36 V, 4.0 Ah Lithium-Ion battery. The AP 20 is an entry-level battery that powers some tools within the STIHL AP System. With an energy capacity of 144 Wh, the battery has an integrated LED charge indicator, clearly displaying as and when the battery needs charging. Ideal for lighter gardening and landscaping tasks, the AP 20 is suitable for domestic, semi-professional and professional users. Durable and IPX4 rated for all weather conditions, the AP 20 delivers long working times whilst offering a cost-effective way of powering entry level AP System tools. This battery has a cold start feature, which protects the cells by warming them up in a controlled way before delivering full power and allows them to work down to -20° Celsius. AP System batteries feature intelligent battery management system - this clever technology gives a constant level of power whether the battery is 100% charged or 1% charged. Compatible with the AL 101, AL 301, AL 301-4 and AL 501 charger unit.