[RE-wrenches] Load testing Lithium battery bank

Tue Mar 17 18:11:40 PDT 2015

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 

*** Please consider the environment before printing this e-mail

From:
Larry <larry at starlightsolar.com>
To:
RE-wrenches <re-wrenches at lists.re-wrenches.org>, 
Date:
03/17/2015 02:37 PM
Subject:
Re: [RE-wrenches] Load testing Lithium battery bank
Sent by:
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>

Hi Jarmo,

One of the reasons I chose to sell and install GBS batteries is the 
chemistry is safer, they have vent caps (like AGM) and they offer an 
integrated solution where the battery, EMS/BMS and CPU are all designed 
specifically for each other instead of adding various parts from different 
manufacturers. The chemistry is LFMP (lithium iron manganese) not LFP. 
There are seven monitored fault events, including temperature, current and 
voltage, that will disconnect the battery from any load or any charge 
source. 

Since we are installing in RV's, there are multiple charge sources and all 
must be controlled. The systems I design do this very well. Also, our 
charge and discharge rates are far lower than the industry normally 
expects; rarely reaching .5C. 

I have seen private videos of destructive testing of GBS cells. Steel rods 
fired through entire packs; slow crush tests from top and sides, impact 
tests, even cells blown away on a gun range (that was more for fun I think 
as not too likely you will experience that). No fire, no thermal events. 
Bottom line for me is these are likely the safest Lithium battery I can 
offer. Many customers have already had shut down events because they were 
not being responsible. A simple reset and they're back in business. 

What was the lithium chemistry that you had trouble with?

Thank you,

Larry Crutcher

On 3/17/15 12:49 PM, Jarmo.Venalainen at schneider-electric.com wrote:
Hi: 

Please be careful when working with solar system size Lithium packs on the 
cell level. 

We have been doing on-going testing with Lion battery packs from various 
suppliers and even with their built in temp sensors and other BMS 
circuits, have already had two "thermal events". 

Lion is very unforgiving with regards low state of charge, high state of 
charge, temperature (110F is the max temp at which they should be charged 
and 140F is the max they can handle). 

Given the low thermal mass of Lion cells, a high rate of discharge or 
charge quickly gets the cell temperature into the 110F+ range. 

As soon as you cross the line things start happening and if the BMS 
doesn't put a stop to it by turning the battery pack off, it's a very 
quick slide down the hill from there. 

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 

*** Please consider the environment before printing this e-mail

From: 
Larry <larry at starlightsolar.com> 
To: 
RE-wrenches <re-wrenches at lists.re-wrenches.org>, 
Date: 
03/17/2015 11:41 AM 
Subject: 
[RE-wrenches] Load testing Lithium battery bank 
Sent by: 
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>

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