[RE-wrenches] Load testing Lithium battery bank

Wed Mar 18 11:13:41 PDT 2015

We're leaning toward the LiFePO4 batteries (low internal resistance) GBS have  a medium high resistance so they warm faster and have a lower C rate efficiency, were gathering info as we go...... Max Balchowsky
Design Engineer
Golden Bridge Development
1048 Irvine Ave Suite 217
Newport Beach, Ca. 92660
760-403-6810"Building a Better Future For The Next Generation"

      From: Larry <larry at starlightsolar.com>
 To: RE-wrenches <re-wrenches at lists.re-wrenches.org> 
 Sent: Wednesday, March 18, 2015 8:57 AM
 Subject: Re: [RE-wrenches] Load testing Lithium battery bank

 Hi Jarmo,

 I agree and recognize your urgency in making us aware of the proper use and charging of Li-ion batteries as well as the dangers of mistreating them. As an early adopter myself, I am very cautious in my approach even to the point of refusing to sell to some customers. Lithium battery technology is in a state of rapid evolution. 

 Not wanting to harp on the GBS brand that I sell, but one of your points goes to prove the safety of their integrated approach. You said, "...all it takes is one poor connection or broken temp sensor on one cell." The GBS EMS system has cell level sensors for temperature (and other data) and each sensor board requires constant communication with the CPU. If the EMS fails to communicate any information with any cell, the CPU immediately shuts down both safety solenoids, disconnecting the battery. With the non integrated systems, failures that don't report information to the management system could lead to disaster.

 Please keep offering us the knowledge you are gaining as I am a firm believer that Lithium technology is a large part of the inevitable replacement the aged lead battery.
 Larry Crutcher
Starlight Solar Power Systems

On 3/17/15 6:11 PM, Jarmo.Venalainen at schneider-electric.com wrote:

Hi: 

 I may sound like I'm a detractor against using Lion, but that's not it. 

 What I want to bring to light is that, being as the technology is new, not all the issues are known and there are things to learn for all early adopters in the foreseeable future. 

 From what I can gather the framework for the issues lies in that Lion technology is based on intercalation, that is, a reversible insertion and removal of Li molecules into compounds with microscopically layered structures.  This predicates that there must be no chemical reaction in the battery, but rather only the shelving of the highly reactive Li ions.  If there are any chemical reactions taking place, then in the least the battery performance is compromised and in the most there is a thermal event or worse 

 There are some very robust Lion battery packs, a favorite of mine being from a local company from Vancouver, (well Richmond, which is a suburb of Vancouver).  It's a small company, but they have designed, developed, built and successfully approved their 6 kWh Lion pack for use in large car ferries in Scandinavia.  The ferries have stacks of these packs in the 100's, in the MWh size.  It can be done. 

 What I'm advocating is that its best to work with companies that have the time, interest and resources to work through the wrinkles, and if not, then carefully put in reliable and precise BMS circuitry which includes things like fail safe circuits for single point failures of critical sensing circuits, the foremost of which is cell temperature.  When you're pushing large currents, all it takes is one poor connection or broken temp sensor on one cell...... 

 Here's a link to the Lion battery pack manufacturer, Corvus, 

 http://corvus-energy.com/ 

 I know they do a good job, but they're not cheap,.... for now... 

 JARMO 

 Jarmo Venalainen  |   Schneider Electric   |  Xantrex Brand  |   CANADA  |   Sales Application Engineer 
 Phone: +604-422-2528  |   Tech Support: 800-670-0707  |   Mobile: +604-505-0291 
 Email: jarmo.venalainen at schneider-electric.com  |   Site: www.Xantrex.com  |   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 

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