I have a 2002 Prius. The 12 volt Battery is dead. The dealer indicated that a replacement battery is $135.00 plus a $50.00 for a hold down bracket kit. The parts person indicate that Toyota has a bulletin about the original OEM battery discharging on owners with short trip driving habits. The new battery is bigger and offer more storage capacity. As expected, non of the local auto parts stores offer a replacement battery. I looked up replacements on the web and came across this site: http://www.elearnaid.com/12vobaforpr2.ht... which claims 200 successful replacements with a Mazda Miata Battery and home made upgrade kit. Can anyone shed some light on this claim? Have you used such substitute? Are there any concerns or negative impacts on the vehicle electrical system? Are there any other feasible alternative? Both the Prius and the Mazda Miata Batteries require an outside ventilation. Some interesting informaton I found on the Mazda Miata: http://www.miata.net/garage/battery.htmlhttp://www.batteryweb.com/miata.cfm Thanks, KM