Sealed Lead Acid batteries (SLA), are the standard batteries that come with your kit. SLA batteries have been around for a long time. Some of their advantages are: they're reliable, easy to charge, and inexpensive. Disadvantages are: they're heavy, bulky, and they are very unforgiving when they are not charged back up immediately after use.

Your BD36 or BL36 kit will come with three 12 volt, 7 amp/hr batteries connected in series to equal 36 volts, or you can upgrade your kit to the extended range battery pack (3 - 12volt, 12 amp/hr batteries connected in series) for another $30.