It might be worthwhile to call a dealer parts department and see if they can help. The other possibility is tape measure. Go to a battery display with Height - width - length and position of posts.
Perhaps you can wedge a physically bigger battery in there w/some custom fitting. If you try a different group size, make sure the +/- posts are oriented correctly & on the correct side, and that the highest point of the battery isn’t so high that it will contact the hood when driving over a bump. Consumer Reports does an annual battery rating. Which vendor/model tests out best depends on the battery group size, so that’s a good resource.
Do you actually have a problem getting the car to crank and start on cold mornings? Or it this more theoretical? If you actually have a problem, folks living in really cold climates, like Wyoming & Montana near where I used to live, I noticed they often use some type of engine compartment heater overnight that they plug in to an electrical socket to solve that problem. That might be a better solution for you than trying to wrestle in a physically bigger battery. Square pegs don’t fit round holes.
Note: Smaller engines like in a Fit often don’t require as much battery power as cars w/ bigger engines; and it also depends on compression ratios, starter/flywheel gear ratio, & whether the starter motor is a direct drive or a gear reduction version. So you can’t really compare the CCA needs of one car vs another directly. Just saying, so you don’t end up on a wild goose chase there.
The best I’ve seen so far is Car Quest @ 370 cca. ( Car Quest Gold by Johnson Controls )
All my other sources are 340 ( Auto Zone, O’Reilly’s, AC Delco )
It is friends car and it is the original OEM battery. It is time for a new one and when I looked at it i was shocked to see such a low CCA for a car in New England. It is probably the smallest car battery I have ever seen.
I always look for a battery with a higher CCA than what the factory specs. It seems like it is a specialty battery being so small physically.
I Think the Car Quest at 370 CCA is a typo. I believe It is the same battery at Advance Auto Parts and that says 370 in the heading but the specs sheet says 340.
I read on one board that the group 121R will fit but it is taller and it will require a new hold down bracket. I will need to investigate this…Can anyone confirm?
Its a little car with a little engine…and it’s a Honda which all tend toward small batteries. Tell your friend to put synthetic oil in it if he’s concerned about it starting and it likely will never have a problem
Check on the Fit forums, it does look like a bigger one can fit with modifications. Whether you want to make them is up to you/your friend. But if you do, make absolutely sure the battery is secured, you don’t want it bouncing around the engine compartment.
I really doubt anyone here has done that modification.
340 CCA is plenty for a 1.5L engine, it has lasted 7 years without trouble, hasn’t it?
If there was a need for a larger battery Honda would have provided a larger battery tray for an optional battery. Replace the battery with a direct replacement and close the hood.
You can use a Group 51R battery (not 151R) with a slight modification. The 51R battery has much higher CCA.
There’s a plastic battery tray underneath the stock battery. The 51R battery is about an inch longer than the 151R, so you have to remove the plastic battery tray and remove the lip or side of it. The 51R battery will “butt” up against the air filter box… but other than that it fits perfectly.
My 83 colt had a Panasonic battery. The tray had a molded spacer that allowed a larger battery to be installed. At least 1-2" additional space. Cute little battery. I swear it was close to my riding mowers battery in size.
If its worked fine all this time, just get a good quality OEM style. I hear your concern since my lawn mower battery is 270, but still don’t go modifying anything on someone else’s car. Unintended consequences and no good deed goes unpunished and all that.
I live in Vermont and installed an engine block heater in my 2008 Fit. It makes a huge difference on those cold mornings. I agree the battery is small, but there is so much stuff working against it in the extreme cold. Cold starts in really cold weather are really bad for the engine anyway, so warming up the engine with the heater will likely extend its life AND without the need for a bigger battery.