ARRAY electronic loads

[reagle]

It's a slow going since I am learning the language while at it. So far I can talk to the load and get and parse data it sends back. At this rate, check in a year
Though we can start a wish list of the features. For now this is all command line - start, run, maybe get log data type of a thing

[nctnico]

I wrote a command line discharge tool in C++ which also produces a CSV file you can import in Excel. I'll try to zip it and post it in a few days. It can compile on Linux and Windows.

Edit: attached source code. It is an Eclipse project and compiles for Linux. It can also be compiled for Windows but it may need some tweaking (defining WIN32). When compiling make sure wxserial/linux and wxserial/win32 are excluded from compilation. The files in these directories are pulled in by including them.

[saposoft]

I have a small utility to characterize batteries using an Array 3710A e- load .
It works much better than the provided software .
Have a try it's free
http://sites.google.com/site/elettronicaarduinoesperimenti/

[ted572]

I have a small utility to characterize batteries using an Array 3710A e- load .
It works much better than the provided software .
Have a try it's free
http://sites.google.com/site/elettronicaarduinoesperimenti/

I would very much appreciate it if this was also available to work in Windows XP and 7 for x32 & x64 hardware.
Thanks for any consideration of this.

[battery]

Im new to this forum but had a read through the electronic loads posts. Some great reports. Im looking at getting an E-Load to mainly test various battery types but mostly Lead Acid up to 250 Ah or so. Looking at either BK 8500 Maynuo M9712 or M9712C and also the Array 3721A loads. Im in AU Sydney area I can get the BK and Array locally BK8500 $1500 Array 3721A $1200 may be able to do better on the Array? A previous post mentioned the array software is a bit buggy. 

Any advice or suggestions would be appreciated

[VK5RC]

On 'fleabay'  the 3721 goes for about $900.
Regards Rob

[nctnico]

I got mine through Ebay as well. I can sum up the the software which comes with the dummy loads with two words: useless crap.

[HighVoltage]

I have a BK Precision 8500 and a Maynuo 9811
And I can highly recommend any one of those two instruments.
Somehow, I like the Maynuo a little more, because it has 2 lines and 4 numbers at the same time in the display.
So, watching voltage, current and power at the same time, is sometimes a little benefit
And the software on both systems works great.

For a lower end project, I needed a low cost solution and ended up with several 100 W power resistor, instead of a DC load.
Because I did not like the lower cost units at all.

[Circuitous]

I have a couple of Array loads, 3723A and 3710A.  I like that they can display 4 attributes at once (unlike the BK) but the PC software isn't great and it has a crappy TTL interface (not RS-232 or USB) that requires an adapter (you can make your own).

The backlit LCD on the 3723A is clear and bright, easy enough for me to read from 3 feet away. But, I still would prefer a VFD.

If I was starting over, I'd probably get the Maynuo.  I may pick up a M98xx later this year.

[MarkL]

I have a couple of Array loads, 3723A and 3710A.  I like that they can display 4 attributes at once (unlike the BK) but the PC software isn't great and it has a crappy TTL interface (not RS-232 or USB) that requires an adapter (you can make your own).

The 3723A has an isolated, true RS-232 inteface.  No adapter needed.

[saturation]

Its hard to believe my unit is over 1 year old now, an Array 3710a rebadged as a Tekpower brand.  I use it a lot and its saved me a lot of time, grief and burned fingers.

I've definitely put it through its paces, often burning at full 200W nearly a day, and the thing never gets hot.  The hardware is very well made for what it does and the LCD screen is accurate as displayed; I've checked it many times with DMMs as backup for V and A readouts.

The software is poor but functional.

Even if you buy direct from China via Taobao.com the Array 3710/1 is typically ~ half - 1/3rd the price of the Maynuo.  The build quality of the Maynuo makes me feel uncomfortable but no one has reported failures here; and the software for Maynuo and clones are superior, and has far more functions.  You may find the Array 3370/1a sold locally to your country from someone as a rebadged unit so there is less uncertainty buying it Internationally; if Gossen Metrawatt is will to put its name on the Array, it says something for their build quality.

https://www.gossenmetrawatt.com/english/produkte/ssl150300.htm

[saturation]

FWIW, quite a number of Maynuo variants are available from Amazon.com and some sellers ship from USA locally.

[linux-works]

for interest (and because I took a photo for someone), here is my array box doing a load test of a psu:



that array was $700 (sigh).  I paid extra for the gpib interface and also to get it from a US seller with a US warranty (in texas, I think that's still the US, lol).

it does not go up as high in voltage as I'd want (the Array) but its built pretty well, has a good UI, has ascii SCPI for remote mgmt and uses a simple and easy to get lcd display, so nothing custom or fancy here.  rotary wheel is nice and clicky and the front button arrangement is tasteful.  I like this box

[DaGlitch]

Just got a 3721A and was wondering if anyones unit sounds like mine. I can hear the fan just fine, but this sounds like something else. I didn't see any mention of the noise anywhere (or expected it) so I thought I would ask to see if this was normal. Cheers!

[sacherjj]

Just got a 3721A and was wondering if anyones unit sounds like mine. I can hear the fan just fine, but this sounds like something else. I didn't see any mention of the noise anywhere (or expected it) so I thought I would ask to see if this was normal. Cheers!

That sounds like maybe a fans running while rubbing on something.  The 3710 has two stages of fans, but they come on full, half, off cycle when powering.  So it doesn't seems like the sustained sound would be there if it was the fan.  Unless the control circuitry is messed up.

Although the insides of the 3710 and 3721 might be completely different.

[MarkL]

I have a 3723A, which is in the same product line, so I'd expect it to have a similar internal build as the 3721A.  The fans are noisy, and they also have the same "rubbing" or buzzing sound as in your video.  It's hard to tell, but yours might be a little louder.

I would take the cover off and check for anything obvious in the way of the blades.  There are two fans, at least in the 3723A, so try disconnecting one at a time to see if one of them is the culprit.

Test equipment manufacturers aren't generally looking for the quietest fans when spec'ing their parts.  You could always replace them with quieter fans with the same rating if it continues to bother you.  It might be a little work getting them out, though, since they're inside the metal air duct around the heat sinks.

Or, since it's new, you could ask for a swap for a different unit.

(Edit: Fix ambiguity.)

[saturation]

I think this is a teardown of this model lie from an archived post:

https://www.eevblog.com/forum/testgear/any-experience-with-scpi-and-chinese-dcprogrammable-loads/msg352717/#msg352717

@ MarkL, is this correct?

IIRC, the fans are on continuously in this model line?

Just got a 3721A and was wondering if anyones unit sounds like mine. I can hear the fan just fine, but this sounds like something else. I didn't see any mention of the noise anywhere (or expected it) so I thought I would ask to see if this was normal. Cheers!

That sounds like maybe a fans running while rubbing on something.  The 3710 has two stages of fans, but they come on full, half, off cycle when powering.  So it doesn't seems like the sustained sound would be there if it was the fan.  Unless the control circuitry is messed up.

Although the insides of the 3710 and 3721 might be completely different.

[DaGlitch]

Took the unit apart and it is definitely the fans. They aren't rubbing on anything and are just noisy. I can stop both of them and the unit becomes completely silent.  Inside my unit:

[saturation]

Thanks DaGlitch for that photo, it does look like MarkL's teardown device so the other images are from the same model line.

[MarkL]

I think this is a teardown of this model lie from an archived post:

https://www.eevblog.com/forum/testgear/any-experience-with-scpi-and-chinese-dcprogrammable-loads/msg352717/#msg352717

@ MarkL, is this correct?

IIRC, the fans are on continuously in this model line?

Yep, that's correct; those are my pictures.  Sorry; that's not really much of a teardown.  I was mostly answering a question about the built-in isolation.

The fans are always on in the 3723A, and they really get cranking if it gets hot while sinking a lot of power.

The unit, at least as supplied with the stock fans, is definitely not for those who want it quiet in their lab.  It doesn't bother me because there's already so much other stuff running.

It might be hard to find a very quiet programmable DC load that can handle a decent amount of power.  It has to dump the heat somewhere...

[Makerman69]

We've got 8 DC loads made by ARRAY in our lab. Plus  more than I can count of their programmable power supplies ( rebadged Circuit Specialists) No problems, they do what we need them to do and then some. Good build quality and terrific value. Can't ask for more. Some of the posts trash these because they are made in China . What isn't made in China? My understanding is that ARRAY is a Taiwan company and the engineering and quality are more on the upper end of made in China products.

[dolomike]

How well do the Array/Re-branded loads handle a PWM source?

We'd like to test out PWM based control circuitry but need something that can handle 5-20kHz PWM signal.

Mike

[forrestc]

Haven't ever put anything like that on mine, what type of wattage, voltage, frequency, filtering, etc. are you planning?

My guess is depending on the frequency it probably would work fine.  I know on mine (3711A) it seems to have a pretty good sized cap on the input---although I have noticed the ability to get it into oscillations where I have say a constant current source trying to drive it in constant power mode (I think that's the bad combination - if not, you get the idea).

-forrest

[dolomike]

Well, we normally run DC motors in automotive and heavy duty applications so this isn't a lightweight system. I think we would normally run CC or CR mode for most tests but some could be upwards of 800W. I believe this can be achieved by paralleling the devices in CC or CR mode. Some re-brands state they can be paralleled but I didn't recall seeing anything in the Array manual about it.

Voltage: 12V/24V nominal but some tests can be at 28V.
Current: ~10-15A but some tests may require almost 30A
Wattage: Most tests are done at 12V so we could do most of it with ~400W but if the parallel combos work, then we can get up to the ~850W for the extreme tests.
PWM Frequency: 5kHz-20kHz
Filtering: What type of filtering are you asking about?

I guess a lot depends on the current slew rate but the manual states 1mA/us~4A/us on CCH mode which is quite a range so not sure what the driving factor will be.

The transient generator can handle up to 50kHz so I would expect it could handle a PWM source upwards of that frequency as well.

Thanks for the feedback.

Mike

[nctnico]

I'm not quite sure a standard DC load will do what you want because the control loop will always lag behind and could mess with the control loop of the system you are testing. For this kind of tests I designed & build a switched resistor DC load myself. I can set it to a specific resistance and because its purely resistive it will keep that setting no matter what appears at the input.