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Bought my 12 GS in 2014 and should have asked the dealer about the battery age...anyway, not having any issues , but wondering what voltage is considered "normal" for the battery ( not on a tender ) with the car sitting quietly for two days or so..... I put a meter on and got 12.4 If its the original battery it would be coming up on 5yrs. Any thoughts?
Voltage is fine but that doesn't tell you the condition of the battery. Go to a place like AutoZone and ask them to put a load tester on your battery. That'll give you the real scoop. If weak, replace now or you may be subject to all the weird gremlins which infest these cars due to poor batteries.
According to the SAE specs, the normal resting voltage of a new, fully charged automotive battery is 12.66 volts @ 70F. A battery showing 12.4 V has about 75% of a full charge.
On a car like a Corvette with a fairly high quiescent current demand, a battery tender should be used anytime the car is going to sit longer than a few days. This practice will maximize the life of the battery.
Garry
Last edited by Garry in AZ; Jan 3, 2017 at 10:11 AM.
According to the SAE specs, the normal resting voltage of a new, fully charged automotive battery is 12.66 volts @ 70F. A battery showing 12.4 V has about 75% of a full charge.
Maybe I'm missing something here, but how is the .26 difference equal to 25%?
Last edited by Corvette_Ed; Jan 3, 2017 at 12:10 PM.
All batteries have a manufacture date stamped in the case...depends on the battery where exactly and how to decode but you can google for whatever brand yours is and then you will know exactly how old it is.
All batteries have a manufacture date stamped in the case...depends on the battery where exactly and how to decode but you can google for whatever brand yours is and then you will know exactly how old it is.
I always thought the right way of testing the charge (without a load tester) was by checking the specific gravity of the electrolyte with a hydrometer.
The voltage doesn't necessarily tell you the depth of charge, which is what a load tester does.
I always thought the right way of testing the charge (without a load tester) was by checking the specific gravity of the electrolyte with a hydrometer.
The voltage doesn't necessarily tell you the depth of charge, which is what a load tester does.
But I'm no electrical expert.
Alot of todays batterys won't allow access to the battery fluid because they're sealed , so a hydrometer is useless.. A battery with a high reading of 12.4 volts is a battery on it's way out, probably a cell is dying.. OP will be looking for a new battery very soon......WW
Alot of todays batterys won't allow access to the battery fluid because they're sealed , so a hydrometer is useless.. A battery with a high reading of 12.4 volts is a battery on it's way out, probably a cell is dying.. OP will be looking for a new battery very soon......WW
True dat.
I still have a hydrometer around for my old tractor and boat, Harley is gone so don't need it for that anymore.
New stuff: For the past 30 years, I've only driven new trucks and sell them with 30-40k miles so I've never had to worry about batteries -- except on my '07 C6. I replaced it in '14 and TBH I don't know if it's sealed or not.
Voltage is fine but that doesn't tell you the condition of the battery. Go to a place like AutoZone and ask them to put a load tester on your battery. That'll give you the real scoop. If weak, replace now or you may be subject to all the weird gremlins which infest these cars due to poor batteries.
I always like to determine the replacement of components and not when something fails. I would hate to be at a restaurant at midnight and have a dead battery when trying to start the car. If the battery is over four years old I would put it on the replacement list within the next year.
Like Garry mentioned in his post, SAE specs place 12.4 volts at about 75%, with 12.66 volts being a full charge. I've seen open-circuit (nothing connected to the battery) voltages at 12.6 - 13.2 volts at the terminals on a good battery. If you haven't done so, use a battery tender if the car is going to sit several days or more. This will ensure your car will start (with a good battery, I might add) after sitting for a while and it will prolong the life of the battery.
Ultimately, the only way to do a truly relevant test of a battery is to test it against a load that is similar to what it experiences in real life. A group of AA batteries can provide 12.8 volts, but they can't come close to starting a car. A proper test of a car battery is to see how its' voltage holds up when hit with a couple of hundred amp load.
This chart is accurate as far as a state of charge on a battery. A battery that has not been messed with for a while. Not charged or drained recently. Charging puts a false "surface charge" number for a while, until the voltage settles for a while. How long? The longer the better.
Another battery question....
...WW
I always like to determine the replacement of components and not when something fails. I would hate to be at a restaurant at midnight and have a dead battery when trying to start the car. If the battery is over four years old I would put it on the replacement list within the next year.
