For decades, users had to choose either lead-acid or Ni-Cd batteries to start emergency generators (gensets). Both technologies offer complementary strengths and weaknesses. Lead-acid batteries are cheap, readily available and relatively small in size, but suffer short lives (2.5 years on average in gensets), and can fail without warning.
Ni-Cd batteries are very long-lived, typically fail gradually and are very abuse-tolerant. Unfortunately, they are expensive, consume a lot of space, and are not readily available should a replacement be needed in a hurry. They typically cannot be shipped by airfreight when expedited replacement is required.
The supercapacitor is a relatively new technology that delivers tremendous power (high discharge rate) and can perform nearly unlimited charge/discharge cycles. These properties make supercapacitors nearly ideal for starting engines under normal circumstances, such as stop/start cycling of a vehicle. Supercapacitors are also used successfully to start gensets that do not need much cranking time. Unfortunately, supercapacitors do not store much energy, meaning that they are not economically viable to use in genset applications where minimum cranking duration of 45 seconds or longer is specified by code or end-user preference. Supercapacitors can be shipped by air.
Lightweight and compact lithium batteries are used in some engine-starting applications, such as military vehicles and some cars, but engine-starting lithium batteries are not widely available yet. They also cannot be transported by air, meaning that expedited replacement is not practical.
All the batteries listed above contain hazardous materials, meaning that they must be recycled at specialized facilities. This is straightforward for lead-acid batteries, but more difficult for Ni-Cd and lithium batteries.
A new type of high discharge rate battery has been perfected in recent years. Ideal for starting gensets, the battery is more compact than lead-acid, nearly as long-lived as Ni-Cd, costs much less than Ni-Cd, contains no hazardous materials and can be shipped without restriction by air.
Watch this space and upcoming SENS e-newsletters for more information on this exciting development!