Two models side by side: measurements taken by the author in their reviews, and their conclusions. The better value in each row is highlighted.
In brief: Based on review measurements: Capacity: TPcell battery for Milwaukee M12 (6000 mAh vs. 4795); Resistance: TPcell battery for Milwaukee M12 (28 mΩ vs. 35); Temperature rise: TPcell battery for Milwaukee M12 (50 °C vs. 74).
Only in one review: Energy 88.43 Wh (BL1850); Test current 30 A (BL1850); Weight 400 g (TPcell battery for Milwaukee M12).
TPcell battery for Milwaukee M12: Capacity and cells are good, but the power contacts need improvement.
BL1850: A pack with genuine high-current cells delivered about 4,800 mAh; the author says it is worth buying.
Figures were taken from the review text and checked against the quoted passages. Measurement conditions differ between reviews, so read the reviews yourself before buying. Prices at the time of review.