Amazon currently has a battery promo deal running that is similar to what has been seen recently at Lowe's: "Buy a starter kit and get a Brushless RP bare tool free", which is a good deal to get especially for those who might not want to travel far to get to a brick-and-mortar big box store, but rather get it shipped to your door if you have Prime.
The deal currently includes battery kit CMCB204-2CK, which includes two 4ah batteries and a rapid charger. The following bare tools are eligible for the promo: 1/2 impact wrench CMCF921B (here), 1/4 impact driver CMC813B (here), cordless angle grinder 4-1/2-inch CMCG451B (here), cordless circular saw 7-1/4-inch CMCS551b (here), cordless multi-tool oscillating tool CMCE565B (here), cordless reciprocating saw 8-in CMCS351B (here).
The Cave has used all of these brushless tools and can certainly say this deal is a tremendous way to beef up your brushless V20 arsenal and have the right batteries too. 4ah batteries or better are typically more suitable at powering any of these tools that are included in this promo.
Get yourself to Amazon and check out the deal here!