Flexvolt battery are compatible with Dewalt 60v and 20v tools, and can be charged by 60v or 20v Dewalt chargers

DeWalt battery can last around 3 years
If the temperature is too high or too low, the battery won't be completely charged. It is always best to pay attention to the location in which batteries are stored. If they are kept in appropriate conditions, they can last even more than 3 years.

Class 1 Construction: The DEWALT Tool is grounded but not double insulated. Class 2 Construction: The DEWALT Tool is double insulated. Class 3 Construction: The DEWALT Tool is grounded and double insulated.

The only difference is in the amp hour capacity verified by the slight weight difference. Now most people choose to upgrade their 12V 4ah battery to the 5ah version. But if you wanted to save a little cash, or the 4ah was all that was available you could replace a 12V 5Ah battery with the 4 amp hour one.

Does it hurt DEWALT batteries to leave them in the charger? No. The DEWALT chargers have a maintenance mode which allows batteries to remain in the charger, maintaining a fully charged pack until the user is ready to work.

The FLEXVOLT 20V/60V MAX* 9.0 Ah battery provides the highest capacity of any battery on the DEWALT cordless system. It changes voltage when going from 20V MAX* to 60V MAX* tools and is compatible with a variety of 20V MAX* tools and chargers. In 20V MAX* tools it will provide extended runtime.

The letters “Ah” or “AH”(“amp-hour” or “ampere-hour”) that you see on your battery essentially denote the charge capacity(dewalt battery). The number alongside the letters will tell you the total amount of current the battery will consistently deliver to your tool over the course of an hour

dewalt 20v battery
Another sign of a battery gone bad is that even after charging the battery overnight, it still doesn't hold a charge. Finally, if you notice your battery overheating, it could indicate a problem with the battery's charge holding potential or another defect.

Absolutely not - the 18 volt pack is NiCad and the 20 volt is lithium ion. The chargers are not interchangeable as they use different charging systems.

DEWALT offers cordless tools of varying features.  

DEWALT 20V MAX is the next line after 18V, introducing lithium-ion batteries. 

• Standard size 

• Brushed motor  

DEWALT 20V XR improved on the 20V MAX line by introducing brushless motors and high-capacity lithium-ion batteries.  

•  Enhanced components  

•  Compact 

•  Brushless motors  

DEWALT 20V ATOMIC are designed to be compact and powerful for a wide range of applications.  

• More compact size  

• Light-weight 

• Optimized for tight spaces, overhead work, and longer periods of use 

• Brushless motor 

Longer jobs may require a higher amp hour. The three main types of DEWALT lithium-ion batteries are DEWALT XR: extended runtime batteries that last longer than typical batteries of the same voltage.

DeWalt 20V Max Premium XR Lithium-ion battery packs come in 2.0 Ah (DCB203) and 5.0 Ah (DCB205) sizes. They provide up to 33% longer runtime than DeWalt's standard 20V Max battery packs. They're comparing to their current-gen 20V battery packs, mind you—not their older post-style or NiCad batteries

When pack shut-off occurs, it can be reset by placing the battery pack on the charger and leaving it until the continuous light signal is shown to indicate either a fully charged pack or a pack that has been reset.