got a 21 Inch 56-Volt Lithium-Ion Cordless Self Propelled Lawn Mower. Came with a 7.5 ah battery. Can a lower Ah batteries be used (2,4,5 ah etc.) be used? same size?, Just want one to ad about 1/2 hr run time if needed. $350 is a lot for an additional battery (smaller ah is cheaper)
They can. I accidentally used a 2.5 ah battery in my 21SP. It didn't last very long with between the mowing and SP, but it did work just fine while it ran. I'm not sure how charged the 2.5 was when I used it, but I only got about 10-15 minutes out of it.
All ego batteries work in all ego tools and chargers - fully interchangable. Timothy is correct - you will only get 10-15 minutes from a 2.5 in a mower. Best deal is to buy a kit that includes a tool and a battery. How does a new blower or string trimmer sound. How about a snow blower with 2 batteries.