Beich CH9720CU Electronic Load Review - Page 1
Forum section: electronics / testgear

author: graybeard
author_rank: Frequent Contributor
timestamp: April 12, 2021, 12:12:29 am
content: I just posted part 1 of 3 of my Beich CH9720CU Electronic Load Review.Function & OperationHardware & Tear DownDiscussion, Recommendations, & ConclusionI cover specifications, demonstrate the accuracy of the measurements and settings, boot time, the ability to save data to a USB drive, show startup and transient waveforms, show noise in the load current, and demonstrate battery discharge measurements.In the video I conjecture that some noise I observe is due to a switching supply. Since I am working on the hardware and tear down video now I know the unit has a linear supply.I have been working on this video for almost a month 1-2 hours a day. I have done extensive testing, but only included the most pertinent results. It is however still 50 minutes long, but there was a lot of information to cover.I expect to have the next installmentHardware & Tear Downin 2-3 weeks, sooner if possible. I hope you enjoy it.Here are some useful links:A PDF of the slides is available hereManuals for this unit can be found hereThe listing at Alibaba where I purchased is hereCHANGZHOU BEICH Electronic Technology Co., Ltd English web pageChris Grossman

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: April 13, 2021, 03:13:30 am
content: Chris - thank you!This is an excellent review. Looks like it was a tonne of work to put together.I also have one of these loads. Overall, quite happy. I tend to use it for very specific customer testing, and have not fully explored all features. Your review is very helpful.

author: graybeard
author_rank: Frequent Contributor
timestamp: May 03, 2021, 04:12:25 pm
content: Here in Part 2 I take apart the unit, show details of the construction and design, show thermal images of the unit working, and detail both the good and problem aspects of the design.PDF charts for Part 2 are hereData sheets for the components used in the Beich load are here... Chris

author: bicycleguy
author_rank: Frequent Contributor
timestamp: April 13, 2022, 03:54:18 pm
content: Couldn't wait for part III and purchased a few weeks ago.FYIPositive changes:1. Capacitor is 400V.2. Version is upped.3. List length increased to 30, example auto solar panel test picNegative changes:1. Load Setup screen errors.The descriptions on the right side (3rd column) are messed up. CURR MULT is a repeat of bottom left and should be AUTO OFF. AUTO OFF should/be MAX CURR, MAX CURR s/b MAX VOLT, ect. Sent email to Beich, no reply.2. In System Setup/COMM MODE pressing enter key will show two blank menu selections. You can still select them though RS232C or USB-CDC. RS232C works, haven't tried USB.Same issues:. Acquisition Frequency in System Setup still requires down arrow to access.. sense connector fit same. Same bodge cap on fan connector although better done. Same interference on cap and heatsink. Four largest electrolytic caps are Chongx. Display is the same but it looks great and I don't consider this a Beich quality issue.. Fan turn-on at 25C is bothersome, at least it's variable speed.Really like it so far even with the blemishes. Wrote some SCPI to the back rs232 and worked no issues.

author: graybeard
author_rank: Frequent Contributor
timestamp: April 19, 2022, 03:15:21 pm
content: Quote from: bicycleguy on April 13, 2022, 03:54:18 pmI may do part three eventually. I put a lot of work into the first two parts, but I have had very few views.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: April 20, 2022, 09:40:36 am
content: Quote from: graybeard on April 19, 2022, 03:15:21 pmThanks to your videos, I also ordered this deviceI should have it soon

author: MegaVolt
author_rank: Frequent Contributor
timestamp: May 28, 2022, 12:17:09 pm
content: I received the device. First impressions: it works and works well for its price. But there are also disadvantages.1. New firmware is not available.2. Calibration password not available.3. Calibration instructions are not available.4. The calibration certificate matches the certificate found on the network up to the last character. Those calibration certificate is just a piece of paper.5. Judging by the values ​​in the certificate, it measures the current with an accuracy of 0.1% + 0.1FS, although the specification indicates 0.05% + 0.05%FS. And out of the box, it is close to the 0.1% border.6. voltage according to certificate 0.1%+0.015FS while according to specification 0.05%+0.03%FS. In real life, the error fits into 0.05%.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: June 06, 2022, 11:14:23 am
content: Some good news.I managed to get a program that calibrates the low current range.It is written in c# and is easy to parse. I am attaching the program and its source code. They check 3 points. 0.15A; 1A; 2.5A. The remaining points and ranges can be tried to pick up.

author: bicycleguy
author_rank: Frequent Contributor
timestamp: February 20, 2023, 07:00:47 pm
content: Good news everybodyToday I managed to get a software update from Beich for the CH9720CU.Now reports as V3.22.0509Previous attempts a year ago to sales@Beich.com.cn had failed. Tried again for the heck of it. This time got a reply from tech that asked what was wrong and I sent them screen shots of the menu issues noted in my previous post negatives 1 & 2. 1 Day later they asked for System info screen shot and 1 day later I received the update.Since they wanted the system info screen maybe the hardware and current firmware is important, don't know.Mine was:Hardware: V1.03Firmware: V3.21.0524If any interest I'll post here.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: February 21, 2023, 07:59:24 am
content: Quote from: bicycleguy on February 20, 2023, 07:00:47 pmThank you! This is great newsCan you share the firmware?Maybe this specialist will give you calibration instructions?

author: bicycleguy
author_rank: Frequent Contributor
timestamp: February 22, 2023, 02:22:18 am
content: Quote from: MegaVolt on February 21, 2023, 07:59:24 amI contacted Beich about sharing the firmware and got this:Code:Hi,You can post the file. The main chip has been replaced twice for lack of chips in the previous two years, sowe need to confirm the version information when sending you the upgrade software. However, differentchips and different models of software cannot be upgraded to each other. So if other people need toupgrade, they'd better consult us.Thank you for purchasing our instruments and your valuable suggestions. And best wishes with you.So the firmware is attached, use at your own risk, but better to contact Beich.Apparently this address is ok;tech@beichDOTcomDOTcn with the DOT changed to .