Size matters. Larger batteries in cars & trucks, more lead plate surface, more acid, more volume.

Car & Truck batteries take longer to break down the chemicals because there is more volume.

If you put a car or truck sized battery in a motorcycle, it would last just as long.

Additionally, there is a vibration factor in some motorcycles, which can cause the battery to degrade faster.

Some of the smaller batteries in cars and trucks start to degrade after 3 years but most can last 5 years and sometimes longer.

If you test a new fully charged battery it will show close to or more than the listed CCA.

If you test that same battery over time, say every 6 months you will see the CCA reduce because the chemicals and lead in the battery degrade and the plates get shorter (flooded cell) and the matting gets plugged up along with less acid (dries up) in AGM batteries.

All good stuff for discussion.

NOTE:
The above information, while credible, is worth what you paid for it and should not be considered gospel.
Do due diligence, research and have a H-D Field Service Manual before working on your bike.
You will probably have many opinions and suggestions presented; make sure you research the person providing the helpful information as there are some who provide good information that is useful and some who speak out of other orifices with gibberish. You will figure out this quickly.

 

I just read on a battery distributor site (1) it's true bike agm's don't last as long as car & truck agm's, (2) the principle reason is the bike's charging alternator isn't as large and isn't sufficient at idle rpm to charge (don't shoot me if you disagree, just a messenger).

Makes as much sense as anything, hence guys plugging in agm's between rides if not riding daily. btw, this has also been my experience with my truck which has beaucoup electronics on it, with the fob seeker always sending out rfi search radiation. Some guys make shutoff switches to defeat these, i'm getting too on in years to dink around with all these added electronics. So I plug in the truck on a C-Tek 5.0 amp maintainer, one of the models approved by Odyssey.

So - if there were a LiFePo battery that had a clean reliability record, I might go with it. As for what I've looked at, I'm not seeing it. Not very often do you get a defective new AGM battery. I never have.

Yuasa GYZ20HL is a good AGM made in USA (probably East Penn) for less than MoCo by $20-$30, which isn't much, but it is almost identical 20L size which I need for softail. You guys might want to check their GYZ30HL for touring if you stay with AGM.

 

I don't think that is a totally accurate statement.

There are many batteries available for a Harley at many price points. There are a lot of people who believe just because these many makes/models are made by the same manufacturer, that they are all the same.... I often try to point out they are made at the vendor's required specs, not all the same.

I believe reports of 2-3 year old battery failures are based on battery quality, battery location (heat kills batteries), pattern of usage, and storage (smart tender, trickle charger, nothing)... all those factors will influence the life of a battery. I think a quality battery, stored on a smart tender, and not run down below 50% of full charge, will last even on a motorcycle.

Case in point:
I bought a Yuasa GYZ32HL AGM battery (high quality, 500CCA) for my 2016 Bagger w/ 124" crate engine in 2018.

That bike is in SOCal, but is parked in an insulated shop/garage next to my house. When parked, it is kept on a smart tender.

I was taking a 2 week trip in Sept 2023. I knew I was going to be in desert temps of over 100°. Because of that, and the battery's age (5 years), I decided to replace it with a new Yuasa, before the trip. It is always easier to replace a battery in the garage, than on the road.

I set that 5 yr old battery aside on my work bench. No core was needed as I bought it's replacement online.

After I got home from the trip, I bought a battery analyzer to check my wife's car battery. Lucky I did, her large AGM was at 35%, but was 9 years old.

For the heck of it, I checked that old Yuasa on my bench. That Yuasa was at 12.6v and showed at 86% of original capacity. Not bad for a 5 year AGM battery used in a motorcycle with a high HP, large displacement crate engine in SoCal for 5 years...

Through the years, on all my bikes where I used high quality AGM motorcycle batteries, I have gotten at least 4-5 years, a couple at 7 years. I dare not go over 7 years. All were changed before failure, and I never had one die on me while on the road...

 

Speedcell Legacy 7.5 - what the Baja racers use. Only 2.5 lbs. Made in the USA. Comes with quick connect hardware. I change mine out at 7 years just because. Go to the Superbike races and you'll see what most everyone runs. Buy factory direct. Be sure to get a good lithium charger like the one here.
The best your money can buy.

Battery - https://thespeedmerchant.net/product...40232396128465
Order direct from Speedcell - www.speedcell.com

Charger -

 

You should give it a shot! I really think you would be pleased

 

That's the plan, but only because you recommended it 😉

 

You will always want one after this, they crank so fast and light off in half the time.

 

I'd be interested in which battery analyzer you have. Listed in percent, kinda sounds like percent charge.

 

I think I'd put more money on the fact that the regulator is smarter in the car and knows how to float a battery after it's fully charged. The HD unit don't.. Over Charging drys the AGM out.. The current 3 phase alternators are pretty good..

Undercharging info was likely true of the older motorcycles..

Yuasa is not made by East been but their factories are right next to each other..

 

Topdon BT100. You enter the type, the CCA rating, and then it runs a test...

After the test it shows:
a green light, yellow light, or red light

"Health: " / % of CCA / actual CCA
"Charge: " / % of volts / actual volts
"Internal R = " mΩ

It's just a cheap handheld tester, but it seems to be fairly accurate...

When I tested the new 500CCA, Yuasa GYZ32HL AGM. I recorded the test results in my maintenance log: Health = 100% 504CCA / Charge = 100% 13.0 volts / Internal R = 4.91mΩ