You can easily make your own.....with any discharge rate you desire.
The power resistors can be obtained from DigiKey....and aren't expensive at all.....
The number of resistors needed is dependent upon the discharge rate you want and the battery pack voltage you want to discharge...i.e. 2S, 4S, etc.
You just use Ohm's Law to determine the resistor values and to determine the number of resistors so that the discharge power can be equally distributed between the resistors....so that the resistors don't overheat and cause problems.
If you want to make your own discharge "unit", post the total pack voltage and your desired discharge rate, and I can show you what you need.....and how to connect them(the resistors will mostly be connected in parallel with each other).
The basic formula for two resistors connected in parallel is:
R(t) = R1 x R2 / (R1 + R2)
Using a bunch of 10W resistors is usually cheaper than buying a very high wattage resistor/resistors....just more soldering to connect them all together....
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