Why Our Batteries Are Better
My Experience with Shoddy Battery Factories
About 10 years ago I
read an article written by a man from the USA who was in China on a business
trip that was unrelated to batteries. He
had been contemplating buying a lithium battery pack and had been corresponding
to several candidates that proposed to sell him the batteries that he
needed. Since he had some spare time he
decided to visit some of these factories who had sent him glossy descriptions
of their abilities to supply him their batteries. What he discovered on these visits was
shocking. He said that some companies
were manufacturing batteries in small facilities no bigger than garages while
squatting on the floor with only basic tools.
There was no quality control testing.
Fortunately most of the industry has made great progress since those
early days.
When I went into the
lithium battery business in 2008, and in spite of this advance warning, I felt
that I could determine who was a legitimate supplier and who were fraudulent or
made poor quality cells. It turned out
that even with my best efforts to evaluate the Chinese lithium battery
suppliers I still had some experiences that cost our company a loss in
reputation and a large amount of money.
Finally I decided that the only way I could really evaluate some of the
companies that made us some good offers was to go to China and do plant surveys. It was an eye opening experience. As a result I now routinely go to China to
try to stay abreast of the latest technology and most advanced manufacturing
techniques. I try to visit up to 5
factories on each trip. These China trips have paid off because we now
know about many companies that might have caused us pain. There are literally hundreds of companies who
make lithium batteries. Eventually the
market cannot support them all and there will be a winnowing out of their ranks
and only the efficient will succeed. As
they struggle and in their desperate effort to survive they are tempted to
lower the purity of the chemicals in their cells and take other shortcuts in an
effort to lower prices and stay competitive.
Great New Battery Factory Discovered – Bright Star
I am happy to report
that I feel we have finally reached my goal of representing the Bright Star Company. The reason I like the Bright Star batteries
are myriad. Here is what you should
know.
Bright Star has only
been up and running for three years.
This results in a factory which has modern equipment and is totally
automated. There is a stage in the
manufacturing of lithium batteries where almost all of the older manufacturers
use a process called a ‘Glove Box’. This
is where a number of employees in a glass enclosed clean room put their hands
through sealed holes in the glass and use rubber gloves to assemble the final
stages of the battery before it is sealed up.
Bright Star has eliminated that manual process with fully automated
equipment. Please click
here for pictures and you will
get a good idea about the quality of their cells. It is important that you know that these
pictures were taken during a normal production day and that the factory was not
all cleaned up for our visit.
Quality Control on Each Cell
Every cell undergoes a
number of tests before it is finally cleared for shipment. The results of all of these tests are sent,
in English, along with the cells to the end user. These tests include internal impedance,
capacity and matching. The cells are all
shipped in United Nations 38.3 approved packaging.
Construction Made of Thin Sheets of Copper and
Aluminum
It is important for you
to understand the cells construction to get the maximum benefits from your
investment in a lithium battery pack.
Lithium batteries can be configured into all sorts of shapes but the
basic components of these different packs is made up of either cylindrical
cells, pouch cells, or prismatic cells.
All lithium batteries are essentially the same on the inside. Lithium batteries are comprised of very thin
sheets of copper and aluminum with a chemical composition of lithium and other
chemicals like iron and phosphate which are subjected to high temperatures in
an oven and essentially fused into the copper and aluminum carriers. These copper and metal sheets are then
stacked with an electrically porous insulating material between each
sheet. Most lithium battery manufacturers
use an inexpensive paper like insulation that can catch on fire when subjected
to high temperature which can occur under heavy electrical loads. A few more advanced companies use a ceramic
insulation that will not burn. Our
company will only sell the ceramic insulated batteries to the Original
Equipment Manufacturers (OEM).
Aluminum Encased Cells have Longer Life than Plastic
Encased Cells
Prismatic Cells can be
encased in plastic or aluminum. Many
companies who started in the business of building lithium batteries started off
using batteries that were bricklike in shape and were encased in plastic. Their equipment is based upon manufacturing
the cells with a plastic case. More
recently it has been determined that a prismatic cell that is encased in an
aluminum package will have a much longer life than a cell made with a plastic
case. The reason for the longer life
lies in the fact that when batteries are charged or discharged they create
heat. The larger the ampere hour (Ah)
capacity of lithium cell the thicker the stack of aluminum and copper
plates. This heat can be detrimental to
the life of the battery if it cannot be transferred from the core of the
stack. Since plastic is a poor thermal
conductor it tends to keep the heat inside the cell. An aluminum encased cell will transfer the
heat out much better because metal has a much greater ability to transfer
heat. The thickness of the stack also
plays into the life of the cell in that the higher and larger the stack is the
harder it is to get the heat out. Aluminum
encased batteries typically have
a charge cycle life of 50% to more than twice the life of a plastic encased
prismatic battery.
Chemistry – LiFePO4 or LiNCM
Lithium Iron Phosphate,
LiFePO4, is the most popular
chemistry because it seems to hit a happy medium in that it has a long life and
is relatively inexpensive. The life of
most batteries is measured in charge cycles.
Where a sealed lead acid battery may have a charge cycle life of between
350 to 600 charge cycles before it is completely dead, a plastic encased LiFePO4 battery will have a typical charge cycle
life of more than 2000 charge cycles before it has lost 20% of its energy
storage capacity and is generally ready for replacement. Aluminum encased LiFePO4 batteries can routinely
have a life of over 3000 charge cycles.
This will be explained later under ‘Battery Construction’. Bright Star batteries range in size from 60
to 400 Ah
Lithium Nickel Cobalt
and Magnesium. LiNCM is also a
popular chemistry because it has certain properties that lend it to different
applications. Slightly different
variations in the basic LiNCM chemistry are generally referred to as ‘Polymer’
batteries. LiNCM batteries are up to 30%
lighter in weight and will generally cost up to 15% less than an equivalent
LiFePO4 battery. However they have a
shorter life. LiNCM batteries charge
cycle life can vary between 900 and 1400 charge cycles before they are
considered ready for replacement. Many
applications don’t require a long life but benefit from a higher energy
density. In these applications, such as
the battery to propel a torpedo motor, the LiNCM chemistry is perfect. We proudly represent Bestgo
Power in the English
speaking world. They manufacture the
LiNCM pouch packs for customers who need the properties of LiNCM.
Reliability of Smaller Ampere Hour (Ah) Cells
In large energy storage
applications the temptation is to use a larger ampere hour ‘Ah’ cell. That may not be the best solution. As an example if a person determines that he
needs a 12 volt 400 Ah pack he can purchase four each 3.2 volt 400 Ah batteries
and wire them in series to get 12.8 volts which happens to be the exact nominal
voltage of most 12 volt lead acid batteries.
That will give him the voltage and power that his application
requires. But, if one of those four
cells ever got weak or failed your whole pack would either get weaker or
completely fail. There is a different
approach which has gained wide recognition as a better way to accomplish the
same thing. Instead of using 4 each 400
Ah cells I would suggest that he could take 4 each 100 Ah cells and connect
them in series to get 12.8 volts and 100 Ah.
Then if you were to connect three more series strings together that were
also 12.8 volts and 100 Ah and wire them together into a parallel matrix you
would come out with the same 12.8 volts and 400 Ah. Only now if one of the cells in this matrix
pack ever got weak or failed you would lose 25% of your run time but your
voltage will still be at 12.8 volts so that your load will see the voltage it
requires to run properly. So your
reliability will go up with a percentage of the series strings placed in the
matrix.
Cost and Shipping Options
Because the factories
mentioned above are highly automated, their pricing is very competitive. If you need LiFePO4 batteries in a short
delivery time your cost will be about $1.34 per Ah when shipped by air freight
to your address. If you can wait for
about 8 weeks your cost for ocean shipping will be about $1.20 per Ah, FOB Long
Beach port of entry. The factories will
assemble your battery pack requirements into metal boxes along with an appropriate
sized BMS system all for a slightly higher price.
LiNCM packs manufactured by Bestgo will cost less per Ah.