Original Battery...
 

My 2010Fit Sport is still going with the original battery. I've had it tested a few months ago and still plenty off CCA, sorry I don't have the numbers in front of me. I live in an area where it gets pretty cold in winter so I'm thinking I should replace the battery before that. I plan to bring the car in for 2 new tires, and possibly have the brakes done. At last check they were getting pretty low. Is the battery replacement something I should do myself, or leave it to my trusted independent mechanic who I've been using for about 15 years now. I've looked at some YT videos on battery replacement, but I'm still hesitant. I also am wondering if I should look for a genuine Honda battery, or if not what folks recommend. I mention Honda battery because several of the YT videos showed that, while others did not.

Have it tested... If it's fine, keep it. My ranger when 10 yeays on the oem battery.
i also am a believer in OEM batteries for replacement. But every time one goes bad on me, I am no where.near a dealer, or it's a sunday and I cannot get ahold of an OEM. The ourl parts store special seem to still work, but have not tested one for 10 years yet.

8 years on the original Honda Fit battery is amazing. Did you buy it new? Are you sure it's the original battery? I have a 2016 and I'm already worrying about how much longer I might be able to go.

You live in an area that gets cold. If the battery is going to have issues, it will be when it's cold. Do you really want to be out in the cold changing it or do it when it's still nice out? A new battery is a $100-$150 item. Not a lot of money. ​​​​​​BTW: most discount auto part stores will install your battery for free. Another thing. I don't know where the Honda replacement battery is made but in my youth I worked at Johnson Controls battery division. We'd run different brand battery cases down the same line, putting the same guts in them.

I recently had to replace my battery (not the factory original). I had a Walmart Everstart Maxx 5 yr which made it about 3 1/2 yrs and then gradually died, replaced itn with the same thing. One of the better ones, manufactured by Johnson Controls. The group size is 151R, 340 CCA. Also grab a 2 pack of lead terminal shims, they look like thimbles. Slip over the post and work the cable clamp onto it. You'll be glad you did. Definitely need this to get a tight clamp on the + terminal. The factory cable clamp does NOT close tight enough without this and will come loose and you won't have a good connection. Not needed for the - terminal, fits fine and holds tight no problem as is (go figure....). Also don't forget one of the "ketchup packs" of anti-corrosion grease to ward off any future corrosion.