I'm using my 40v 4ah Ryobi battery to supply a 36v Mower. The mower starts and then stops right away. The connections and voltage works well. When I use 40v 2ah WORX
6Ah Lithium Battery Charger | RYOBI 36V MAX POWER RY36C60A
4Ah Battery & 1.7A Battery Charger Kit | RYOBI 36V MAX POWER RY36BK17B-140