March 17, 2010 based on information from the Prius forum. The Prius used the same 28800-31290 battery.

 

Thanks for that. Can you provide me with a link?

 

https://priuschat.com/threads/12v-ba...e-code.101829/

I also believe that other Panasonic small batteries are coded the same way.

 

Again, thanks for that, Kopavi. What you posted is perfectly consistent with rational reasoning, and it is indeed what I expected to discover, but wanted input outside of my own mind for confirmation.

Just to recap.

Panasonic D53 Battery Date Code interpretation is determined to be DD MM YY (for a 6 consecutive digit format).

For example (again, this is consistent with both my own battery and Andy's -Droid13- as mentioned in Post #s 7 & 8 above. In my own case...

First two digits are 17, and that cannot be the year since I have had this battery since before 2017. It also cannot be the month because there are only 12 months in a year. Therefore, the first two digits (17) represent the DD, or, Day of Month.

Last two digits are 10, and we've already ruled out that being the day of month, so it must be either the year or the month. If it were the month, that would make the second two digits the year, and this simply does not make any reasonable sense because that would mean that the battery from the factory was already 7 years old before ever being installed at the factory, and even more importantly, that would make the battery now 14 years old right now and it is highly unlikely that it would still be performing perfectly at that age point. Consequently, the last two digits must be the YY, or Year..

Second two digits therefore must be the MM, or Month.

Consequently, the 03 must be the month, and this is further confirmed by the conclusions above regarding the first and last two digit pairs.


Sooo... even if the conclusions regarding the last four digits are backwards, my battery is either almost 7 years old right now, or getting close to 14 years old, the former being the most likely and most reasonable conclusion. Either way, as far as I'm concerned, it has to go so I can ensure that my wife does not get stranded somewhere away from home or prevented from leaving home to get somewhere she needs to be. Now I'll just resume my battery selection process, buy it, install it, and shift my attention to other things.

Thank for all the input.

 

I have just purchased a RX450h recently and will be looking to take it to an automotive accessories store to get the battery load tested.
After doing lots of research on this forum, I've discovered that the battery is not a regular cranking battery but an AGM battery. I shall certainly be putting the battery charger onto this battery on a regular basis, to keep it in good working condition.

EDIT: When I received the new car, I found that the original Panasonic battery had already been replaced. In its place was a brand new aftermarket Start Stop lead calcium battery with bigger AH and CCA ratings to the Panasonic. After much consideration I've decided to leave the battery till it needs to be replaced. The vehicle had been in transport for about two weeks, so when I put the battery charger on this new battery, I was quite surprised to see that it took quite a few hours to get fully charged up.