By larger, I mean both bigger in size and having more power. I chose an Everstart from Walmart. It cost $110 before sales tax, and it has 425 CCA, vs 370 CCA for the standard battery. It measures about 9" long. Below is how I installed it.

The first step was putting it on a charger for a couple f hours to get it fully charged. If you leave the car's battery disconnected for too long, the car will lose its memory. How long is safe? Good question. I've heard one hour.

Remove the negative clamp using a 10mm socket
Remove the positive clamp. This is a ridiculous design since it can't be easily moved out of the way. I'll have to look into that.
Loosen the 10mm nuts holding the hold-down bracket in place. Use a deep 10mm socket or an open-end wrench. Loosen them enough to wiggle them out of the holes in the frame below the battery.
Using a terminal tool or steel wool, clean the battery terminals and the inside of the clamps.
If the new battery doesn't have a handle, use a battery-lifting strap. There is another kind of lifter that clamps onto the sides of the battery, but there is very little room on the outside of the battery, and it might not fit.
In my 2015 Fit, the larger battery was a perfect drop-in fit. The annoying problem was the positive cable and clamp. I didn't have a battery lifter, so I was using both hands to lower the battery and move the big red thing out of the way.
To get the volts flowing, I connected the positive terminal first and then the negative, using a 10mm socket for each. I had a pair of those red and green felt "washers," so I put them over the battery terminals.

Now comes the fun part, attaching the hold-down bolts and bracket. This is how I did it.
I removed both nuts from the bolts and set the top bracket aside. After you do this, clean the threads so that you can easily spin the nut onto the rod later.
I first put the bolt nearest the engine through the hole in the piece under the battery. Then I slipped the bracket over the top of the bolt and put the nut on. If the nut is too loose, the rod will fall out of the hole. If the nut is too tight, you won't be able to get the other rod connected to the bracket. Fun!

It's not easy getting the other rod installation completed, but this is what worked for me.
With the nut removed from the rod, I fished it around until it went through the hole in the battery frame.
I used my left hand to hold the rod pulled up and pushed against the battery. With my other hand, I slipped the bracket over the top of the bolt, and then I screwed the nut onto it.
Be Careful! If the nut isn't screwed down enough when you let go with your left and, the bolt will slip out of the hole in the frame below the battery. Turn the nut as much as you can by hand and then use a 10mm wrench.

Tighten both hold-down nuts and put whatever kind of protective coating you prefer on the terminals.

This took me a half hour - installing the battery, not typing the directions.😁

 

The battery tray I have doesn't fit the 51r Battery.

I'm going to order the bigger Battery tray to fit the 51r Battery.

And a new battery cover for good measure.

I snapped one of the battery tie down rods due to rust. Another item on the order list.

So far the battery cranks up my Fit with lots of power over the stock 151r battery.

No more 151r batteries as long as I have my Fit.

 

Here's a link to my install with some pictures. I just cut the stock battery tray. Worked fine for the 5 years I had it installed and up to when my car was totalled

https://www.fitfreak.net/forums/3rd-...ml#post1446820

 

I saved over $60 compared with the cheapest 151R my son could find for his car.

 

this is what I recently purchased. $121.82 EverStart Plus Lead Acid Battery Group Size 51R 425 CCA SN JCH20098299315 2 year warranty. Walmart installed it without any issue. The reason I bought it was I left the internior dome light on overnight and the old battery died. I have never had any problems with batteries in the Fit.

 

I think something like that happened with my original battery, and I had to replace it after just four years.

 

I cut the battery tray and put in a 51R. Everything went fine. This was on a GE.

I noticed no improvement to cold starting, and I didn't like the way the 51R looked jammed in there, so I went back to the 151R.

Call me crazy.

 

Since it dropped right in without modifications, and since I saved $60 over the cheapest 151R, I'm satisfied.

 

No argument. If you want a bigger battery, it is, for most people, a drop-in solution.




Note: I'm speaking as a GE owner. Might be different for the 3rd Gen. I do not know.

 

From all indications the 51r Battery was most likely a Honda Factory choice of Battery for the 3rd Gen Fits. Some 3rd Gen Fits already have the larger 51r battery tray.

My 2015 does not.

I'll have to order the larger Honda battery tray to accommodate the 51r battery I have currently installed.

Most likely for cost cutting moves Honda changed to the smaller 151r battery.

The 51r Battery is a better choice for starting in cold weather areas.

 

Thanks for that. Interesting.

 

Lots I don''t understand about how Honda works but you'd think the savings would be in using the same battery and tray across the line. Not saying you're wrong. Just interested in Honda's rationale.

 

Exactly! Use the same parts as much as possible. That's why I can't understand why all American cars don't have Daytime Running Lights. They've been mandatory in Canada since 1990.

 

Pretty much every country has its own rules for certification. Honda probably has to provide an English/French owner's manual in Canadian-sold cars that they don't have to include in US-sold cars. I guess they figure where it saves them money to not provide it and where it does but not providing a 51-compatible tray and a cheaper battery just baffles me.

My previous car was German and the rules there require a rear fog light. If you took the taillamp housing of the DOT-approved version apart there was the wiring for that lamp, unmounted and without the bulb. Cheaper that way for them, I guess.

 

Cars in England have that rear fog light, too. We don't get much fog where I live.

 

3rd Gen USA rear tail lights look so elaborate. But only the lower portion of the rear tail lights are actually wired for lights.

The upper portion is just one big unlit reflector.

In other countries the 3rd Gen rear tail lights are totally fully lit.

 

Many years ago, I bought a Chrysler product without the rear window defroster. That was available as a kit for a reasonable price. All the wiring was there. I'm come across things like that in other cars. The company uses uses one wiring loom for all cars, cheaper and simpler.

Is the taillight construction totally different, then? Different lens?

 

For those interested in getting the Factory Honda 51r Battery Tray and Cover.

Battery Tray;
31521-T5A-000

Battery Cover;
31531-T5A-003

 

Our 2020 EX battery cozy/cover was already sized for the 51R. The battery dropped right into the sleeve like it was designed for it.

 

Like I posted.

The 51r battery was a Honda Factory Battery originally installed by Honda.

Which is why some Fits already have the 51r Battery tray installed.

Probably in a cost cutting move the 151r battery was chosen.