FAQ

Why do you only sell CALB LiFePo4 batteries

Our 10+ years of working with LiFePo4 batteries has allowed us to evaluate many lithium battery brands. Some battery cells performed very poorly and some quite well. CALB has been there from the start and the quality of CALB cells has always been as high or higher than other manufacturers. When building battery packs with individual cells it is very important that the cells themselves have consistent charge capacity. If they do not, the BMS system will be constantly trying to balance each cell instead of simply monitoring. As a battery pack ages the cells should degrade equally but if the consistency and quality control is not good at the battery factory the whole battery pack will suffer. It is true that a battery pack is only as good as its weakest cell.

Do I need a battery management system for my battery application?

Battery management can have many meanings and can be confusing. The short answer is yes, it is a good idea to have some sort of over and under voltage protection for your valuable lithium batteries. Cell balancing is another function of a modern battery management system which is important. Cell balancing becomes more important as cells age and small differences in the capacity of each cell show up. A balancing system will keep all the cell capacities equalized so any one cell is not overcharged or over-discharged. The Orion BMS system offers more features than many battery systems require. It can be used in a simple form or can be programmed for complete control and monitoring of a battery system. There is a big difference between Lithium Phosphate batteries and cobalt-based lithium batteries. With cells based on cobalt chemistries (electric car batteries or laptop batteries), a battery management system is mandatory to safely operate the system. These cells can start on fire if they are abused by overcharging or over-discharging. Lithium phosphate batteries are the safest lithium battery type and do not start on fire when abused. For this reason, many decide not to use a battery management system. An example would be a 12v solar energy system where only 4 cells are managed. If the system has a programmable charge controller it can be set to not over-charge the cells and a programmable inverter will protect the cells from over discharge. If the cells are well balanced when they are installed they should stay well balanced for some time. Other protection can be added by charging and discharging to conservative levels.

What accessories come with the batteries?

CALB cells - CALB cells come in single 3.2 V cells. Busbars and terminal bolts are sold separately in sets (one required for each cell). Standard copper terminal wire lugs can be used to make up cables and set up a battery system. If CALB batteries are purchased to replace a lead acid battery system the terminal lugs and cables from the lead-acid system can often be re-used with CALB cells.

How should Li-ion Batteries be stored?

Our batteries have characteristics of very low self-leakage rate, ~ 3% per month, which allows batteries to be stored over an extended period of time. Batteries are to be charged to 40-60% full and disconnect all loads before long-term storage. Batteries must be stored in cool temperature environment. Avoid batteries being exposed to summer heat. Users are recommended to check cell voltages periodically, e.g. every 2 weeks, to ensure proper voltage level. If cell voltage drops close to 3.0V or under 3.0V, the battery needs to be recharged.

What can potentially damage batteries?

Over-discharging, over-charging, operating outside of the current specification limits and operating outside of the temperature specification limits are the most common ways of damaging the batteries.

During charging, not using a proper charger and no EMS monitoring and protection against over-voltage can lead to an overcharging condition.
During discharging, no EMS monitoring of cell voltages can result in cell voltages dropping below low voltage limit, which lead to the over-discharge condition.
Drawing extreme high current (>3C) over an extended period of time (>20seconds) can result in damages to the batteries.
Proper operating temperature ranges are -20 to 65C for discharging and 0 to 65C for charging. Not operating and storing batteries within these temperature ranges can result in damages to the batteries.
Mixing batteries with different characteristics, voltage ranges, capacities, internal resistance, ages, which may lead to uneven loading across batteries, can potentially result in over-charging and over-discharging conditions.
Putting batteries in parallel without EMS monitoring and control can lead to unbalanced charging and discharging conditions.

What are the best practices to maximize the lifetime of Li-ion batteries?

Cell voltages, depth of discharge, operating temperature and current draws are the key factors determining the lifetime of the batteries. Li-ion battery cells must be operating within the specified voltage range at all times. Over-charging and over-discharging will result in reduced battery life or even kill the battery.

Our batteries have no memory effect. Batteries do not need to be completely discharged before charging. In fact, reducing the depth of discharge (%DOD) can significantly increase the number of cycles. Therefore we recommend charging the batteries as often as possible instead of waiting for the batteries to be completed drained.

Operating the batteries in extreme weather conditions (extreme heat and extreme cold weathers) will shorten the battery lifetime. Having a climate control system to maintain the battery temperature around room temperature will help to prolong the battery lifetime.

High current draw during discharging and fast charging current will also reduce cycle life. Charging and discharging batteries at 0.5C will produce the best result of cycle life.

How much current can I draw from my battery pack?

Cell voltage drops with increasing current draw. In other words, cell voltages sag with high current draw. Voltage sag may become more significant when current draw is over 2C. We recommend impulse current draw to be limited to 3C and continuous current draw to be limited to 2C. Impulse current draw must be limited to 20 seconds. An extended period of high current draw (over 3C) will shorten the lifetime of batteries, and may even damage the batteries. ​

How many cells do I need to purchase for my battery pack?

Each cell has nominal voltage of 3.2V (2.5V min and 4.25V max). Based on your electric motor voltage demand, you can decide how many cells you need. If you have a 144V system, the number of cells in your battery pack will be 144V / 3.2V = 45 cells.

What cell size is most suitable for my application?

After you decide how many cells your battery pack requires, you need to decide what cell type or capacity for your application. This depends on the power consumption of our application and the desired run time. For electric vehicle applications, your driving habit strongly affects energy consumption rate (kWh/mile). Range drops with increasing speed. Under Technical Reference session of this website, you can find range vs. speed curves (EV Application Calculation). A typical small sedan consumes about 0.25 kWh of energy per mile. Based on the desired conditions for your application (vehicle weight, average speed, range, etc.), you can decide how much energy you need in your battery pack (kWh), which will then decide the capacity of your cell choice. For example, if you need 28.8kWh capacity and you have decided on a 45 cell pack based on the voltage spec of your motor, 28800 kWh / 45 cells / 3.2V per cell = 200Ah. You need cells with 200Ah capacity.

What is the recommended charging process?

Lithium chargers use constant current, constant voltage. If the charger is designed for lead acid batteries it must never go into "equalization mode". This will overcharge the lithium batteries. We recommend setting all charging sources to shut-off at 3.6V /cell max. Many of our customer using batteries for solar energy storage only charge the cells to 3.4V/cell to extend life (roughly 80%)