ECET425L Lab 1: SLA Batteries
Objectives:
- Learn some basic battery terminology
- Be able to calculate battery run times given the desired DOD or depth of discharge
- Know how batteries can work in series and parallel
Parts List:
- 12 volt 5Ah SLA battery
- Power Resistor
- SLA-VRLA Documents in Doc Sharing
- 12v 5Ah SLA Spec sheet in Doc Sharing
- G4 LED Array
Introduction:
Sealed Lead Acid (SLA) batteries or valve regulated lead acid (VRLA) have been used for over forty years. They are one of the most economical batteries to use. They are used in mobility (wheelchairs), backup power (alarm systems) and in many solar applications. The basic principles of batteries can be used for multiple chemistries.
Step 1: Battery Definitions
Define the following:
DOD (Depth of Discharge)
Capacity
Battery Cycle
Battery Cycle Life
SOC (State of Charge)
Puekert Effect
Cyclic Battery Applications (wheelchair)
Standby Battery Applications (alarm)
Step 2: Questions about the SLA Battery Spec Sheet (45565)
Note: A 5 amp-hour battery does not mean the battery will output a current of 5 amps for one hour. Standard SLA capacities are measured at C/20 with C being the amp-hour rating of the battery.
1. At what current will the battery have a capacity of 5 amp hours?
2. At a current of 3 amps what is the run time and the capacity?
3. What is the maximum charging current for the battery?
4. What is the maximum charging voltage for the battery?
5. How many cycles can we get at a 100% DOD?
6. How many cycles can we get at a 50% DOD?
7. How many cycles can we get at a 30% DOD?
8. At a temperature of 0 degrees F what is the capacity at C/10 or .1C?
Step 3: Procedure
1. Measure the battery voltage and from this voltage state the battery capacity. Use the open circuit voltage vs. the residual capacity graph on the second page of the spec sheet.
2. Connect the 30 ohm resistor and the G4 LED lamp across the battery and measure the current through each one.
3. State how long the resistor and the G4 LED would operate at a 100% DOD and a 50% DOD.
Step 4: Calculations and Series Parallel Connections
1. A 48VDC, 120VAC 60 hertz inverter would require how many 6 volt batteries in series to operate it?
2. A typical 4000 watt sine wave inverter would require how much current from a 12 volt battery at full output power? Assume 100% efficiency. Remember Power=Voltage*Current
3. If two 12 volt 100 amp-hour batteries are used.
What is the voltage and capacity if the batteries are in parallel?
What is the voltage and capacity if the batteries are in series?