Different capacitance and ESR values - how to interpret - Page 1
Forum section: electronics / beginners

author: Takolito
author_rank: Newbie
timestamp: October 13, 2025, 07:31:26 am
content: Dear all,my first post here in the eevblog forum. I am a beginner trying to build a better understanding in electronics, mainly to fix electronic devices in our community. I would like to understand better how to best interpret the different capacitance and ESR values that different devices I use measure on electrolytic capacitors.I measured with a Fluke 117, a DER EE DE-5000 LCR meter with TL-21 probes and the DE-5000 with Kelvin clips from aliexpress. I calibrated the DE-5000 before use with each set of probes. I tested 3 new electrolytic capacitors with 4.7 uF, 47uF and 100uF. Here are the results:4.7uFFluke: 5.02 uFDE-5000 / TL-21: 4.79 uF / ESR 20.6DE-5000 / Kelvin clips: 4.28 uF / ESR 8.747uFFluke: 46.6 uFDE-5000 / TL-21: 36.81 uF / ESR 23DE-5000 / Kelvin clips: 30.28 uF / ESR 19.05100uFFluke: 91 uFDE-5000 / TL-21: 78.31 uF / ESR 1.9DE-5000 / Kelvin clips: 71.97 uF / ESR 0.9Capacitance seems to be reasonably close, at least within 20-30%. ESR however seems to vary a lot between the set-ups, is that normal? I would think that the DE-5000 / TL-21 should be the most reliable set-up, but wanted to check here if such variance is normal and what I could do about it.Many thanks!

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 13, 2025, 12:26:39 pm
content: What frequency are you doing the measurements/calibration at? When switching leads, do you recalibrate?The fact that using different leads changes the measured ESR so much is suspect. I'm skeptical as to whether either of those leads actually implements 4-wire measurement (or whether the DE-5000 supports 4-wire measurement at all). Though for small electrolytic capacitors I doubt a 4-wire measurement will be very different from a 2-wire measurement.

author: Takolito
author_rank: Newbie
timestamp: October 13, 2025, 01:39:46 pm
content: I measured at 100 Hz and recalibrated after changing the leads. As far as I know, the DE-5000 uses 4-wire measurement with the TL-21, but will check that again. As for the Aliexpress Kelvin clips, I would need to test. I think the DE-5000 defaulted to serial (as opposed to parallel) mode when measuring with either probe, could that make a difference?

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 13, 2025, 02:05:45 pm
content: Quote from: Takolito on October 13, 2025, 01:39:46 pmAfter doing the cal, try measuring some known impedances (open, short, 50ohm resistor, etc) to get an idea of if the calibration worked properly. If you have a known capacitor with very low ESR (ceramic or poly film) that would be worth checking too.QuoteYou mean it measured Cp/Rp instead of Cs/Rs? That certainly would make an enormous difference in the displayed values (as in, orders of magnitude for R).

author: mawyatt
author_rank: Super Contributor
timestamp: October 13, 2025, 02:23:46 pm
content: We can confirm the DER5000 employs true 4 wire Kelvin measurements, we have one and know as we've made some "Special Fixtures/Cables" which employ such. The TL-21 has 4 wires up to the small Gator Clips where the two Force and Sense wires on the High and Low Kelvin sides are soldered directly to the clip. This produces a surprisingly good result for most common DUTs.The 4mm "Banana" connections are unique and split in half for the Kelvin High and Low Force and Sense terminals. We've looked for affordable "Special" 4mm "Banana" plugs for this unique split "Banana" without success.The DER5000 utilizes the Auto-Balanced-Bridge technique with a special chip set from Crystal something (can't remember company) which helps keep this handheld affordable with good overall performance.Capacitance is relatively easy to measure accurately, ESR (RS) is a little more involved as this is a "parasitic parameter" within the ideal capacitor series simplistic model. You can see plots of capacitor Impedance Z and ESR here.https://www.eevblog.com/forum/beginners/do-i-misunderstand-esr-measurement-frequency-dependence-of-esr/msg6067267/#msg6067267BTW wrt to Kelvin Clip Zero Calibration, here's an interesting thread on such. You just can't clip the Kelvin Tips together, there's a proper way which produces significantly better results as shown in this thread. Please read thru the entire thread there's some good info in therehttps://www.eevblog.com/forum/testgear/kelvin-clip-zero-ohm-calibration/msg6030115/#msg6030115Best

author: Takolito
author_rank: Newbie
timestamp: October 13, 2025, 02:33:16 pm
content: Quote from: mtwieg on October 13, 2025, 02:05:45 pmThanks, I will test the calibration on the weekend. The DE-5000 defaulted to Cs/Rs, but I guess that would be fine for this level of capacitance, right?

author: Takolito
author_rank: Newbie
timestamp: October 13, 2025, 02:34:05 pm
content: Quote from: mawyatt on October 13, 2025, 02:23:46 pmThanks for the confirmation!

author: mawyatt
author_rank: Super Contributor
timestamp: October 13, 2025, 02:46:37 pm
content: You are welcome, we've added something wrt Kelvin Zero Calibration in the above post.BTW wrt to Kelvin Clip Zero Calibration, here's an interesting thread on such. You just can't clip the Kelvin Tips together, there's a proper way which produces significantly better results as shown in this thread. Please read thru the entire thread there's some good info in therehttps://www.eevblog.com/forum/testgear/kelvin-clip-zero-ohm-calibration/msg6030115/#msg6030115This technique doesn't cost anything, take longer or require specialized expense Kelvin Clips (works equally well with the cheap clips), but produces better Zero Calibrations.Best

author: gamalot
author_rank: Super Contributor
timestamp: October 13, 2025, 02:56:42 pm
content: I grabbed four aluminum electrolytic caps and did a quick check at 100Hz.

author: Takolito
author_rank: Newbie
timestamp: October 13, 2025, 03:53:10 pm
content: Quote from: mawyatt on October 13, 2025, 02:23:46 pmAwesome, thank you. I will check that I connect the probes for calibration as advised.

author: TimFox
author_rank: Super Contributor
timestamp: October 13, 2025, 04:54:51 pm
content: Quote from: Takolito on October 13, 2025, 02:33:16 pmIf you want to measure ESR, you must use Cs/Rs mode, since Rs is the ESR.In Cp/Rp mode for the same part, ifQ> 10, then roughly Cs = Cp and Rp =Q2x Rs

author: Takolito
author_rank: Newbie
timestamp: October 14, 2025, 05:29:26 am
content: Ok, thanks everyone for your feedback and advice. I will do another round of test measures on the weekend, making sure that:• DE-5000 is recalibrated after swapping probes as per approach as suggested by mawyatt above• DE-5000 is set to Cs/Rs mode• Frequency is 100 Hz for each measureWill report back. Thank you again!

author: gamalot
author_rank: Super Contributor
timestamp: October 14, 2025, 05:54:15 am
content: Quote from: gamalot on October 13, 2025, 02:56:42 pmI found my Fluke 117 and used it to measure these 4 caps. Their readings (in the order listed in the table) were 99.1 µF, 104.7 µF, 103.6 µF, and 94.8 µF.