Just read this about batteries, there's a lot of rubbish been coming into the country from the far East, what appears to be happening is they are using reconstructed lead, that's to say that if you've wondered what happens to old batteries, they go to places like this and they break them down and reuse the lead cells after melting and remoulding them.
It seams to be OK for some applications of lead use but not for use in small motorcycle batteries. They will just about take 12-12.2 volts and that's Thier lot.
A couple of years back I had customer with an XS400 Yam, he'd got a brand new battery off the net, but couldn't use the leccie foot, so had to use the kicker instead. He wanted it sorting so brought it round, I checked the input to battery and was only getting about 12.2 volts at 4000 rpm, so I went round it doing all the checks .... Rec/reg generator wiring loom in general, put all new male/female (OEM) in the terminal blocks, but no luck
So removed the battery and put it on my intelligent battery charger, it told me to sod off I ain't haveing any of this, showed my customer and he was astounded!.
Had a look around the spares dept and found a used battery of roughly the same size, gave it a 30 minute charge fitted it to the bike kicked it over and checked the charge rate... 13.summut at the battery, confirming the brand new one he had brought was utter rubbish, equally one happy but unhappy customer, although he couldn't get his money back from the vendor, I did get him a yuasa one for just a quick more than what he'd paid for the other one. It's still working on now even able to use the leccie foot.