About a year ago I re-batteried my DTR650 fleet with factory fresh NEW batteries, 2000mAh each. $29 each on Amazon. Cell origin is Japan as these are aftermarket batteries. The DTR650 goes a LONG time on a charge with these batteries.
https://www.amazon.com/Replacement-Battery-Motorola-DTR410-DTR510/dp/B00PIYBRSW