9V Lithium its a Forbidden power source for oscilloscope current clamp probes

[Kiriakos GR]

I got triggered today by a note, this offered by Rohde & Schwarz.
At their 9V powered current clamp probe for oscilloscopes, there is an intense warning, you are going to lose your warranty if you do not use exclusively an 9V PP3 Alkaline.

The same warning this is repeated since 2009 and up to 2020, for their AC/DC Current Probe (User Manual).

Long story in sort, all 9V Lithium they have inside an charging controller circuit along of one DC/DC step up controller circuit.
This DC/DC step up controller circuit it is active all times, this produces a powerful electronic interference.

Especially at low current measurements, the last thing that you need, this is having a source of electronic interference, few centimeter away from the current sensor.
This is equal of sabotage.   

From the other hand, what it does seems as unreasonable to me, is the fact that Rohde & Schwarz, this does not have love for these 8.4V PP3 NiMH.

HZO50, RT-ZC03, TA-189 (all three identical) they have as Low BAT level (LED indicator) the limit of 7.4V
While the probe will actually power OFF by it self, when battery voltage this goes down to 5.102V

In practical terms, these probes they use 20 mA of current, when low battery warning this activates, you have still several hours of energy in storage.


In conclusion, the use of 9V Lithium within active oscilloscope probes (for voltage or current), this is forbidden in the world of electrical test and measurement.
An 9V PP3 Alkaline this might be preferable, if you expect max battery life of 25 hours.
An good quality 8.4V 280mAh PP3 NiMH, this can come close to 13 hours as minimum.

Relative topic ...   
9V battery selection tips: Multimeter - LCR - IR Thermometer - LAN Tester