Help with Siglent SDL1xxx Electronic Load New DCR Mode - Page 1
Forum section: electronics / testgear

author: mbarszcz
author_rank: Contributor
timestamp: January 20, 2025, 04:07:50 am
content: Today I checked for a firmware update on my Siglent SDL1020X-E and saw that there was an update from Siglent that added a "DCR Mode". After fighting with different USB drives for an hour until I found one that the electronic load liked, I finally got the new firmware installed.Despite reading the terrible instructions, I still can't figure out how to use it or how it is supposed to work. The manual can be found here:https://tm-co.co.jp/wp/wp-content/uploads/2022/10/SDL1000X_UserManual_E02A.pdfinstructions for DCR mode are on page 57.QuoteWhat values should I be using for all 4 of these to measure the internal resistance of an 18650 for example? It seems that they can be completely arbitrary. It seems something like 10 seconds at 1A and then 10 seconds at 2A might be reasonableNo matter what I put in for time 1 though, it only ever seems to last for 1 second. The total length of the test seems to be 1 second for time_1 and then however long time_2 is set for. Maybe I just don't understand what the electronic load is doing.Anyone else have an SDL1020X-E that has used this feature?

author: TheDefpom
author_rank: Frequent Contributor
timestamp: January 20, 2025, 07:27:49 am
content: DCR doesn’t stand for DC Resitance, it stands for DisCharge Rate.The battery mode is used to discharge a battery using a specified current so that the battery capacity can be determined.EDIT: This is wrong, the update added a new feature back in 2023 which I had not noticed.

author: mbarszcz
author_rank: Contributor
timestamp: January 20, 2025, 08:05:24 am
content: I'm not so sure that's correct. This was added as a new feature and the unit could always measure the capacity of the battery in constant current, constant power, or constant resistance mode. Plus in DCR mode it has an Ohms readout.

author: tautech
author_rank: Super Contributor
timestamp: January 20, 2025, 08:40:55 am
content: https://www.youtube.com/shorts/1RuZ9lI0fHI?feature=share

author: mbarszcz
author_rank: Contributor
timestamp: January 20, 2025, 08:54:08 am
content: Quote from: tautech on January 20, 2025, 08:40:55 amThat's the constant current battery discharge mode not DCR, you can see it in the bottom left.

author: Tjuurko
author_rank: Regular Contributor
timestamp: January 20, 2025, 03:39:15 pm
content: T1 is always equal to 1s.Internal resistance is calculated using the classic formula: R=-(U2-U1)/(I2-I1).The higher "I2-I1", the more accurate the measurements. It is important not to exceed the maximum current of the measured device.Time T2 can be selected greater than 800 ms (measurement with any averaging is guaranteed).

author: TheDefpom
author_rank: Frequent Contributor
timestamp: January 20, 2025, 09:00:16 pm
content: Well well, I looked at my unit today and indeed DCR is to calculate an approximate DC resistance..It is buggy though, as selecting 5 seconds for both results in a 6 second test time... as mentioned T1 is always 1 second.I did a test on a 18V Lithium pack I am repairing at the moment and it gave me 312mOhm... my proper I.R. tester gave 88mOhm (this is including the cable connecting to the battery pack).

author: mbarszcz
author_rank: Contributor
timestamp: January 21, 2025, 01:34:05 am
content: Looks like it's just a load of rubbish then I guess.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: January 21, 2025, 02:37:31 am
content: I don’t use external sensing so that might improve the accuracy, also as mentioned, having a larger difference in test currents would also improve accuracy, I might dig into this in more detail later if I get time.I think in reality though if you want to test internal resistance, just buying a dedicated meter for it would be a good idea, even the cheap ones such as the one by FNIRSI work pretty well for that task, I own a few including a HP and they all are in the ballpark with each other.