I have an '09 Accord with only about 35,000k on it and I was wondering if I should replace the battery anytime soon. Hasn't given me any trouble but someone mentioned about every 4 years. wanted to post here to double check.

 

I would only change the battery if it stops working or tests bad using a battery tester. Most autoparts stores will do the battery test for free.

I'd keep a set of jumper cables in your car, because a battery can test good one day and die the next.

 

Thanks, the manual says there's a small windows on the battery that you can check the level but I don't know what to look for...

 

Testing the battery under load is a lot more reliable than the little window thing.

The little round window on top of the battery can tell you if the liquid level is down, but it won't tell you if the plates are getting covered in sulfates or falling apart. If your battery has removable caps that's even better, as you can see the level of the liquid in all 6 cells, but that's still not as good as a proper test of electrical performance.