Author Topic: Why is BK Precision still in business? BK8500 programmable load OEM found  (Read 57738 times)

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Offline eevblogfan

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hey

it's fairly easy to upgread the power supply to have remote sense , if you'd like please PM me and I'll show you :)
 

Offline metalphreak

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Testing a turnigy nano-tech 3S 1000mAh lipo @ 10A. Total capacity 990mAh. Usually ratings are done at 1C discharge as well not 10C like I did. Saving the image with the maynuo software doesn't show any of the values at the bottom of the graph which is annoying (just title and the line colour legend). The one above is a screenshot instead. You can export the dataset to Excel which works ok. Exporting to Word just spawned a winword.exe process that did not much besides chew some CPU time.

There is a capacitor test function shown in the battery test software page. Haven't had a look at that yet. I think it may be time to start my own thread and do a write up once I've tried out all the features :)


The best thing about these is the ability to remote control them. The commands are fairly basic 26byte serial packets. Imagine one of these combined with a programmable power supply. You could automate testing of Linear/Switchmode designs by doing a whole bunch of test measurements at different load levels, input voltage, output voltage etc.

Offline HKJ

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The best thing about these is the ability to remote control
them.

That is a very useful feature, I have using two of these load to mostly test batteries with, they have been running 24/7 for about a year with computer control. The computer does also  control a power supply and a relay box to control charging.
 

Offline gerrysweeney

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I all, I noticed this topic and have recently done a full video teardown of the Maynuo M9711 DC Electronic Load so you can see whats inside.

http://gerrysweeney.com/maynuo-m9711-dc-electronic-load-unboxing-teardown-and-quick-test/

Gerry

darciop76

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Great review Gerry!
 

Offline saturation

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+1  :-+ Great way to contrast against Dave's BK 8500 review.

There is a review of the Maynuo elsewhere on eevblog with input from LawrenceW and myself.  One thing I'd like to see with your feedback later is not that it performs what it does which you showed, but that the unit doesn't fail after prolonged use at near or max load, ~ 150W.

« Last Edit: April 18, 2013, 03:52:29 pm by saturation »
Best Wishes,

 Saturation
 

Offline Salas

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I all, I noticed this topic and have recently done a full video teardown of the Maynuo M9711 DC Electronic Load so you can see whats inside.

http://gerrysweeney.com/maynuo-m9711-dc-electronic-load-unboxing-teardown-and-quick-test/

Gerry

Nice report. Sounding like a BBC pro presenter at times. 8)
 

Online Electro Fan

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I'm very late to this thread but two comments:  I think BK is an A-ok company.  They make good gear, they have lots of good distributors/resellers in their channels (customers can pick from a good variety of sellers), and they will definitely answer their phone and give you prompt, couterous, and knowledgable personal service.

Having said that, whether it's the 8500 or one of it's ancestors, recent predecessors, off-spring, other relatives or acquainteances somewhere in the world, or just a member of it's peer group from who knows where in the competitive landscape I'm of the opinion that the 8500 is a great electronic load and that electronic loads are one of the coolest and most useful pieces of test equipments you could have on your bench. 

We could start another thread on this (or just do it here), but if I were assembling a few key pieces of gear to help learn and develop basic electronics skills and headed toward the basic electricity/analog realm and the digital realm, I'd go with:

PC with access to the Internet
DMM
oscilloscope (preferrably mixed signal with Logic Analyzer)
power supply (prefferably programmable)
electronic load (preferrably programmable)
signal generator
soldering iron

Maybe in that order - although I'm sure it depends heavily on what you are trying to build, fix, learn, and I'm probably forgetting something(s).

Althlough I don't have one (yet), that 8500 sure looks like a very useful device for making sure you are on top of Ohm's Law and more.  And just because someone might have gotten a bee in their bonet about BK at some point, I don't think we want BK to disappear; I don't think that would do anyone any good.  Healthy choices for EE-land are better than limited choices.

PS, thanks to LaurenceW, saturation, and everyone else on this thread for all the good info!



 

Offline Mike Warren

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I received a REK RK8511 yesterday. First thing I did was test it at 150W. After about 5 minutes it shut off due to thermal overload. On inspection, I discovered that the fan was barely running.

I modified the fan control circuit by changing R31 from 10K to 4.7K. My guess is that the fan fitted to this unit draws slightly more current than the one the circuit is designed for. The drive for the fan is simply a TIP41 to ground, controlled by a LM324 and the bridge rectifier. A very simple idea, and effective as long as components aren't substituted, but not how I would do it. A different fan would change it's operating parameters significantly.

After running it for an hour at 150W it was still working fine and the heatsink temperature was stable.

This is obviously basically the same design as the BK Precision and Maynuo, but there have been some corners cut. The heatsink is just held off the case by a couple of spacers instead of being screwed down and the most serious thing is that there is no stand-off near the power switch. This causes the PCB to flex badly every time it's turned on or off.

Mine now has a stand off fitted.
 

Offline gerrysweeney

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I all, I noticed this topic and have recently done a full video teardown of the Maynuo M9711 DC Electronic Load so you can see whats inside.

http://gerrysweeney.com/maynuo-m9711-dc-electronic-load-unboxing-teardown-and-quick-test/

Gerry

Nice report. Sounding like a BBC pro presenter at times. 8)

Thanks, thats nice of you to say...I need much more practice
« Last Edit: April 19, 2013, 08:29:54 am by gerrysweeney »
 

Online Electro Fan

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Maynuo M9712 Electronic Load
« Reply #110 on: July 25, 2013, 01:50:32 am »
I'm thinking about acquiring a Maynuo M9712 - I have hunch it would be a very cool testing/teaching/learning tool.
 
I'm using a 30V 5A DC power supply with over voltage and over current protection.  I'm just doing simple Arduino stuff, teaching myself some basic electronics, etc. Seems like 300 watts, 150 volts, and 30 amps on the M9712 should keep me out of trouble but are there any "uses cases" or likely/typical combinations of settings that anyone can think of that would potentially cause a user (me) to exceed the specs of the M9712 and cause any damage or danger?

It isn't clear what the maximum resistance is that the M9712 will support; the spec sheet references 5K and 10K ohms, but I don't know if either of those are the max.  Anyone know?

Seems like watts are always something to keep an eye on if you don't want to cook a resistor, but at 300 watts it seems like there should be some head room.   

When one or more of the specs on the M9712 are exceeded does the unit gracefully protect itself and any attached devices?

I'm trying to create a safe test environment but I don't want to get too trusting, so anything you've learned to avoid given all the experience you EEVers bring would be appreciated.  Just trying to stay on the lookout for personal and equipment safety.  Thanks
 


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