You probably know that early Delco battery date codes followed the "year-month-plant" configuration.
Battery plants were built around the country to service various GM assembly plants nearby. Batteries were expensive to ship because of their weight so proximity was important.
According to the 1953 Delco battery catalog a 1953 battery date code would be something like this:
"3HT" or "3LX"
3 is the year 1953
The letter A through M is January through December. The letter I was not used. J was September
T is the Muncie, IN plant and X is the New Brunswick, NJ plant
Since there were only two plants in 53 and Muncie was the closest to the Corvette assembly lines in Flint and Saint Louis it stands to reason that a 53-54-55 battery would have been made in Muncie, thus a "T" in the date code is what one expects.
Note the Anaheim battery plant was built in 1953 but too late to make any 6V batteries, except for probably aftermarket. Recall that 12V was the coming thing and some GM cars were already 12V in '53 (Cadillac and some Buicks). So Anaheim logically was destined to service GM plants in California (Fremont, Southgate and Van Nuys) plus the local aftermarket with 12V batteries. The plant code is "S".
In 1956 the Olathe, Kansas battery plant was built. Due to its close proximity to Saint Louis it became the go-to supplier for Corvette batteries. The plant code is "V".
So what would you see on a 1955 Corvette 12V? I would expect a "T" for Muncie. Probably a "T" for '56 as well as I don't know when production in the new Kansas plant actually started.
Next question: Where was the date code located on early batteries?
Since we don't seem to be able to find an original 6V battery we are guessing. (I actually had one from a junk yard but tossed it years ago, 1980's, when moving. The case was cracked due to freezing expansion of the water inside and I never was smart enough to take photos. Anyone with an original 6V battery or even a very early replacement please come forward!!)
Since we are guessing, knowing OEM 6V batteries had exposed lead connector straps, I'm of the belief the date code was stamped into a lead strap. I've also been told that by a person who says he has had original batteries and it makes sense to me. But this is an open question.
Per the 1955 Delco battery catalog, in 1955 the design of the 6V battery changed and the straps were no longer exposed like in prior years. (Take note, those few of you with 1955 6V Corvettes.) So at this point the only option for a date code was to brand it into the exposed plastic atop one of the cells (as shown in the current 53-55 TIMJG) or into the tar. I think melting a brand into the plastic makes more sense as the tar would stick to the branding tool and it would need cleaning between uses.
As a final note: The 53-55 TIMJG shows an example date code from a replacement 6V battery to be "J9C". I have no clue how to interpret that as it doesn't meet the "year-month-plant" convention Delco used on early batteries. However, I do know that as some point the date code convention changed.
The NCRS TIMJG for 63-64 says the convention was still "year-month-plant". But I do have a mid-year NOS battery with a code of "N7X". this appears to be some configuration for a 1967 battery made in New Brunswick. But there is no month "N". "M" is December. So do any of you know how to interpret J9C or N7X? What happened after '64??
Battery plants were built around the country to service various GM assembly plants nearby. Batteries were expensive to ship because of their weight so proximity was important.
According to the 1953 Delco battery catalog a 1953 battery date code would be something like this:
"3HT" or "3LX"
3 is the year 1953
The letter A through M is January through December. The letter I was not used. J was September
T is the Muncie, IN plant and X is the New Brunswick, NJ plant
Since there were only two plants in 53 and Muncie was the closest to the Corvette assembly lines in Flint and Saint Louis it stands to reason that a 53-54-55 battery would have been made in Muncie, thus a "T" in the date code is what one expects.
Note the Anaheim battery plant was built in 1953 but too late to make any 6V batteries, except for probably aftermarket. Recall that 12V was the coming thing and some GM cars were already 12V in '53 (Cadillac and some Buicks). So Anaheim logically was destined to service GM plants in California (Fremont, Southgate and Van Nuys) plus the local aftermarket with 12V batteries. The plant code is "S".
In 1956 the Olathe, Kansas battery plant was built. Due to its close proximity to Saint Louis it became the go-to supplier for Corvette batteries. The plant code is "V".
So what would you see on a 1955 Corvette 12V? I would expect a "T" for Muncie. Probably a "T" for '56 as well as I don't know when production in the new Kansas plant actually started.
Next question: Where was the date code located on early batteries?
Since we don't seem to be able to find an original 6V battery we are guessing. (I actually had one from a junk yard but tossed it years ago, 1980's, when moving. The case was cracked due to freezing expansion of the water inside and I never was smart enough to take photos. Anyone with an original 6V battery or even a very early replacement please come forward!!)
Since we are guessing, knowing OEM 6V batteries had exposed lead connector straps, I'm of the belief the date code was stamped into a lead strap. I've also been told that by a person who says he has had original batteries and it makes sense to me. But this is an open question.
Per the 1955 Delco battery catalog, in 1955 the design of the 6V battery changed and the straps were no longer exposed like in prior years. (Take note, those few of you with 1955 6V Corvettes.) So at this point the only option for a date code was to brand it into the exposed plastic atop one of the cells (as shown in the current 53-55 TIMJG) or into the tar. I think melting a brand into the plastic makes more sense as the tar would stick to the branding tool and it would need cleaning between uses.
As a final note: The 53-55 TIMJG shows an example date code from a replacement 6V battery to be "J9C". I have no clue how to interpret that as it doesn't meet the "year-month-plant" convention Delco used on early batteries. However, I do know that as some point the date code convention changed.
The NCRS TIMJG for 63-64 says the convention was still "year-month-plant". But I do have a mid-year NOS battery with a code of "N7X". this appears to be some configuration for a 1967 battery made in New Brunswick. But there is no month "N". "M" is December. So do any of you know how to interpret J9C or N7X? What happened after '64??