I bought the string trimmer kit and I had the battery replaced do I register the battery by it self or as kit again cuz they just gave us the battery
As each item has its own part and serial number, I registered all items when I registered my purchases. So, for example, even though the mower came with a battery and charger not only did I register the mower but also the battery and charger. I'd suggest registering your new (replacement) battery. I've noticed, however, that even though I provided receipts all of my registrations say "no" on the receipt column in my account. So, who knows how well they actually keep track of the registrations.