Author Topic: Part identification: 150W Constant Current Electronic Load 60V 10A (Read 23747 times)

sim · « **on:** January 15, 2017, 08:32:23 am »

Anybody know which IC might have "CAK4" written on the top? 6-pin (SOT-23-6, maybe?).

I grabbed a "150W Constant Current Electronic Load 60V 10A Battery Discharge Capacity Tester" from http://www.ebay.com/itm/182261413685 a few weeks ago... It seemed pretty decent on the first use, but when I was rewiring it for a second use, something sprung over while unscrewing the voltage sense wires, and poof, out goes the display.

Best guess, 25V was applied to sense V- (negative side of voltage sense) while it was applied across A+ and A- (the main load inputs). Thermal images now show the main 78L05, which everything seems to run from, getting hot (>120°C), and the only other hot thing on the board is U3, which is the 6-pin U3 package. There is an identical U4 next to it.

V- seems to run to U3's pin 6 and the board edge side of C5 and R9. With U3 removed, I can see that the damaged IC has pin 2 shorted to pin 5 while the one at U4 does not. Checking the pads, pin 5 seems to be VCC (5V), pin 2 seems to be ground, and pin 3 and 4 seem to route to the micro's pins 32 and 31, and so seem to be the outputs.

With U3 removed, it powers up and even works fine, except for the voltage sensing.

bktemp · « **Reply #1 on:** January 15, 2017, 08:52:04 am »

MCP3421: 18bit ADC
The layout looks like it has been done using an autoplacer + autorouter. The ground plane seems to be completely isolated from the actual circuit.

ass20 · « **Reply #2 on:** March 02, 2017, 08:13:04 am »

Hi
What is opamp used in this load?
any body make revrse schematic of this electronic load?

doctormord · « **Reply #3 on:** May 04, 2017, 10:51:50 am »

LM358.

I compiled some more infos here:

http://www.360customs.de/en/2017/01/150w-constant-current-load-60v-10a-battery-capacity-tester/

Scopetechniques · « **Reply #4 on:** June 05, 2017, 01:04:51 pm »

I picked up two of these for a project and the seller cannot understand anything I ask.
All I asked was what is the polarity of the 12VDC power input (NOT THE LOAD).
I also asked what is the current requirement on the 12VDC input.

I even translated the questions into Mandarin, they still have no idea what I'm asking and keep repeating "it is MAX 10A".

I know I can trace it out for the polarity and once that's done simply measure the current draw on the 12VDC P/S, but you would think that they could answer something so simple. Or at least silk screen the polarity on the board.

--Victor

Scopetechniques · « **Reply #5 on:** June 05, 2017, 02:14:48 pm »

Doctormord,

Even your instructions, do not show the polarity of the 12VDC!
I can't assume the units have reverse polarity protection and just try both ways.

--Victor

mc172 · « **Reply #6 on:** June 05, 2017, 03:41:14 pm »

The polarity is silk screened on the board.

Scopetechniques · « **Reply #7 on:** June 05, 2017, 05:54:29 pm »

Ha, thank you. Mine does not have that. Maybe it's a counterfeit

I have this one: http://www.ebay.com/itm/401315619647
As you can see it does not have the silkscreen you pointed out.

mc172 · « **Reply #8 on:** June 30, 2017, 07:24:09 pm »

I bought one of these for a laugh and received the version without the polarity diagram on the silkscreen. It doesn't always disconnect the load, instead it shorts whatever you've got it attached to. Not good.

The layout still looks like the crappy autorouter but it is quite different to the images posted in this thread by the OP. For instance, the track(s) around D1 in "img_5511" go around the top of the plated through hole, instead of below it.

serggio · « **Reply #9 on:** September 15, 2017, 02:22:12 pm »

Fortunately, I bought original one for about $30 at January this year. My DC load have no issue and extremely precise (I compared it with my Fluke 287).
I like how it work, primary I use it for check lead-acid batteries capacity.

I did two modification:
1. At display backlight I changed 100 ohm resistor to 1k for smooth backlight. Now backlight very "friendly" in darkness.
2. I also changed original fan with heatstick to new one - Cooler Master CP6-9GDSC-0L-GP. I keeped original thermal interface on new fan from stock. I have huge temperature decreasing - from 82 to 66 C at 125 W load!

DrZaius · « **Reply #10 on:** December 14, 2017, 01:33:15 pm »

Hello,

I have been using this electronic load for a year and it worked properly, but recently sensors went crazy and the load doesn't work at all.

It's attached a shematic, I have been doing some reverse engineering. Ceramic capacitors have not been measured yet.

Comparator LM393 (U6) seems only to detect a too low power supply voltaje. If input is lower than 10.30V you get the error 01.

In my case R7 was bad, with about 15 ohm when it is a 500mohm resistor. It seems that this caused the measurement problems. I tried to short circuit R7 but calibration process doesn't work fine...
I am going to look for a 0805 R500 resistor and try again.

zocra · « **Reply #11 on:** February 21, 2018, 07:53:49 pm »

Does anyone have a firmware for that device ?

I have one original and works perfectly, and another is disastrous and unusable

Thanks

zalex · « **Reply #12 on:** April 13, 2018, 08:01:08 pm »

I got the same load. It has just suddenly stopped working.

I found a blown fuse, shorted it with a thin wire, and have no voltage sensing at the moment.
Have tested U3 and it does not appear shorted.

Any ideas?

TA2AWX · « **Reply #13 on:** April 25, 2018, 01:09:49 pm »

Your schematics are great! You saved me from a ton of work.

Mine stopped sensing the voltage after I disconnected and reconnected it while it was running with 3A load.
I believe U3 ADC is dead... One question, it says "CAEE" on the chip, but the MCP3421's I find in AliExpress has "CAK4", "CADR", "CAYR", "CACP", "CAPC", etc markings, does this mean anything?

Thanks for a great job reverse engineering! All the best!

tsman · « **Reply #14 on:** April 26, 2018, 12:41:44 am »

Quote from: TA2AWX on April 25, 2018, 01:09:49 pm

One question, it says "CAEE" on the chip, but the MCP3421's I find in AliExpress has "CAK4", "CADR", "CAYR", "CACP", "CAPC", etc markings, does this mean anything?

The two digits/letters at the end are a batch code according to page 23 of the MCP3421 datasheet. They should be the same chip assuming they're authentic.

TA2AWX · « **Reply #15 on:** May 11, 2018, 09:53:04 pm »

A lot of 10 MCP3421's came from AliExpress today. Succesfuly changed the dead one, it is alive again.

A little calibration needed, easily done.

I have 9 more ADC's as spares.

I cannot thank enough to the ones that took the time to reverse engineer (DrZaius) and provide detailed instructions (doctormord) for this unit.

ALL THE BEST!

tocsa120ls · « **Reply #16 on:** August 25, 2018, 12:53:39 pm »

I bought one today, new SW version reported is 2.27.

My only 'big' PSU that can source high power is an older HP server supply, so we topped off at 12V/10A (120W)
The new version will not display voltage unless you connect all 4 leads.

Tried turning it off and on multiple times at 1A, 5A, 10A set loads, and not counting the groaning from the PSU, it worked, never glitched.

The magic button presses work, just a little different this time:
* Hold just the bottom right (SELECT) button while turning on the power: display says "Test IR mode / 0.000V 000m $\$\Omega\$$ " - no idea

* Hold both left (UP+DOWN) buttons, you get "Edition V2.27" and by pressing the SELECT button (bottom right) you get to the password screen. (As I don't have a password, didn't do any calibration checks.)

CPU seems a bit newer, a 90 cent STC 8A8K32S4A12
The big DPAK next to the power transistor is a MBRB20100CTG dual rectifier.

the orange trimmer besides the power jack is for setting the LCD contrast (from the factory it has the standard green backlit LCD, I replaced it with a negative blue one)
Between the transistor and the current shunt, a stern warning: "A heat sink must be installed to work"

Measured the differences between displayed current and actual current with my not-at-all-precision-but-decent Gossen multimeter, and got around .1% error - pretty nice for a €24 electronic load I think!

The serial terminal can be programmed to send data at 9600 38400 115200 baud, and the rate also can be set from once per second to once per minute. So the best resolution you can get is once per second. The terminal is one-way as far as I could tell.

elecdonia · « **Reply #17 on:** August 25, 2018, 06:29:27 pm »

I want to get this new version. Has anybody in USA been able to get this version yet?

I want to try the serial port . It is the white connector on right side. Older versions don’t have a serial port. Also this new version has big diode for reverse polarity protection. It is located to the left of the big MOSFET. Older versions don’t have it.

A month ago I bought a different version of this device on Ebay. It is older “fake” version that cannot be calibrated. It works but the current and voltage measurements are wrong by 10%

morgan_flint · « **Reply #18 on:** September 04, 2018, 06:32:53 pm »

Quote from: tocsa120ls on August 25, 2018, 12:53:39 pm

...Measured the differences between displayed current and actual current with my not-at-all-precision-but-decent Gossen multimeter, and got around .1% error - pretty nice for a €24 electronic load I think!...

Hi tocsa120ls,

Where did you buy it?

Searching on e-bay and aliexpress I could find these two sellers (searching "150W Electronic Load 60V 10A" and discarding all results of older versions from the photos), but they are a bit more expensive:

I also could see that there's a similar load with a graphic display and rotary encoder + 1 button, instead of 1602LCD and 4 buttons:

https://www.aliexpress.com/item/150W-Constant-Current-Electronic-Load-60V-10A-12V-Battery-Discharge-Capacity-Tester-Electrical-Instruments-Ammeter-Voltmeter/32906795921.html

Does anybody know this latter model? How does it compare with the 1602 one?

Thanks!

tocsa120ls · « **Reply #19 on:** September 07, 2018, 01:02:53 pm »

Quote

Where did you buy it?

The second link you have, "Good Idea store" on AExpress. For me it still shows €24 + free shipping.

elecdonia · « **Reply #20 on:** November 20, 2018, 09:16:33 pm »

Quote

I want to get this new version. Has anybody in USA been able to get this version yet?

I want to try the serial port . It is the white connector on right side. Older versions don’t have a serial port. Also this new version has big diode for reverse polarity protection. It is located to the left of the big MOSFET. Older versions don’t have it.

A month ago I bought a different version of this device on Ebay. It is older “fake” version that cannot be calibrated. It works but the current and voltage measurements are wrong by 10%

I obtained the new version of this device from the following ebay seller: csdf5963
The appearance is exactly identical to the photo posted by tocsa120ls
I have only had time to give it a basic test. So far it appears to work perfectly. The displayed current and voltage are very accurate.

SerЫй · « **Reply #21 on:** December 09, 2018, 12:08:20 am »

Quote from: tocsa120ls on August 25, 2018, 12:53:39 pm

The serial terminal can be programmed to send data at 9600 38400 115200 baud, and the rate also can be set from once per second to once per minute. So the best resolution you can get is once per second. The terminal is one-way as far as I could tell.

Please tell me which converter USB-to-UART you used? Maybe some settings?
Where did you find the setting for the period of sending data to the port (... once per second to once per minute)?

I used three different USB-to-Serial converters (CP2102, CH340G and PL2303), I checked the data line with a logic analyzer and an oscilloscope, there is always 5V on the data bus and no any data.

tocsa120ls · « **Reply #22 on:** December 10, 2018, 05:46:18 am »

I have a simple FT232RL USB-RS232 adapter. I can highly recommend it!

If you have no serial output, that means that menu option 7 is set to zero. This is the frequency of the update on the serial line, it has to be set to something OTHER than zero for the serial to work.

SerЫй · « **Reply #23 on:** December 10, 2018, 12:48:12 pm »

Great..
I have new genereation V2.31 and I have only five menu points.
What parameter setting in sixth point of menu?

P.S. Try connect battery in IR mode and press start. You must get internal resistance of your battery.

flatterband · « **Reply #24 on:** December 23, 2018, 09:41:45 pm »

Hello SerЫй,

i ordered my electronic load 11/2018 and got Version 2.31 like you. Like your version no menu found to configure x seconds data output. Both TxD and RxD show only 5V Pullup - no serial data out.

The seller advertised pc software in the auction for data evaluation. i requested a copy from him. The software installed labview and a application, but when run throws some error about missing vi files.

After getting back with the seller he did change the auction text that the software is probably not working.

So far with the latest software 2.31 there is no serial out working.


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Author Topic: Part identification: 150W Constant Current Electronic Load 60V 10A (Read 23747 times)

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