At Embedded World 2026, one demo stopped me longer than any other.
Not because of the instrument specs. Not because of the software. But because of what was sitting on the bench next to the R&S NGU501 battery emulator: an Apple Watch. Connected. Being discharged. Its current profile — every BLE burst, every sensor poll, every sleep cycle — appearing live on the display as a real-time current curve.
This is what battery emulation looks like in 2026. And it is changing how every team building battery-powered hardware validates their products.
R&S Battery Emulation and Battery Testing demo — Embedded World 2026, Nuremberg. The large displays show the R&S Application Suite control software (left) and the ZES ZIMMER LMG600 Precision Power Analyzer measuring live power parameters. Photo: Thomas @SignalByThomas
The Problem With Real Batteries in a Test Lab
If you have ever tried to characterize the power consumption of a battery-powered device using a real battery, you already know the problem.
A real battery is an uncontrolled variable. Its voltage depends on state of charge, temperature, and aging. Its internal resistance changes over thousands of charge cycles. If you run the same test twice with the same battery, you do not get the same conditions. And if something goes wrong — a firmware bug that causes excessive drain, a short circuit during bring-up — a real battery can be unpredictable in ways that are expensive or dangerous.
The engineering solution is to replace the battery with an instrument that behaves like a battery but is fully under software control:
→ Programmable voltage (following a real discharge curve)
→ Programmable internal resistance
→ Source and sink capability — it can both supply and absorb current
→ µA-level current measurement
→ Microsecond-level dynamic response
This is what a battery emulator does. And the R&S NGU series is one of the most capable instruments in this category.
Left: R&S battery emulator front panel showing active discharge state — 79.6% SoC, 716 mAh remaining capacity, 3.010 A discharge current. Right: ZES ZIMMER LMG621 Precision Power Analyzer measuring system power parameters in real time. Photo: Thomas @SignalByThomas
What the R&S NGU501 Was Doing on That Bench
The NGU501 front panel showed something immediately striking: −2.967 A. Negative current. The instrument was in sink mode — absorbing current from the DUT rather than supplying it.
This is the source/sink capability that separates a battery emulator from a standard bench power supply. A real battery can absorb regenerative current. A standard power supply cannot. The NGU series replicates this behavior, which means the DUT never "knows" it is connected to a test instrument rather than a real cell.
The display was also showing battery state of charge: 79.6% in discharging mode, with an internal resistance of 0.076 Ω and a capacity of 905 mAh — parameters loaded from a real battery model, not invented values. The emulator was tracking a real Li-ion discharge profile, voltage dropping from 4.2V toward cut-off as capacity was consumed.
The Apple Watch Detail
The Apple Watch on the bench was not decoration. It was the device under test.
Wearables are one of the most demanding applications for battery emulation, precisely because their current profiles are so dynamic. A BLE advertisement burst draws 10–20 mA for microseconds, then drops to sub-microamp sleep current. A heart rate sensor poll creates a brief spike. A notification display-on event draws tens of milliamps for a few hundred milliseconds.
The current logging curve on the center display told the story: a baseline near zero, punctuated by sharp current spikes — each one a real event in the watch's operating cycle. The peak current was visible, the average was measured, and the battery capacity consumed over time was calculated automatically.
This is the information a firmware team needs to optimize sleep states, reduce BLE advertising frequency, or understand why the battery is depleting faster than simulation predicted.
The ZES Zimmer Power Analyzer: The Other Half of the System
Alongside the NGU501 sat a ZES Zimmer LMG671 precision power analyzer. This instrument was measuring power at the supply input — not the battery emulator output, but the AC side of the system.
The display showed power parameters measured to nanoWatt precision: P −24.5769 nW, S 29.6084 nVA, Q 16.6705 nvar. These are vanishingly small values — the kind of measurement that matters when you are trying to characterize a device in deep sleep mode consuming sub-microamp current at a few volts.
The combination of NGU501 + ZES Zimmer covers the full measurement chain:
→ NGU501: emulates the battery, measures device current consumption (µA resolution, µs response)
→ ZES Zimmer LMG671: measures true power at AC input with nW precision
→ Software: correlates both datasets, calculates battery life, generates reports
Why This Matters for Embedded Hardware Teams
Battery life is the number one complaint from end users of battery-powered products. And it is almost always a firmware problem — not a hardware problem. The hardware draws the current it is designed to draw. The firmware decides when, how often, and for how long.
Battery emulation makes firmware-level power optimization measurable and repeatable:
Reproducibility: Every test run starts from exactly the same battery state. No drift between test sessions due to battery aging or temperature variation.
Safety during bring-up: A firmware bug that causes unexpected current draw trips the emulator's software limits — not a thermal runaway in a lithium cell.
Speed: Testing a full discharge cycle on a real battery takes hours. A battery emulator can compress or expand time, or test specific SoC windows in isolation.
Automation: The NGU series supports SCPI control and integrates with standard lab automation frameworks. A full battery life characterization test can run overnight without a test engineer present.
The Broader Trend This Demo Represents
At Embedded World 2026, battery emulation appeared across multiple booths — not just R&S. This is a market that is growing because the products feeding it are growing: IoT sensors, wearables, BLE devices, LoRa nodes, industrial wireless, medical implants.
Every one of these products is battery-powered. Every one of them ships with a battery life specification that has to be validated before production. And every engineering team that has tried to validate battery life with real batteries in a production test environment has eventually concluded that there has to be a better way.
Battery emulation is that better way. And the tools — from the NGU501 down to more accessible entry-level emulators — are now within reach of teams that are not working at the scale of a Tier 1 automotive supplier or a major consumer electronics manufacturer.
If you are building a battery-powered product and you are still validating power consumption with a real battery on your bench, this is worth a second look.
Observed live at Embedded World 2026, Nuremberg. Equipment: R&S NGU501 battery emulator, ZES Zimmer LMG671 precision power analyzer, R&S NGU201. All photos: Thomas @SignalByThomas