I recently had the good privilege of being selected to receive the Keysight E36731A Battery Emulator and Profiler as part of Element14's roadtest program. Now, batteries might not be everyone’s cup of tea, but having spent some years working with them across various products, I find them quite fascinating! So, you can imagine my thrill when the unit arrived, primed for a deeper dive into the world of battery testing and emulation!

Introduction

Let’s talk about the Keysight E36731A Battery Emulator and Profiler. This isn’t just another run-of-the-mill piece of equipment; it’s a sophisticated blend of electronic load, power supply and clever software, designed to offer a one-stop solution for battery profiling and emulation. It doesn’t just promise comprehensive battery characterization; its unique ability to emulate any battery charge state sets it apart. This feature could be a game-changer when assessing the impact of design or software changes on battery life. With it's power capacity of up to 200W, a current limit of 20A, and a voltage ceiling of 30V (power supply mode), it’s poised to be a robust and versatile addition to any workbench.

Over the coming weeks, I’ll be exploring this device’s capabilities in detail and look forward to sharing my journey in subsequent blog posts. At the moment, I’m awaiting the PC software license for the unit, which will unlock its advanced profiling and emulation capabilities. In the interim, I thought it would be worthwhile to share my initial impressions of the device.

Packaging

Normally, I don't obsess with the packaging much. For all my previous roadtests, the devices came in secondary packaging (on top of the original device packaging). However, for this shipment, I noticed that the packaging was actually the original Keysight packaging. This means that anyone ordering this device would receive it packaged the same way.

The box was big and somewhat heavy (the shipping notification mentioned 24 lbs). This is because, for one, the device inside is bigger and heavier than usual benchtop equipment, and secondly, because the packing materials are also very strong. I noticed that the same box had originally been used to ship the unit from Malaysia (where it was built) all the way to the US, and then from the US all the way to my country. In all this traveling, I could only see some very minor dents on the box.

Inside the box, I found the device surrounded by some more packaging and a box with accessories placed on top.

The E36731A instrument itself was protected very well because it "floats" in the middle of some extra packaging that should keep it secure from bumps from all directions, while also absorbing shocks and vibrations during travel. Overall, the packaging is simple and very well done.

And here it is—the E36731A in all it's glory!

It's not very visible in the picture (thanks to the warm lighting in the room, and color grading done by my camera), but the device's sheet-metal body actually has a nice dark-silver-gray colour. The front panel looks like industrial plastic in a dark gray colour. Over-all it's a beautiful instrument!

Contents

The package contained everything promised in the documentation:

• E36731A Battery emulator and profiler instrument
  • Came installed with the rear output connector 
• Box of Accessories, containing:
  • AC power cord (A beefy cord, but unfortunately not the EU plug used in my country. This was easy to replace though)
  • Certificate of calibration
  • One detachable front output connector
  • One rear remote sense connector (2-way, black)
  • One digital IO connector (4 way, green)

Form Factor, overall build

As I mentioned earlier, the device is not the lightest. Usually I can use my wife's kitchen scale for weighing such things, but this time I had to use my shower weighing scale since it exceeded the weight limit of the former. Just the E36731A, with the front output connector installed, weighed ~8.4kgs as per the scale.

It's definitely going to be one of the heavier instruments on the bench; however, this weight class is nothing new about many lab bench power supplies and Electronic Loads. In fact, the Kikusui DC Electronic Loads that I have mostly used at work weigh roughly the same. Also, when you consider that this is a multi-instrument (power supply + electronic load), it definitely doesn't weigh as much as a set of discrete power supply + electronic load with similar power ratings!

The device is very well built. The front is mostly industrial plastic, but the rest is all sheet metal. I believe the sheet metal contributes a major amount to the weight. However, it's not thin-gauge sheet metal that bends or deforms easily. Frankly, using a plastic casing on a device that needs to dissipate so much heat (200 W in Load mode) would not have been wise anyway. Overall, I like the design choices made here and the overall build of this instrument.

The Keysight designers have also included a carrying handle on one side, which enables one-hand carry. This has been my main "carrying mode" so far, and it works for me.

While looking around the device body, I also noticed a cable lock close to the carrying handle. I think for an instrument in this price range, it's surely a good thing to have! You never know where your adventures will take you! 

The instrument also comes with removable legs at the bottom that can raise the front by about 8cm. I was happy to see metallic legs here instead of the plastic legs on most instruments. I am not sure if it's the humid weather where I live or rough handling, but I see the plastic legs being the first things to break on a lot of instruments. If you need to remove them (for example, when mounting in a rack), the leg assemblies are easily removable by just pulling out the plastic tabs, leaving a flat bottom surface.

Device Interfaces

All the device interfaces are on the front and rear of the device, as expected.

On the front side, you get the main connector (right) for connecting your Device Under Test (DUT) such as a battery, some load, or some power source (depending on the testing mode). Just besides that you have the Sense + and - ports for 4-wire operation. From my experience working with batteries, these are a lifesaver (a MUST!) when you're dealing with higher-power batteries or loads. For low-power use cases, the instrument supports 2-wire operation in all modes too. There is also an earth port besides these if you need to use an earth reference (the instrument is otherwise "isolated").

When I first saw the instrument's picture earlier in the year when it was released, I thought the connector on the right was for Electronic Load and the ports on the left were for the power supply. That would have given the possibility (in theory at least) of operating the device in Power supply and electronic mode simultaneously (on independent ports). However, I later found out the ports on the left are the sense and ground connections, and basically you can use the device in either source OR load mode at one time.

If connecting to the front side is not desirable or feasible, then the back side also provides the main connection ports as well as the sense 4-wire kelvin port (The mating connector is provided amont the accessories).

You also get a USB port, a LAN port, and a digital IO port on the back. On the left side, you may notice what looks like an expansion port, currently covered. I assume this is for optional expansions to the instrument, not included by default.

Coming back to the front side, the main front output connector is a detachable one. There are poka-yoke features on the connector as well as mating surface to only allow connections in one orientation; always a good thing for high-power instruments.

When installed, the wires will go into the connector from the bottom side only. The removable nature of this connector is good because sometimes thick wires are not so easy to insert or remove from connectors in certain orientations, so you can install the wires in the connector first and then mount the connector to the device face. Screws on both sides will secure the connector in place.

Without the front legs at the bottom extended, you get ~18mm of space for the wires to go in, which can be a bit tight (wires can only go in from the bottom side!).

However, with the front legs extended and the body raised, you get plenty of space (>80mm) for even the thickest wires you'll use with this instrument.

Front Panel Interface

This brings us to the main "business end" of this instrument: The front panel. This (beautiful) panel has all the controls most users will be using most of the time. The only thing inaccessible from the front are the GPIO port connections (at the back of the device).

It really is a beautiful instrument!

Overall, the quality of the knobs and buttons on the front panel feels excellent. The buttons have good travel and tactile feel. There is also a beep sound as feedback when any button is pressed. The Output on/off button (yellow colored) has a bright LED behind it which lights when the output is turned on so it's very visible.

The power button is a non-latching type. I think it's good from a safety perspective because if, for any reason, the instrument loses power during operation, it will not turn back on when the power is restored, except by manually pushing the button.

The screen is NOT a touch screen. The knobs and buttons control everything. The size of the screen and UI element design is done accordingly.

You might notice the Moire pattern on the screen. This is actually not from the screen itself but rather the protective sheet the device comes with. If I remove it, there is no Moire pattern visible anymore (compare the left half vs right half in the image below).

Without the device connected to the PC with Keysight software, you can use it in one of the two below modes:

• Power supply mode
• Load mode

Each mode has its own set of options (Source/output modes and settings, sequencer, independent slew rates for power up/down, on/off delays, protection features, etc)

Switching between Power supply and Load modes is done with pressing the bottom-left button.

As you would expect, the output is turned off when you switch between modes.

As with the Power supply mode, the Load mode also has plenty of options. You get all four modes you'd expect from a good Electronic Load:

• Constant Current (CC)
• Constant Voltage (CV)
• Constant Resistance (CR)
• Constant Power(CP) 

And then, each mode has it's own settings and options (range settings, slew, delays, protections, sequencing, etc) 

Frankly, even just as a power supply or Electronic load, this device gives you so much control over your power supply /load settings that you don't normally get with most discrete power supply or electronic load instruments. I am still exploring all the options that this instrument provides!

You also get a USB port besides the screen where you can connect a USB disk to capture screenshots (long-pressing the "Meter view" takes a screenshot).

At this point, I haven't explored if this USB port serves other functions also (or not).

This device also comes with some more neat features that I haven't talked about at all, including Sequencing lists and scope functionality, etc. I plan to explore and use them more and will write about them in a future post. 

One thing I found a bit odd is the way the Lock/Unlock feature works. What I expected was that I'd need a long-press to lock the controls, which is how it works. However, to unlock, all it takes is a momentary press of the same button instead of a long-press. I feel this is not good as one could accidentally press/bump the unlock button (higher chances of accidental press than long-press) and unlock the controls. The unlocking should be harder than locking the controls! In this case, it's the opposite. Perhaps something Keysight can address with a software update.

Summary & Conclusions

• The E36731A is a very well-built and beautiful instrument!
• Without the Keysight Battery emulator PC software, it is still a very feature-rich single channel Power supply and Electronic load instrument (one at a time, though!). It gives a lot more features for these instruments than most discrete instruments of the same type you'll use.
• The user interface is not a touch interface. It is well implemented but is taking some getting used-to (for me, at least)
• The way the lock/unlock feature is built may need some rethinking.

Over the coming weeks, I’ll be exploring this device’s capabilities in more detail and look forward to sharing my journey in subsequent blog posts. Thanks for reading ,and see you next time!