dont get mixed up with brushless and XR - I thought the XR range of dewalt tools also meant the motor was brushless
however, my circular saw
DCS391N-XJ
https://www.dewalt.co.uk/product/dcs391n-xj/18v-xr-165mm-circular-saw-bare-unitis an 18V XR model - but its NOT Brushless
XR is the battery style (slideon) as opposed to the older XRP (plugin) battery style...
(even more confusing- the XR comes labelled as both 20v and 18v (it is identical in both battery styles 'nominal 18v' with the same number of cells in the lithium versions) and you can get 'brushless' in both styles...)
XR (marked as both 18v and 20v, newer style tools, lithiums only)
XRP (usually marked as 18v, plug-in, older style, available in Lithium, NiMH and even old Nicads (not interchangeable on the chargers,the tools use any, but each type has a different charger)
Lithium (note the ridges on the top, only fits lithium charger)
Older NIMH (although be careful, many aftermarket ones look like the NiMH, but are packed with lithiums!!!) Note no 'vertical ridges' at the top... Don't use the aftermarket on the NiMH charger- it will fit, but your battery pack won't last long...
18v Nicad (again, watch out for aftermarket ones that look like nicads, but are lithiums internally- these CAN'T be charged on the old Nicad charger!!!
Chargers are getting even more confusing, with some of the newer ones capable of charging any chemistry, but the older ones 'have' to be matched with their appropriate batteries....
(its a bit of a mess chargerwise, as DeWalt have been using the XRP style for decades, having gone through three major chemistry changes in battery packs (nicad, then NiMH, now lithiums- each with their own charging requirements... only recently have the new 'intelligent' chargers had the ability to adapt to whatever you plugged in- then they went and changed to the 'slideon' form factor- a move that lost them a lot of their trade customers, so much so they brought back the XRP for the 'tradies tools' and the XR is basically aimed at the home handyman level...