of 2-3
Noting the voltage drop & increase from idle to revs.
Moderator
Joined: Jan 2001
Posts: 56,966
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From: Virginia
General battery volt stats
You can't really test a battery unless you check each cell like Dennis said, or take your voltage readings under load. A real battery checker is a big metal looking meter with load resistors inside it. The meter gives you the reading while it puts the resistors across the battery.
Posting Guru
Joined: Aug 2002
Posts: 1,214
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From: Minneapolis, MN
General battery volt stats
For a quick battery test...
Needs charging... 12.2 volts.
Fully charged... 12.6 volts minimum to 12.8 with no surface charge.
When the battery just comes off the charger there will be a surface charge on the plates which should be removed to check the charge state with no load. That's where you got the 12.94 volts. If you let it set for a while the voltage will drop to the "normal" voltage.
To test capacity...
With headlights on for one minute on a fully charged battery with the engine off the voltage should not drop below 11.4v
If, when the headlights are on, the voltage drops below 11 to somewhere around 10.4 to 10.6 volts, there is a bad (shorted) cell.
Yes, a load tester is a better (faster) way to test a battery but the headlights put enough of a load on it to tell, if you know what to look for.
Just my 2¢
Greg
Needs charging... 12.2 volts.
Fully charged... 12.6 volts minimum to 12.8 with no surface charge.
When the battery just comes off the charger there will be a surface charge on the plates which should be removed to check the charge state with no load. That's where you got the 12.94 volts. If you let it set for a while the voltage will drop to the "normal" voltage.
To test capacity...
With headlights on for one minute on a fully charged battery with the engine off the voltage should not drop below 11.4v
If, when the headlights are on, the voltage drops below 11 to somewhere around 10.4 to 10.6 volts, there is a bad (shorted) cell.
Yes, a load tester is a better (faster) way to test a battery but the headlights put enough of a load on it to tell, if you know what to look for.
Just my 2¢
Greg
