As you may be well aware Battery storage is becoming a major part of our industry. So to help clarify some things Gary Piper from Battery Energy Power Solutions has given some battery tips to help you understand more about this technology. Gary is a committee member of SEIA Vic and has a wealth of knowledge in battery technology.
Apples Aren’t Apples
The first point I want to make is that Apples aren’t Apples when comparing Lead Acid Batteries and there are a number of types to consider:
- Lead Acid/Wet Lead Acid – Liquid Electrolyte, Tubular Positive or Flat Plate, Vented and housed in a Transparent or Non-Transparent Container. Also referred to as Wets
- GEL – Immobilised Electrolyte made of Thixotropic Gel. Valve Regulated design
- AGM – Immobilised Electrolyte stored in the Fibreglass Mat Separators
- VRLA – Valve Regulated Lead Acid. Includes both GEL and AGM battery types
Warranty
Always pay close attention to the warranty statement document as provided by the manufacturer/supplier of the particular brand of batteries you use and ensure that you comply with these terms.
Temperature Compensated Voltage (TCV)
This is the voltage adjustment that can be programmed into your battery charger to automatically adjust the charging voltage output in relationship to the temperature of the battery. The voltage will be increased at Lower Temperature and decreased at Higher Temperature. Typically it is an adjustment of Millivolts per °degree per cell. You need to refer to the Manufacturer’s Specification for the correct voltage. Beware that some battery manufacturers may not require any adjustment between a specified temperature range.
Battery Sizing
Takes into account the System Voltage Window, Load, Autonomy, Temperature, Aging Factors, Discharge Rate, Depth of Discharge and required Service Life.
Storage
If a battery is to be stored for any particular length of time then you need to be aware of what the self-discharge rates are for battery type/manufacturer that you have. Not all batteries self-discharge at the same rate. There may be a requirement for a Commissioning Charge prior to placing the battery into service.
Battery Life
Batteries have a number of Battery Life Type Statements
- Design Life – Is not a guaranteed life expectancy of a battery. It is typically a specification that would take into account Float Voltage, Maximum Discharge Rate, Number of discharges, End Voltage Limit, Ripple Current Allowed, Depth of Discharge etc. Typically you will see a Design Life stated as XX Years on Float at XX Degrees Temperature. Design Life may be achieved in a strict environmentally controlled environment.
- Cycle Life – This is the amount of Discharge/Charge Cycles you would expect to achieve at a given Temperature and Depth of Discharge. See also Service Life.
- Service Life – Approximately how long a battery of a given Design Life will actually last in a site-specific application. Basically, the actual life achieved for a specific site and service conditions.
I hope this helps.
Gary Piper