My Piaggio Typhoon 125 and Aprilia Sportcity 125 both came with the Yuasa YB9-B standard lead acid bath battery. I am sure this battery is used in several Piaggio scooters. These sort of batteries work but are very old school. They tend to vent causing corrosion and sometimes the vent hoses come loose and drip battery acid causing severe corrosion around the frame. Some reason they tend to cause a lot of corrosion around the battery terminals as well. You also must pull them out every so often and inspect the acid level and add distilled water on occasion. In most cases even with proper care they tend to fail after only few years. Some get lucky and get 4 or 5 years but that is seldom the norm. I have bought other bikes with this style of battery and usually live with them for while but at some point I will replace them with an AGM battery witch I am now thinking about doing on these scooters. AGM batteries hold a charge much better and with a little tendered care will usually last a long time. Also you don't have venting or corrosion issues. Frankly I am surprised these days that the EPA even allows these old school batteries. They can be a real mess! I like and have good luck with Yuasa batteries. Deka is pretty good as well in rare cases I can't find a Yuasa version. I thought for sure Yuasa would have a direct AGM replacment for the YB9-B but it looks like they actually don't. Every Yuasa I compare with is either to big or to small. Not sure how much room I have to play with in the battery box but its not much. The battery cover keeps the battery stable so not a lot of breathing room. Even my battery tender cable created some challenges! The only direct replacement I can find is the Scorpion YT9A. Some love out there for Scorpion batteries but a lot of hate as well. For those with Piaggio scooters that use the YB9-B battery did you find a direct AGM replacement?