Rigol DS1054Z and slow processes - Page 1
Forum section: electronics / testgear

author: jkprg
author_rank: Contributor
timestamp: October 12, 2017, 03:20:44 am
content: Hi!I'm about to buy my first scope. And it's gonna be DS1054Z probably. I just want to know if it's possible to measure/get characteristic of slow processes like charging and discharging batteries for instance. Automatically of course (kind of time-lapse during few hours). Is that possible?Thx

author: Dubbie
author_rank: Unknown
timestamp: October 12, 2017, 03:21:38 am
content: You could use a script to do it but it's kinda the wrong tool for the job. More appropriate would be a logging multimeter.Much better accuracy and resolution.

author: technogeeky
author_rank: Frequent Contributor
timestamp: October 12, 2017, 07:21:31 am
content: Quote from: jkprg on October 12, 2017, 03:20:44 amOther people answered the question "Is it a very good way to measure slow processes ... with a DS1054z?" The answer to that question is probably no, but it is certainly possible.The experimental setup:12V sealed lead acid battery (UPS battery)DPS5005 (buck) power supply25W constant current loadRigol 1054zThe settings:The load was set to draw 12.00 watts.CH1is watching the voltage of the battery, DC coupled, 2.00V/divCH2is watching the voltage of the battery, AC coupled, 50.0mV/div (to watch the noise fed back to the battery from the DPS5005)I am using theRigol Bildschirmkopiesoftware to take a screen captureevery 10 secondsover USBI discard 5/6 screen captures to make the displayed GIFIf, for some reason, you want to watch the GIF made from every data point (~ 15 MB),.You probably want to collect data rather than screen captures, but I made this to show that you it's certainly possible and it's already useful even in this sort of dreadful setup.For instance, we can see that as the battery drains more (and therefore the DC-DC converters V_input gets closer to its V_output, which was about 7 volts or so), its noise increases (or certainly changes shape).

author: bd139
author_rank: Super Contributor
timestamp: October 12, 2017, 07:29:11 am
content: The DS1054Z doesn't have great voltage resolution so this probably isn't the best tool for the job.I keep a Uni-T UT61E lying around for data logging. I've recently bought a GW Instek GDM-8341 for logging tasks but to be honest I haven't used it for that yet.

author: Fungus
author_rank: Super Contributor
timestamp: October 12, 2017, 08:00:56 am
content: Quote from: bd139 on October 12, 2017, 07:29:11 amNor do most 'scopes in this price range. They all use 8-bit ADCs.As noted by everybody else, oscilloscopes aren't really the right tool for this job. They're designed for fast signals.FWIW: The longest you can record with a DS1054Z is a couple of minutes.

author: Dubbie
author_rank: Unknown
timestamp: October 12, 2017, 08:32:01 am
content: Despite not being very precise technogeeky, that’s a cool little visual. I like how you showed the noise growing as the vbatt dropped.

author: technogeeky
author_rank: Frequent Contributor
timestamp: October 12, 2017, 08:37:17 am
content: Quote from: Dubbie on October 12, 2017, 08:32:01 amThanks!Yeah, when I set up the experiment I was telling myself: it's going to look really silly to just show an oscilloscope animation with a straight line moving, so what can I add to make it at least make a little sense as an experimental setup. I knew these units put some noise back onto their input so it was just the first thing that came to mind.Cheers!

author: oldway
author_rank: Super Contributor
timestamp: October 12, 2017, 08:50:52 am
content: Remember that to increase resolution and accuracy, you can use the differential method.For example, to plot the discharge curve down to 10V from a 12V battery, you can measure the voltage difference between the battery voltage and a stable and accurate 10V reference.

author: MrW0lf
author_rank: Frequent Contributor
timestamp: October 12, 2017, 09:07:05 am
content: Quote from: Fungus on October 12, 2017, 08:00:56 am8bit is not such a big issue when can average and do etc math trickery. I like math trickery. Yesterday measured phase of two 100MHz signals with 1MSa/s RTSAs for slow signals - here is current clamp warmup drift characterized over ~30min:

author: jkprg
author_rank: Contributor
timestamp: October 13, 2017, 03:46:31 pm
content: Wow. Excellent. Thank you guys for all the answers.

author: metrologist
author_rank: Super Contributor
timestamp: October 13, 2017, 04:32:39 pm
content: I think if you use segmented record, you can capture on the scope periodically over a very long duration. The manuals says something like a sweep every 10 seconds up to 60k frames, which would be 166 hours. I seem to remember is being around 16 hours, but probably depends on some other settings...