Battery Voltage Discrepancies ??
Hello battery experts and fellow nerds :C I have noticed small voltage differences between the three Odyssey PC2150 batteries that make up my "bank". This is after resting with zero load for 24 ho...
Forum Discussion
Again .04 volt is nothing.
A customer bring me to or the batteries to me...
"Something's wrong. They seem weak"
I check the "at rest" voltage of each. Then they sit on their butt for 72 hours.
I go back and recheck. More than a .15 volt decline in one or any is a BAD sign.
I apply a PRECISION constant voltage regulated charge current to each battery. I start out at 14.00 volts. All the batteries should be equal as far as amperage accepted. Within 10% and that is being LIBERAL. For a group 29-31 a charge source potential MUST BE 70 amperes. The voltage MUST instantly rise to 14.00 and stay there. If your charger is too small or you cannot regulate it, then skip this test. Too bad, it's a good one.
The batteries stay connected to 14.00 volts at least 24 hours.
Then the charge voltage is adjusted up. To 14.50 volts. Again, it must instantly appear as 14.50 volts and then stay there. This is an 8-hour procedure.
A square wave test is performed. Looking for internal resistance too high, outside the norm.
Then a load test 50% of CCA for 15 seconds. I'm cruel here. .3 volt sag between battery test findings is death to the low battery. Check with the battery OEM as to how they want the CCA load test performed.
Two 12 volt 100 watt incandescent lamps, plus one 50 watt 12 volt lamp connected in parallel is close enough to 20 amperes discharge for atom bomb work.
I use a 12-volt kWh meter. I connect the apparatus, flip the switch and go away for exactly 240.0 minutes. I return, flip the load switch, read the kWh on the meter and proceed to the next battery.
Out of (?) hundreds of VR batteries I have tested this way, not one that has passed this test protocol has come back and bit me in the butt.
And yes, the kWh can be interpolated into information useful to an RV'er.
NO!
This test is not a routine stick a thermometer in the mouth and take blood pressure exam. It is reserved for batteries that have problems severe enough to warrant finding out if the problems are correctable.
The square wave, carbon pile load test, and kWh discharge tests are valid for use with flooded lead acid batteries as well. But 99% of the problems SCREAM OUT LOUD AND CLEAR during a hydrometer test (which comes first) eliminating the need to do the other stuff.
A customer bring me to or the batteries to me...
"Something's wrong. They seem weak"
I check the "at rest" voltage of each. Then they sit on their butt for 72 hours.
I go back and recheck. More than a .15 volt decline in one or any is a BAD sign.
I apply a PRECISION constant voltage regulated charge current to each battery. I start out at 14.00 volts. All the batteries should be equal as far as amperage accepted. Within 10% and that is being LIBERAL. For a group 29-31 a charge source potential MUST BE 70 amperes. The voltage MUST instantly rise to 14.00 and stay there. If your charger is too small or you cannot regulate it, then skip this test. Too bad, it's a good one.
The batteries stay connected to 14.00 volts at least 24 hours.
Then the charge voltage is adjusted up. To 14.50 volts. Again, it must instantly appear as 14.50 volts and then stay there. This is an 8-hour procedure.
A square wave test is performed. Looking for internal resistance too high, outside the norm.
Then a load test 50% of CCA for 15 seconds. I'm cruel here. .3 volt sag between battery test findings is death to the low battery. Check with the battery OEM as to how they want the CCA load test performed.
Two 12 volt 100 watt incandescent lamps, plus one 50 watt 12 volt lamp connected in parallel is close enough to 20 amperes discharge for atom bomb work.
I use a 12-volt kWh meter. I connect the apparatus, flip the switch and go away for exactly 240.0 minutes. I return, flip the load switch, read the kWh on the meter and proceed to the next battery.
Out of (?) hundreds of VR batteries I have tested this way, not one that has passed this test protocol has come back and bit me in the butt.
And yes, the kWh can be interpolated into information useful to an RV'er.
NO!
This test is not a routine stick a thermometer in the mouth and take blood pressure exam. It is reserved for batteries that have problems severe enough to warrant finding out if the problems are correctable.
The square wave, carbon pile load test, and kWh discharge tests are valid for use with flooded lead acid batteries as well. But 99% of the problems SCREAM OUT LOUD AND CLEAR during a hydrometer test (which comes first) eliminating the need to do the other stuff.
