Battery Management Systems Workshop 2011 Notes
A Battery Management Systems (BMS) Workshop was held on Monday, September 26, 2011, during the Annual Conference of the PHM Society 2011 (PHM’11). The goal of the Workshop was to discuss the emerging art and science of battery and power management for electric and hybrid vehicles as well as other mobile applications. A secondary goal was to document and benchmark the state-of-the-art in battery SoC and SoH estimation. A third goal was to discuss methods and strategies for acquiring public-domain data sets and performance models for battery usage and aging that can be used to benchmark future efforts in SoC and SoH estimation.
The Workshop was well attended, with nearly 60 international participants from industry, academia, and government. The workshop agenda may be found here.
Invited presentations:
Notes from panel sessions
Industry Needs Panel Session
Speakers:
Ed Andrukaitis – Canadian military R&D
Dan Boyer – Battery manufacturer
Lembit Salasoo – GE global research (battery and BMS development)
Martin Klein – LG Chem
Xia Guang Yang – Ford
Questions
1. What are greatest challenges in BMS today
• Ed
○ Safety (penetration from ballistics or fragments
○ Operation over wide range of temperatures
○ Battery life drives shelf life of systems such as sono bouys – need accurate diagnostics and prognostics to extend rated life.
• Dan
○ Fewer people available to do battery maintenance and testing so need to have BMS to reduce manpower requirements
○ User error in measurements with handheld systems results in excess cost
○ Need prediction of RUL for stationary lead-acid batteries
○ Trying to retrofit legacy lead-acid battery applications (such as telecom) with Li-ion results in having to comply with legacy requirements for telecom battery systems based on lead acid batteries (no embedded electronics) so BMS must address PM and other testing requirements
• Lembit
○ Need standardization in BMS
○ Need RUL
• Martin
○ Cost reduction
○ Thermal management
§ Extend operating range (temp) and life
§ Extending life allows reducing number of cells required ($$)
○ SOC accuracy
§ Allows you to get rid of extra cells to cover possible error in SOC estimate
○ Improve validation and modeling of cells
§ Need 2-3 years of testing to validate cell rated for 13 years
§ Better modeling and simulation would help reduce cost
• Xiao
○ Keep BMS design simple
○ Need standard tool for applying PHM analysis
○ Cell evaluation in degradation models
2. Where do you think solutions will come from? Small companies, large companies, universities, government, …
• Ed
○ Currently behind on management piece, hard to say where solution will come from
○ BMS system needs to be plug-n-play, integrate with battle management system
○ Military will probably not go out and develop it themselves, but look to tier 1 suppliers for solution
• Dan
○ Government funding has driven most of the R&D for now
§ After hurricane Katrina, government threatened to require cable carriers to provide backup power to ensure internet and phone in event of power outage – 6-8 hours of backup power required for phone companies (systems are located on the pole)
• Lembit
○ Government needs to create University based centers of excellence in battery and BMS technology
○ Need for honest brokers to test both batteries and in the future BMS
• Martin
○ Company lead, with university collaboration
• Xiao
○ Would like to see University and National Labs working together to develop new battery and BMS technology
Audience questions:
• Does industry really want development at universities or would rather just work on their own
○ Martin – yes, interested in collaboration
○ Dan – look to universities to fill voids in corporate capability
○ Xiao – currently working closely with universities
• If industry wants the government to pay for R&D, is industry willing to provide requirements, use cases, etc. to drive R&D?
○ Xiao – industry doing that as part of battery consortium
○ Dan – have requirements and some data that could be used for stationary batteries
• BMS research really isn’t fundamental R&D (at chemistry level, etc.) but is more along the lines of engineering. Is industry willing to fund basic R&D instead of only funding targeted (narrowly focused) research
○ Martin – cell chemistry is closely guarded IP, as is details on BMS design
§ Hesitation to share too much information to avoid having battery become commodity
• Is there interest in reusing battery packs as way of recycling batteries?
○ Martin – there is interest, but nobody knows how much life you would really get out of the battery after it’s reached its end of life (e.g. 70% of original capacity)
○ Xiao – automobile companies working on this
• What would be an acceptable cost for the BMS re the cost of the battery pack?
○ Martin – probably below 10% as piece price (cost of electronics)
• What area needs better requirements to help move development forward
○ Ed – military can’t provide good numbers for actual power requirements (typical requirement is to reduce energy use by X%, but that does not translate well into what the battery and BMS needs to do)
○ Dan – In cases where they are trying to replace led acid batteries with Li-ion, it’s difficult to translate requirements
○ Lembit – many requirements are translated from ic engines and are not written specifically for battery systems
§ Few of the requirements consider user habits (e.g. plugging in your car when you get home)
○ Martin – early specification was 7 pages, latest revision was hundreds of pages as requirements evolve
○ Xiao – requirements for HEV and PHEV are still evolving
§ Look to USABC for requirements and guidance
• How much use does BMS need to track for insurance and warranty purposes
○ Martin – at first, automotive companies probably won’t push back as a customer relation move
R&D Directions Panel Session
Panelists:
• Giorgio Rizzoni (OSU) – safety
• Mutasim Salam (GM) –
• Jon Christophersen (INL)
• Humberto Garcia (INL)
• KaiGoebel (NASA)
Are SOC and SOH algorithms ready for deployment?
• Mutasim – need better modeling to support testing and validation
• Humberto – need more sensitivity analysis to understand where shortcomings are
○ Measurement -> model -> estimation algorithm
• Kai – depends on application area (camera or laptop vs EV)
Challenges
• Mutasim – algorithms from universities often require a lot of modification
• Jon – sometimes National labs and universities are needed to address problems that battery manufacturers don’t want to tackle (e.g. extending battery life to 15 years)
• Humberto – need better approaches to making high level decisions based on uncertain local measurements
○ We can do pretty good working on local information, but have problems extending that to multi-element systems
• Kai – there is always a gap when trying to transition from low-TRL to fielded systems. In particular, R&D is always moving forward, while fielding systems requires freezing technology in order to mature it.
Value in large open data set for BMS development
• Good testing is expensive
• Need standards for testing to be able to accurately characterize the data
○ Need to know temperature, chemistry, load profiles
• Want neutral third party to do the tests
• Idea
○ Publish guidelines for battery testing
○ Publish guideline for supporting data that needs to be supplied with data (test plan, load profiles, temperature, voltage, current, etc.)
○ People submit data with supporting information
○ Users can vote in utility of data after downloading and using data
General comments
• Question for group from Giorgio
○ Need to consider cost of battery system in addition to the cost of the cells. Need to not only reduce cost of cells, but also cost of system
• What is the cost of availability? – Dynamic cost analysis of cost of operating system under difference use profiles.