By Sandra Cipriani, Product Manager
In high-stakes applications like EV battery development, even minor measurement drift can lead to major consequences. Calibration isn’t just a checkbox—it’s your assurance of accuracy, safety, and compliance.
Battery testers are the backbone of your validation process. But without regular calibration, their precision can quietly degrade—putting your product quality, regulatory standing, and customer trust at risk. With KeysightCare, calibration becomes more than maintenance—it becomes a strategic safeguard. In this post, we’ll explore why calibration matters, what’s at stake when it’s skipped, and how proactive service through KeysightCare can keep your test data—and your reputation—rock solid.
Batteries have become ubiquitous — and essential — to our daily lives. A day doesn’t go by when I’m not dependent on several devices that run on increasingly smaller, more efficient, and more powerful electronic batteries, from wearables, to smartphones, to electrical vehicles and so much more. They enable portability and flexibility in our lives, while also playing key roles in contributing to a cleaner energy future.
These days, battery performance can make or break commercial success of an electronic product. As such, test has become critical to ensure batteries perform as expected “in the field.” And with test, the age-old question always comes up: do I really need to calibrate my battery test equipment? Today, I’m speaking to Christopher and Jeff, both working in the Service Delivery Organization of Keysight, to explore the if, and why, of battery test calibration.
Sandra: Good morning, Christopher and Jeff. Thank you so much for joining me.
Over the years, I’ve heard so many people say: “I paid a lot of money for my battery tester; I expect it to be in specification for the life of the equipment.” Do you agree? Is the need to calibrate inversely proportional to the quality of test equipment?
Christopher: Thank you for having me, Sandra. This is a topic that’s near and dear to my heart, and that I talk to a lot of customers about. The short answer is no. Calibration should never be seen as optional, nor should it be viewed as a reflection of the quality of test equipment. In fact, quite the opposite is true.
It’s a fact of life that all electronic test equipment must be calibrated. Typically done annually, calibration is necessary to ensure that the equipment continues to provide the performance specifications that you require—and the performance you paid for when you made your equipment investment. As time progresses, all test equipment will slowly drift out of specification. Calibration with adjustments and optimizations, returns it to operating within its specifications.
In fact, it’s the highest-performance equipment that is the most critical to keep calibrated, especially because you paid a lot of money to get that performance, so it’s critical to maintain it.
Sandra: And is it specifically important for battery test?
Jeff: Most definitely! Your battery tester contains a charger (source), discharger (load), voltmeter to measure battery voltage, and an ammeter to measure battery current. For your battery tester, power source control must be carefully maintained, for example, to ensure a charger doesn’t overcharge a battery. Likewise, your battery tester is used where accurate measurement is needed, such as to report on the measured capacity of a battery. By following the calibration schedule for your testers, you can ensure your equipment performs at the desired peak performance.
Sandra: And what’s the downside if someone decides not to calibrate, or let’s too much time lapse?
Christopher: Once the calibration period expires, you can’t rely on the battery tester to provide its stated performance as this performance is neither guaranteed nor specified past the calibration interval. You are therefore risking your equipment drifting out of spec. This drift will mean that voltage sources might no longer source the voltage to the required accuracy, resulting in the wrong voltage output. Likewise, drift will cause measurements to have additional error such that you can’t trust the readings. Ultimately, you won’t be able to have confidence in the results, or worse, you might damage your battery under test.
Sandra: Can you say more about electronic drift – why and how it happens?
Jeff: Sure, put simply, electronics drift due to time and stresses of operation. While the test equipment was in perfect calibration when it left the factory, components inside will drift over time due to many factors, including mechanical shock (like dropping the instrument or roughly moving the system) or heat cycling (as the equipment heats up and cools down during normal operation). The purpose of performing calibration at set intervals is to ensure the battery tester is returned to its best calibrated state before it drifts out of specification.
Sandra: So how does drift specifically impact battery test?
Christopher: If we look at a battery voltage measurement as an example, say we want to measure the open circuit voltage (OCV) of a lithium-ion cell. The cell has an OCV of 3.5000V. This is the true OCV. Now we want to measure the OCV using the battery tester. Take a look at the table in Figure 1 (above) that shows how to determine the measurement error.
The issue is that without calibration, it’s possible to introduce even greater measurement error. If you were relying on this voltage measurement of OCV to terminate a charge step when measuring capacity, the capacity determination would be wrong because you stopped the charge step either too soon or too late due to the wide error in the OCV measurement. The voltage error then propagates into other measurements. Figure 2 (above) illustrates this point and shows how the measurement specification compares to the true or actual OCV.
For example, if the out-of-calibration measurement is +/- (0.7% of measurement + 8 mV), the error on the true 3.5000 V OCV jumps up from +/- 3.74 mV when in calibration to +/- 10.45 mV when out of calibration, resulting in a measurement that could be anywhere in the range of 3.48955 to 3.51045 V.
Sandra: That is a very significant deviation. So how do you recommend battery test equipment be calibrated?
Christopher: For large testers, the calibration service will likely be performed in your test facility, as it may not be feasible to move the testers. On-site calibration services can be pricey, so for benchtop battery testers, it may be more cost-effective to return the equipment to a qualified service center.
We caution about self-calibration. It is similar to deciding to fix your own car. Do you have the time, skills, and resources needed? If so, fixing your car is more cost-effective than having a mechanic fix the car. But if you don’t know how to make the repair, or need to buy a set of expensive tools, or simply don’t have the time, then maybe it’s better to let the mechanic do it.
Sandra: Christopher and Jeff, thank you so much for your time and expertise. As you know, Keysight offers certified, award-winning calibration services, including KeysightCare Enhanced support plans to take the work out of remembering when and how to calibrate. I’ll include the information below for our readers. Thanks again for sharing your experiences with us. Are you ready to discuss your calibration options?
About Jeff Massaro:
Jeff is a dedicated Field Service Engineer specializing in battery testing at the Keysight Huntsville office. His career began with an impressive eight-year tenure in the Navy, where he honed his skills working on Radar and Ultra High Frequency (UHF) applications before transitioning to the calibration lab.
In 1990, Jeff joined Hewlett-Packard at the Atlanta service center, where he focused on oscilloscopes and provided on-site calibration services for customers. His expertise and commitment led him to the field service organization, and in 1995, he relocated to Austin. There, he supported customers with Electric Magnetic Test (EMT) and semiconductor test equipment, further solidifying his reputation as Senior Field Service Engineer.
About Christopher Morton:
Christopher Morton is the EMEAI Business & Operating Manager in the Keysight Solution Service Delivery Organization. He began his career in 2000 as a graduate at Agilent, where he worked as a Test Technician and later as a Manufacturing Engineer on the 8960 Wireless Communication Test Set. In 2005, he transitioned into a Field Service Engineer role, focusing on In-Circuit and End-of-Line Functional Test solutions. Over the years, Christopher developed a strong foundation in the commercial aspects of the business, which led to his progression into management. He now leads the onsite Solution Service Delivery Organisation for Keysight across the EMEAI region.
