Beich CH9720CU Electronic Load Review

[graybeard]

I just posted part 1 of 3 of my Beich CH9720CU Electronic Load Review.

• Function & Operation
• Hardware & Tear Down
• Discussion, Recommendations, & Conclusion

I 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 installment Hardware & Tear Down in 2-3 weeks, sooner if possible.   I hope you enjoy it.

Here are some useful links:

A PDF of the slides is available here

Manuals for this unit can be found here

The listing at Alibaba where I purchased is here

CHANGZHOU BEICH Electronic Technology Co., Ltd English web page

Chris Grossman

[CDN_Torsten]

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.

[graybeard]

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 here

Data sheets for the components used in the Beich load are here

... Chris

[bicycleguy]

Couldn't wait for part III and purchased a few weeks ago.

FYI
Positive changes:
1.  Capacitor is 400V.
2.  Version is upped.


3.  List length increased to 30, example auto solar panel test pic


Negative 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.

[graybeard]

Couldn't wait for part III and purchased a few weeks ago.

I may do part three eventually.  I put a lot of work into the first two parts, but I have had very few views.

[MegaVolt]

I may do part three eventually.  I put a lot of work into the first two parts, but I have had very few views.

Thanks to your videos, I also ordered this device I should have it soon

[MegaVolt]

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%.

[MegaVolt]

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.

[bicycleguy]

Good news everybody
Today I managed to get a software update from Beich for the CH9720CU.

Now reports as V3.22.0509

Previous 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: V1.03
Firmware: V3.21.0524

If any interest I'll post here.

[MegaVolt]

If any interest I'll post here.

Thank you! This is great news Can you share the firmware?

Maybe this specialist will give you calibration instructions?

[bicycleguy]

Thank you! This is great news Can you share the firmware?

Maybe this specialist will give you calibration instructions?

I contacted Beich about sharing the firmware and got this:

Code: [Select]

Hi,
You can post the file. The main chip has been replaced twice for lack of chips in the previous two years, so
we need to confirm the version information when sending you the upgrade software. However, different
chips and different models of software cannot be upgraded to each other. So if other people need to
upgrade, 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 .