Speaking about batteries. I too called Yuasa and asked how long a dry battery's shelf life is, and he said no problem, wet it. He then proceeded to tell me about taking the competition's batteries and charge them a certain way. Nothing special, but they first let the acid soak for a least an hour. then fully charge the batteries. Place a load on them and run them down to about a volt and then recharge it. Done a third time and now it's ready for service.
He continued to tell me how to charge it. In other words, yes, you can throw a car amp charger at it, but be careful about it getting too hot. So basically I took the plunge and got 9 years out of another brand battery. The shelf life battery hardly had a charge on it and I let it sit till I sold it 6 years later. Still light right off when the new buyer came to see it.
My procedure was to buy the right battery charger. So if the battery is a 12N14a, you move the decimal point over one to the right, and you now need at least a 1.4a rated battery charger, charged for literally 14 hours. That's the formula. I then took both a high beam and a brake light bulb and let it slowly die out to 1 or 2v and recharged it; repeated 2 more times, and then put in the bike. Dielectric greased everything.
This time I just wet and charged. The triple charge always read 12.7-128v static. This one reads 12.4v static. I guess I learned my lesson.