Batteries are strange items. Lot of things affect their longevity. If you ever run one down completely and recharge it, It will have a way shorter life expectancy. Heat is also bad on them. Many vehicles these days have the battery enclosed inside a box and force fed with ram air to help keep it cooler. My 05 Colorado has the OEM battery. My motorhome has 3 batteries all around 11 years. Out two blazers batteries usually give up around 6 or 7 years. We have also had 3 Honda Fits and never replaced the battery. We got around 5 years and 100K on our 09 Fit before my daughter totaled it. We got about the same on an 11 Fit before she totaled that one too. She is now driving a 16 FIT with a little over 30K. No battery problems yet.

So it is all in how you treat them and what kind of environment they live in. Keeping them on a maintainer when they are not used for a long time helps the longevity.

I did not give you an answer I would expect at least 5 or or 6 years minimum if you treat them well. You can get longer if you treat them VERY well.

 

Depends on the weather. I'd say it would have a shorter lifespan in either real cold or real hot weather.

 

I know this is an old post but I have a first gen fit with similar symptoms (though not as dramatic poor acceleration. Car would struggle to get up to speed and wouldn’t go above 70 mph). Turns out I had a failed catalytic converter that was caused by a failed o2 sensor that I ran on for some time (my fault).