They are being released in the UK at the start of August and were announced at a recent Dewalt event.
Here's what we've got in the Toolstop Blog
All UK model numbers will remain the same apart from the "L" becomes an "M" - for example a DCD985L2 combi drill with 3Ah batteries will be a DCD985M2 with 4ah batteries.
The weight is exactly the same. This has been achieved by the cell walls being slightly thinner (this takes weight out) enabling Dewalt to increase the amount of active materials in the cell (adding weight back in)
70 minute charge time from empty using the multi voltage battery charger which is also capable of charging Dewalts 10.8 and 14.4 volt batteries
The batteries now have a state of charge indicator so you'll never be caught out again by drained cells
The cells are currently manufactured by Sanyo
33% more runtime versus the 3ah batteries when used in the same tool - Simple maths 4 is 33% more than 3
1 year warranty