Applent AT8612 DC load - a quick tear down

[thefamilyman]

Hello everyone

I'm new to the forum so i'll like to contribute a little something.
I purchased myself an electronic DC load for my testing purposes at work, I looked everywhere and looked at the Maynuo and BK units plus some others.
After some extensive self research and including reading on these forums I decided to venture a little into the unknown with the Applent AT8612.
I've noticed that their LCR meters are popular so i wanted to see how their DC load measured up.

My initial criteria was a 300W load, the Maynuo 300W units were a bit pricey so the AT8612 became even more tempting at US$360+shipping.

After a few months using it pretty much everyday I can say I am very happy with it.
Some thoughts:
I'm a sucker for LCD screens, you could sell me a poo if it had an LCD on it. The menu and screen is truly wonderful to use and looks even better than the photos portray.
Binding posts that I can use my standard (non shielded) 4mm banana plugs - a massive win! It still has binding posts too. This is a HUGE plus!
There was a UI bug where under certain conditions it wouldn't read the voltage correctly, but after contacting Applent directly the next day they emailed me a firmware update that fixed the problem.
4 wire sense is very useful and accurate.
Battery capacity test is quite useful.
Extremely quiet, even under full load the fans are very quiet but still move sufficient amounts of air.

It can test much of your standard tests like:
CC, CV, Constant Power, Constant Resistance, Transient CC CV CP CR, Battery testing, Sequence testing, Automatic testing.
150V, 30A, 300W.

As I said, it's only a quick tear down and brief review. I am more than happy to do a more extensive tear down and answer more detailed questions from my first hand experience.
The micro-controller is behind the transformer and I couldn't read it properly so in my more detailed tear down i'll take a closer look.

[Mr.B]

Welcome to the forum.
Thanks for your contribution.
It looks like quite a nice unit.
I have a Maynuo and really like it.

Now...
Off to start my new kickstarter... "LCD equipped poo"
I know I will have at least one backer. 

[thefamilyman]

Now...
Off to start my new kickstarter... "LCD equipped poo"
I know I will have at least one backer. 

[mcinque]

Hi, thank you for sharing the pics! 

[PedroDaGr8]

VERY interesting, while the interface is different, the load portion itself is very much related to the Mayuno M9812 but with upgraded parts.

Maynuo:


Yours:
https://www.eevblog.com/forum/testgear/applent-at8612-dc-load-a-quick-tear-down/?action=dlattach;attach=159539;image

Yours has upgraded vertical sandstone resistors instead of the flat laying large wattage resistors. Yours has a higher quality R-core transformer. In general, the fit and finish look much better on yours than the Maynuo but there is VERY clearly a strong relationship between the designs. Everything is in the same general locations, most of the same parts are there, etc. It looks like one is a revision of the other and that is it.

EDIT: Your LCD-POO comment made me actually laugh out loud.

[smgvbest]

I purchased one of these as well and have been very happy with it
Thanks for doing the quick tear down,  I had wanted to do it but it's very heavy and once I got in into place on my bench I've not wanted to move it.   

@thefamilyman
I'd love to get the firmware update if you have it?

[thefamilyman]

PM me your email and I'll send it to you

[tridentsx]

I have seen the same load under a different brand

http://www.ebay.com/itm/Programmable-Electronic-Load-300W-150V-30A-3-5TFTLCD-RS232-Battery-Test-AT8612-/301683686532?pt=LH_DefaultDomain_0&hash=item463dbfbc84

Ayone knows if its the exact same unit same quality ? It is cheaper and seems to use a different binding post.

[thefamilyman]

I have seen the same load under a different brand

http://www.ebay.com/itm/Programmable-Electronic-Load-300W-150V-30A-3-5TFTLCD-RS232-Battery-Test-AT8612-/301683686532?pt=LH_DefaultDomain_0&hash=item463dbfbc84

Ayone knows if its the exact same unit same quality ? It is cheaper and seems to use a different binding post.

its the exact same unit as mine.
Anbai is the chinese name for Applent, the same company.

the ebay link is the same seller as i bought mine from aliexpress, it's cheaper on Ali too.
http://www.aliexpress.com/item/Programmable-DC-Electronic-Load-300W-150V-30A-3-5-TFT-LCD-RS232-Handler-Battery-Test-Max/1970741643.html

[luciof]

Hi thefamilyman,

I also recently purchased the AT8612, and I'm quite pleased by its performance and build quality.
It's amazing how it can sustain loads in eccess of 850 watts without a hitch.

I also use a lot the BAT function, but there's a problem: when discharging a regular battery, as soon as its voltage drops below the threshold value the load shuts down and I can read the accumulated mAh's.
If I want to test a so called "smart" battery (the kind of which shuts itself off when discharged), the load shuts also off, but the mAh reading resets to 0.

This behavior can be reproduced connecting a power supply to the load: if I progressively lower the supply voltage below the set threshold, the load stops and mAh stay there.
If I instead shut off the power supply, the load stops BUT the mAh readings suddenly go to 0.

I tried to contact applent.com (anbai.cn) some days ago, but with no reply so far.

Maybe there's some chance the FW update they sent you also takes care of this issue (but I know it's too likely); would you mind send me a copy to lfilardi [at] alice [dot ] it?
My current FW is REV A2.7 under V6.0 OS version.

Another thing: is found that the front USB port readily recognizes USB sticks, but I could'n find a way to use it.
Anybody knows anything about it?

Thanks a lot!

    Lucio.

[tridentsx]

Does it have switchable mains ? It looks like transformer has two windings on primary. I can only find 220v model listed on ebay.

[luciof]

My (220V) unit has a 110/220 V rear switch, but it is not connected!
The diagram printed onto the transformer shows two separate 110 V windings, but they are connected in series without passing through the switch.

Anyway, to be sure, it would be better to choose the right voltage when ordering.
I got my unit from Aliexpress and saved quite a lot - even selecting the "expedite" FedEx shipping.

[thefamilyman]

Hi thefamilyman,

I also recently purchased the AT8612, and I'm quite pleased by its performance and build quality.
It's amazing how it can sustain loads in eccess of 850 watts without a hitch.

I also use a lot the BAT function, but there's a problem: when discharging a regular battery, as soon as its voltage drops below the threshold value the load shuts down and I can read the accumulated mAh's.
If I want to test a so called "smart" battery (the kind of which shuts itself off when discharged), the load shuts also off, but the mAh reading resets to 0.

This behavior can be reproduced connecting a power supply to the load: if I progressively lower the supply voltage below the set threshold, the load stops and mAh stay there.
If I instead shut off the power supply, the load stops BUT the mAh readings suddenly go to 0.

I tried to contact applent.com (anbai.cn) some days ago, but with no reply so far.

Maybe there's some chance the FW update they sent you also takes care of this issue (but I know it's too likely); would you mind send me a copy to lfilardi [at] alice [dot ] it?
My current FW is REV A2.7 under V6.0 OS version.

Another thing: is found that the front USB port readily recognizes USB sticks, but I could'n find a way to use it.
Anybody knows anything about it?

Thanks a lot!

    Lucio.

Hi

my firmware version is A2.2 and thats after a few firmware upgrades from small bugs that i've pointed out to Applent.
i've messaged Applent just now to see whats the difference between my FW and yours.

you can email directly to Applent, they are very helpful and fast to fix bugs (big surprise!) her mail is vera@applent.com

i'll attach my firmware and a pic of my current system info.

[crispy_tofu]

Thanks for the teardown! 

Now...
Off to start my new kickstarter... "LCD equipped poo"
I know I will have at least one backer. 

I'd buy the crap out of that. 

[luciof]

Thanks thefamilyman,

I sent a request to Applent/anbai through their messaging system, but didn't get a reply so far; I'll try to send an email to vera.

I'll also ask for the System Service password, which should allow me to mess with the calibration...
It's almost OK for now (just out by a couple of digits), but I'd like to be able to recalibrate the meters, just in case...

Regards,
    Lucio.

[AgiRigSig]

Hi,
this unit looks interresting.

Some short questions:

Is der any Software with it?
Has it an USB Interface on board or is a external Interface necessary?
Does anybody know where the Operator's Manual can be downloaded?

Thx

Torsten

[luciof]

Hi Torsten,

the unit comes without any software and with a printed manual, along with a pair of banana-alligator cables, a RS-232 cable, and a calibration/test sheet.
For what I know, no online manual is available.

On the anbai/applent website a dedicated software can be downloaded, but it's only in Chinese so far.

On the front panel there is an USB connector which explicitly recognizes FAT32 pendrives, but I found no way to use it, except to firmware updates.

Finally, on the rear there is a DB9F RS-232 connector.
It is a 2-wire only (RX, TX) RS232 interface responding to SCPI language (you can set the instrument parameters, send commands and read measured values; a cheap serial-USB interface should work fine).

I've not tried the more sophisticated functions yet, but in NORMAL and BATTERY modes it works wery well.
Although it's a 300W / 120V unit, I could make it work up to 300 V and over 500W for a few minutes without problems.

I also found some minor bugs, but they were promptly solved by firmware updates (usually within as day) emailing the issue to Vera (see previous messages).

Hope this helps.

    Lucio.

[AgiRigSig]

Hi Lucio,

thank You very much for sharing your experiences and for the fast reply.
I suspected something like this, regarding the Software und USB-Interface.
Is this a real RS232 Interface or has it TTL-Level? In this case a Levelshifter is required (as for other elctr. Loads from other Brands).

Kind regards

Torsten

[luciof]

Is this a real RS232 Interface or has it TTL-Level? In this case a Levelshifter is required (as for other elctr. Loads from other Brands).

It works at RS-232 levels thru a MAX3232 chip.

Regards,
    Lucio.

[AgiRigSig]

just to be shure (and not lost in translation :-)  , the RS232 Transceiver is onboard?

Kind Regards

Torsten

[luciof]

just to be shure (and not lost in translation :-)  , the RS232 Transceiver is onboard?

Yes, I did mean that the MAX3232 transceiver is on-board, so the AT8612 serial port can be directly connected to a standard RS-232 port.
Remember that it only uses 3 wires: GND, RX and TX - so there's no hardware handshaking.

    Lucio.

[AgiRigSig]

yes, I know. But is there no levelshifter on board and this Unit will be connected to a real RS232 Interface (+- 15V), the Unit will, or could be, damaged.
BTW..I have no PC with a real RS232 anymore, so I have to Interface from USB to (real) RS232 Level ....in case of I will buy the Applent...

Torsten

[luciof]

Well, maybe I didn't understand correctly...
I can confirm that the level shifter is included inside the AT8612 unit, so its serial port is made to be connected to an RS-232 port (not TTL levels).

To be exact, the AT8212 serial output typically swings between -5,4 and +5.4 V
The serial input can withstand up to +/- 25 V.

A serial to USB interface should work fine; in my experience, the best ones among cheap interfaces are those with FTDI (FT232 series) chips.

    Lucio.

[AgiRigSig]

Tank you very much Lucio, now all is clear...
I'm just looking at Anbais Website...

Torsten

[thefamilyman]

I've got a copy of the software in English that I will share later on

as promised:
https://dl.dropboxusercontent.com/u/1044245/EEVBlog/DCLoad/AT861x_ENsetup.zip