That's because it's the OEM battery isn't it?
Aftermarkets won't last that long....
OEM batteries go in new motorcycles, aftermarket batteries go in old motorcycles. Buy an aftermarket battery and put it in a brand new motorcycle, how long will it last now?
Not as long as the OEM.
OK, I'll bite, show your work. What is the difference between an OEM battery and an aftermarket battery, what makes OEM last longer? All good batteries get sold to OEMs and all batteries with defects are sold to the public?
Battery manufactures have product manufacturing lines and they are not setup for one line to be OEM and another to be aftermarket. There is a lot of tooling, fixtures and highly refined processes that go into making batteries and to have a 'special recipe' for one customer and another variant for the aftermarket isn't practical. FWIW, the P/N of the OEM battery is the same as the aftermarket, if the batteries are different how do they keep the OEM inventory and aftermarket inventory sorted? FWIW II, OEMs try to manage cost and typically will not put top of the line components like tires, seats and suspensions on their products unless these components let the motorcycle compete in a niche performance area. Why would a battery be an exception to cost control over other items?
The difference is aftermarket batteries in the USA are made from ALL recycled materials (weaker)which don't last as long as batteries made in Japan which are not.
That's why "typically" (and like anything else there are exceptions to the rule) the OEM battery (made in Japan from all NEW materials) will greatly outlast a UAS aftermarket recycled battery.
I will point out that all lead (or any other element for that matter) has been around since the beginning of time and cannot be "new" or "old" ... Saying this is like saying that the billion year old lead just taken out of the ground is better than the billion and one year old lead taken from a used battery ...
There is no scientific basis to say that the recycled lead is "weaker"... There is no such thing as weaker lead ... It is just lead no matter where it comes from ...
Now, I cant comment on if the Yuasa GT battery comes off the same manufacturing line at the same time as the seemingly same battery that is a "YT" as opposed to a "GT" but, I am in agreement that it makes no sense (especially financial sense) to change the line and make crappier batteries only to slap a "Y" on them as opposed to a "G". I also don't know if the GT ones are made overseas and the YT's are made here ... But, they look identical, they seemingly perform exactly the same. They weigh the exact same amount and I have heard tales of praise as well as complaints about both of them.
They are lead acid based batteries. Sometimes you get a dud and sometimes you get a gem. In either case, it is tied to a defect of some sort or maybe a bad bump or bad maintenance or a colder winter. That's it ...