I have being doing some work using a SuperCap, and during this work i discovered that when i turn off the channel connected to the SuperCap a discharge started. Doing some more experiments, it seems that all 3 channel has a constant current load at about 40 mA when turned off.
This can be tested by connecting channel 1 to either channel 2 or 3 (plus to plus, and minus to minus), turning up and down the voltage on channel 1 (and having channel 2/3 in off) I can see that channel 1 is drawing about 40mA no matter the voltage.
Is this behavior stated somewhere or is it common knowledge?
Maybe it can be something related to the fact that almost any lab PSUs shorts the output when a channel is turned off?
The current source on the output is used to reduce the transient response time to load changes, worst case scenario would be load change from zero to maximum current.
Shorting the output of a power supply is a bad idea, in your case it would mean that the super cap will blow up what ever is used to short the output.
OK, I had the the false assumption, that the off-switch actually was some sort of relay function disconnecting the output. The DP832 is rather new in my lab, in the past I had a traditional power supply, where the off function was pulling out the plug. It seems that I have to work that way again, at least when measuring discharge time of the SuperCap power supply I am building.
Shorting the output of a power supply is a bad idea
I want to say "discharged"
Look at my signature and you will understand that I'm not new to this facepalms
I seems quite a few of these units have this problem. I had one, sent it back and got a unit without the issue. If it's just a calibration issue, it seems Rigol would be much better off describing how to (re)calibrate the unit (if possible) rather than shipping the units back and forth. It seems crazy that they can't simply figure out these units draw current without load in the factory...seems obvious to me.