Why Our Batteries Are Better
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
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
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.
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.
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.
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).
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
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.
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 connect 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.
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.