def METHOD_NAME(show_plots):
    """
    **Validation Test Description**
    1. Whether the simpleBattery can add multiple nodes (core base class functionality);
    2. That the battery correctly evaluates how much stored power it should have given a pair of five-watt
       input messages.
    :param show_plots: Not used; no plots to be shown.
    :return:
    """
    testFailCount = 0                       # zero unit test result counter
    testMessages = []                       # create empty array to store test log messages
    unitTaskName = "unitTask"               # arbitrary name (don't change)
    unitProcessName = "TestProcess"         # arbitrary name (don't change)
    # Create a sim module as an empty container
    unitTestSim = SimulationBaseClass.SimBaseClass()
    # Create test thread
    testProcessRate = macros.sec2nano(0.1)     # update process rate update time
    testProc = unitTestSim.CreateNewProcess(unitProcessName)
    testProc.addTask(unitTestSim.CreateNewTask(unitTaskName, testProcessRate))
    test_battery = simpleBattery.SimpleBattery()
    test_battery.storedCharge_Init = 5.
    test_battery.storageCapacity = 10.  # 10 W-s capacity.
    powerMsg1 = messaging.PowerNodeUsageMsgPayload()
    powerMsg1.netPower = 5.0
    pw1Msg = messaging.PowerNodeUsageMsg().write(powerMsg1)
    powerMsg2 = messaging.PowerNodeUsageMsgPayload()
    powerMsg2.netPower = 5.0
    pw2Msg = messaging.PowerNodeUsageMsg().write(powerMsg2)
    # Test the addNodeToStorage method:
    test_battery.addPowerNodeToModel(pw1Msg)
    test_battery.addPowerNodeToModel(pw2Msg)
    unitTestSim.AddModelToTask(unitTaskName, test_battery)
    dataLog = test_battery.batPowerOutMsg.recorder()
    unitTestSim.AddModelToTask(unitTaskName, dataLog)
    unitTestSim.InitializeSimulation()
    unitTestSim.ConfigureStopTime(macros.sec2nano(5.0))
    unitTestSim.ExecuteSimulation()
    storedChargeLog = dataLog.storageLevel
    capacityLog = dataLog.storageCapacity
    netPowerLog = dataLog.currentNetPower
    #   Check 1 - is net power equal to 10.?
    for ind in range(0,len(netPowerLog)):
        currentPower = netPowerLog[ind]
        if currentPower !=10.:
            testFailCount +=1
            testMessages.append("FAILED: SimpleBattery did not correctly log the net power.")
    if not unitTestSupport.isDoubleEqualRelative((10.),storedChargeLog[-1], 1e-8):
        testFailCount+=1
        testMessages.append("FAILED: SimpleBattery did not track integrated power. Returned "+str(storedChargeLog[-1,1])+", expected "+str((10.)))
    for ind in range(0,len(storedChargeLog)):
        if storedChargeLog[ind] > capacityLog[ind]:
            testFailCount +=1
            testMessages.append("FAILED: SimpleBattery's stored charge exceeded its capacity.")
        if storedChargeLog[ind] < 0.:
            testFailCount +=1
            testMessages.append("FAILED: SimpleBattery's stored charge was negative.")
    return [testFailCount, ''.join(testMessages)]