The battery is the most important component for a battery-operated unit. Please be assured we price our batteries with the cost of material, manufacturing, and current market pricing in mind. 
Batteries are the costliest items to manufacture and ship in any kit. Full kits including a tool, battery, and charger are priced affordably so that consumers can begin building that line of tools and move forward purchasing tool-only units. When you purchase batteries on their own, it is more notable the cost that they carry.

60V/80V: To remove the battery, push and hold the battery release button. Then, pull the battery pack straight out. In some cases, if the springs underneath have gotten locked down you might have to give a small push to the top of the battery to re-engage them to help the battery pop up. The battery pack fits securely into the product to prevent accidental dislodging while in use; it may require a strong pull to remove. Before use, be sure that the rails on the battery and product are free of debris that could cause the battery to get stuck.
24V/40V: To remove the battery, press the latch button on the battery pack down and hold. Pull the battery pack out of the handle. The battery pack fits securely into the product to prevent accidental dislodging while in use; it may require a strong pull to remove. Before use, be sure that the rails on the battery and product are free of debris that could cause the battery to get stuck.

There are a few exceptions

• Our 80V 20” snow thrower models 2600402 / 2605202 / 2601302 manufactured prior to September of 2017 can only use 2.0Ah or 2.5Ah battery models.
• Our 60V 8.0Ah battery model 2957102 cannot be used in the following tools: any 60V 12" Snow Shovel, any 60V 22" Snow Blower, any 60V Tiller/Cultivator & any 60V Lawn Mower.

Yes, they do. Each product line has designated charger models that can charge all batteries in that voltage platform, despite Ah rating.