What Battery Size is 8020-164?
That Battery Council International (BCI) has come up with a less than obvious system for designating battery sizes. We say that, because a Group 34 is smaller than a Group 27, which is smaller than a Group 31, but all of them are much larger than a Group 51 battery. However, even though batteries can be identified by group size, many also have a part number. Depending on the retailer selling that battery, the part number can be the same as the group size, similar or completely different. In the case of the part number 8020-164, the part number is completely different and unrelated to the battery size- Group 35 REDTOP.
Someone writing down a part number may be in a hurry and only grabbed "8020-164" off the battery or maybe they took a picture and that was the only visible number. Whatever the case may be, if you're search for a battery numbered 8020-164, the battery you want is a Group 35 OPTIMA REDTOP battery and you can buy it factory-direct with free shipping.