ITS Expert Says
Makita's Twin 18v heavy duty cordless platform delivers more power and runtime without leaving the LXT 18v Lithium-ion family. It differs from Dewalt's 'FlexVolt' range because if doesn't require a completely different battery. All you need is 2x Makita 18v batteries (either 3.0, 4.0 or 5.0Ah) and there you have it 36 volts!
When different capacity batteries are used together (for example, 4.0Ah BL1840 and 3.0Ah BL1830, or fully charged BL1830 and 70% charged BL1830), the machine stops when the battery with less capacity is empty.