Just starting to notice it getting a bit sluggish. Bike is a Jan2016 build, original battery still in it, 45,000km. Not a bad innings. Second set of OEM tyres now at 25,000km and looking pretty good still.

After 5-6 years I usually replace the battery
But our bikes were built 2014-15 so how can you have a Jan2016 build?

Japan is in a different time zone.

I read that they kept making them up until August 2016 - anyways mine def says 01/16 on the plate. It's the difference between "model year" and "build year" I guess.

you typically get three years "good" out of a motorcycle battery, since you are entering into the fourth year... yeah it's on borrowed time

With an original battery on a 2014, I've been shopping to replace it before my next out of state trip, and found you can get 2 business day delivery and pay a LOT less for the same batteries at WalMart. Look for a battery in format 20HL-BS 18 AH 310 CCA AGM (absorbed glass mat)
key dimensions are (H) 6.1" x (L) 6.89" (W) 3.43"

Here's one made in the USA (Chrome is made in Indianna and offers an 18 month warranty, ignore all the Harley stuff) $59.80 https://www.walmart.com/ip/YTX20HL-B...2004/196687637

The best advice I can give you is stick with Yuasa or Deka batteries. They are a bit more expensive, but you get what you pay for.

I think I posted this info a few years ago, but I spoke with the owner of a well-run battery business in town about Yuasa batteries. I used to have a landscaping company before retirement and have bought many batteries of all types from him. He said that he was a big fan of Yuasa, but only as "originally installed factory equipment". He said that he used to represent their brand, but found that replacement Yuasas that he could get from his suppliers never had the same battery life as the "orig.-install" ones. He said he even asked a Yuasa representative at a "Battery Business Convention" about the issue, but never got a satisfactory answer. He won't carry them now. WWIW