Millbrook battery testing facility looks at modules and complete assemblies across a range of tests for performance and crashworthiness.
In October 2019, automotive engineering and testing organisation, Millbrook opened its Battery Test Facility for the provision of independent automotive battery testing.
Consisting of 12 battery cycling climatic chambers and supporting infrastructure, the facility represents the biggest private investment in such testing in the UK so far.
Four months on from the opening ceremony, I spoke to the Chief Engineer responsible for battery testing at Millbrook, Peter Miller.
According to Miller, battery technology is evolving at a staggering rate as the industry seeks to make electric vehicles universally accepted as an alternative to the internal combustion engine. “We pride ourselves on our in-depth knowledge of battery technology and our ability to provide testing which helps developers better understand, anticipate and ultimately eliminate failure in future models,” he says.
Millbrook already enables its customers to assess the performance of battery cells, modules and packs, determine pack performance during a crash event and subject batteries to a range of environmental conditions.
Millbrook offers 48V hybrid test cell capability, full EV durability testing and electric machine and inverter testing. Its facilities are suitable for a range of tests on the latest generation of vehicle powertrains – including mild hybrids (MHEV), plug-in hybrids (PHEV), battery electric (BEV) and fuel cell vehicles (FCV)
The battery test chambers can cycle complete automotive battery packs up to 1,100V and up to 750kW in temperatures from -40°C to +90°C, including simulation of rapid temperature changes.
Important factors that consumers consider before making the switch to electric cars are range and reliability. Vehicle OEMs are keen to understand the life cycles of the battery equipment they use and how they can extend existing warranty lengths to attract more buyers.
The life testing facility at Millbrook is able to provide insight into expected reliability through accelerated life testing. According to Miller, it takes 1 year to measure a 10 year life and it isn’t possible to accelerate beyond this without over-stressing or over-heating the parts under test.
“With batteries, the margins are quite small so stressing them too much changes the characteristics to a point where the test becomes invalid,” he says.
Currently, the industry is taking a cautious approach until more data is available and is in a constant process of learning from test and field data to refine future products.
Miller says the cooling systems and electronics are already established technology and so reliability and longevity are predictable. The chemistry is the part that’s new and needs testing fully.
When asked what factor most influences reliability, Miller explains that temperature is the biggest factor rather than current. “Temperature control is crucial because for every 10 degree C increase in temperature, the live expectancy can be halved,” he says.
Millbrook also has a group of independent researchers, who are focused on in-house testing on battery safety and abuse. This contributes to the general body of knowledge on the subject.
Such testing covers altitude, thermal, short circuit and over-charge testing as well as crush, over discharge and fire resistance testing.
Millbrook is also able to perform crash testing on electric vehicles as some crash test facilities are unable to perform such tests because of the post crash hazards of EVs.
Overall, with its latest addition to the testing facilities, Millbrook can offer the complete range of tests needed for battery and hybrid vehicles, including cell, module, powertrain testing and crash testing.
For the future, as demand starts to ramp up, Millbrook will be ready. “Both Millbrook and the industry in general is investing heavily now and expects to continue to do so in the future,” he concludes.