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.