High Power Batteries (More than 5Ah)
Some batteries need to be "Bomb Proof"
For low power applications such as mobile phones or power tools where the typical cost of a battery may be £10 or less, batteries are often considered as consumables and battery maintenance is not usually a high priority. But for high power Traction Applications such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) where batteries may cost thousands of pounds, maximising the Battery Life becomes a major design objective.
Battery designs may be optimised for capacity or for power handling capability, often called "rate". For example, in EV applications, range is most important and so they use high capacity batteries. HEVs on the other hand require smaller batteries which can provide a high instantaneous power boost and they use high rate batteries. The section on Cell Construction explains the design trade-offs involved.
Deep cycle batteries are designed to be discharged down to as much as 80% depth of discharge time after time, and have much thicker plates that a standard automotive battery.
Many high power batteries are also used in safety critical applications or for providing emergency power. The overriding design goal is that they should be able to deliver their specified power whenever they are called upon to do so. For this the user needs to be able to monitor the condition of the battery (known as the State of Health) at any time and to be have available tools and procedures to maintain the battery in top working condition.
In many applications high power batteries also generate excessive heat and Thermal Management also becomes a necessary design consideration. In the quest to get the maximum energy storage or maximum power delivery from practical battery installations many novel Cell Chemistries have been developed. These are almost always secondary cells, but some single use batteries have been developed for emergency or military applications.
Because of their high energy content the consequences of failure of these cells can be very dangerous. See the section on Safety for an indication of the destructive power of a shorted cell.
Safety considerations should therefore be high on the designer's priority list.
See also Low Power Batteries