Keithley 2450 - constant power battery discharge & distributor recommendations

[Sparky]

Hello friends!

I want to tackle Zinc-Air battery discharge testing and it seems the 2450 is the "go to" equipment for performing such tests, especially as you can then load the data as a battery model to the 2281S and reliably simulate battery conditions and check for weird behavior of your device as you approach the drop-out voltage.  I think that can be super helpful for testing low-power wireless devices that might start behaving unpredictable at critically low voltages.

I have read some Keithley app notes and watched YouTube videos and it looks as though the 2450/2460 only allow Constant Voltage (CV) and Constant Current (CC) discharge -- I didn't see any option for Constant Power (CP).  Is there any "work around" for attempting CP discharge with 2450?  Must one use a dedicated DC load to achieve constant power loads?

I have checked our EEVblog test equipment friends (TEquipment.NET, Saelig) for discounts but neither of them are distributors for Tektronix/Keithley.  Could anyone recommend a distributor in the US that is good for pricing of Keithley equipment?  It would be a great help!

Best wishes!
Sparky

[HighVoltage]

1.) You should be able to achieve constant power discharge through a script. It is almost limitless, what you can do with script programming in the 2450 and 2460 SMU.

2.) You might be able to get the best price or a significant discount at Keithley / Tektronix directly for a "demo" unit with full warranty and all accessories. At least, here in Germany, Keithley is offering these "demo" units for sale.

[Sparky]

1.) You should be able to achieve constant power discharge through a script. It is almost limitless, what you can do with script programming in the 2450 and 2460 SMU.

2.) You might be able to get the best price or a significant discount at Keithley / Tektronix directly for a "demo" unit with full warranty and all accessories. At least, here in Germany, Keithley is offering these "demo" units for sale.

Thanks @HighVoltage!  Using scripting is a great idea!  One can read back the voltage and then adjust the current for a specified power.  I wonder how much iteration would be needed?  Adjusting the current might cause a voltage change (particularly if the battery is new or approaching 100% discharge)...and one would need to adjust the current again based on updated voltage measurement, etc, etc.  Perhaps it wouldn't be too bad, especially during the time where the voltage of the cell is flat.

Thanks for idea of the demo unit!  That's great suggestion -- I will check it out!