Hello, Beyza.
I combined your posts into one thread since they are related.
There is a datasheet for the 99:1 Metal Gearmotor 25Dx69L mm HP 12V with 48 CPR Encoder available on the product page under the Resources tab. That datasheet has information for all of our 25D gearmotors, and you can used the information there to derive the other values you are interested in.
The armature/terminal resistance (R) is the motor’s rated voltage divided by the stall current.
The motor constant (Km) is equal to the torque constant (Kt) divided by the square root of the armature resistance. You can determine the torque constant by finding the inverse slope of the current-versus-torque line from the motor’s performance curve in the datasheet.
If there are any other parameters you are interested in, I suggest reviewing this post which covers how to derive or approximate several other motor characteristics, though please keep in mind that post is discussing a different motor, so some of the links and information there will be applicable for your motor.
- Patrick