Abstract: An internal resistance testing device includes an excitation source and a battery pack, an adjustable resistance R, a sampling unit, and a control unit. The excitation source and the battery pack form a loop circuit. The adjustable resistance R may be located at the loop circuit formed by the excitation source and the battery pack. The sampling unit samples the voltage between two sides of the battery pack, the voltage between two sides of the adjustable resistance R, and the value of the adjustable resistance R. The control unit calculates internal resistance of the battery pack according to the signal value collected by the sampling unit. The internal resistances of different voltage-ranges the battery pack are determined by adjusting the value of the adjustable resistance R to cause the actual excitation voltage to be equal to the range voltage of the sampling unit.

Abstract: A novel and practical process for selectively producing a pyridobenzoxazine carboxylic acid hemihydrate (e.g., (S)-9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido-[1,2,3-de][1,4]benzoxazine-6-carboxylic acid hemihydrate) in high yield via crystallization from an organic solvent or a mixed organic solvent system containing a calculated amount of water released from sodium sulfate decahydrate under gradually heating.