Whether the AC adapter is connected or not, the battery is always detected as discharging:

When AC adapter is present:

$ sudo acpitool -a -b
  Battery #1     : Discharging, 100.0%
  AC adapter     : online 

$ sudo acpitool -B
  Battery #1     : present
    Remaining capacity : 54027 mWh, 100.0%
    Design capacity    : 56041 mWh
    Last full capacity : 53507 mWh, 95.48% of design capacity
    Capacity loss      : 4.522%
    Present rate       : 0 mW
    Charging state     : Discharging
    Battery type       : Li-ion 
    Model number       : ASUS

When AC adapter is not present:

$ sudo acpitool -a -b
  Battery #1     : Discharging, 100.0%, 04:19:49
  AC adapter     : off-line 

$ sudo acpitool -B
  Battery #1     : present
    Remaining capacity : 54005 mWh, 100.0%, 04:28:31
    Design capacity    : 56041 mWh
    Last full capacity : 53507 mWh, 95.48% of design capacity
    Capacity loss      : 4.522%
    Present rate       : 12067 mW
    Charging state     : Discharging
    Battery type       : Li-ion 
    Model number       : ASUS

System information:

$ sudo dmidecode 
# dmidecode 2.12
# SMBIOS entry point at 0xace2a898
SMBIOS 2.8 present.
27 structures occupying 2154 bytes.
Table at 0xAC7C6000.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
	Vendor: American Megatrends Inc.
	Version: UX305LA.202
	Release Date: 04/16/2015
	Address: 0xF0000
	Runtime Size: 64 kB
	ROM Size: 6464 kB
	Characteristics:
		PCI is supported
		BIOS is upgradeable
		BIOS shadowing is allowed
		Boot from CD is supported
		Selectable boot is supported
		BIOS ROM is socketed
		EDD is supported
		5.25"/1.2 MB floppy services are supported (int 13h)
		3.5"/720 kB floppy services are supported (int 13h)
		3.5"/2.88 MB floppy services are supported (int 13h)
		Print screen service is supported (int 5h)
		8042 keyboard services are supported (int 9h)
		Serial services are supported (int 14h)
		Printer services are supported (int 17h)
		ACPI is supported
		USB legacy is supported
		Smart battery is supported
		BIOS boot specification is supported
		Targeted content distribution is supported
		UEFI is supported
	BIOS Revision: 5.6

Handle 0x0001, DMI type 1, 27 bytes
System Information
	Manufacturer: ASUSTeK COMPUTER INC.
	Product Name: UX305LA
	Version: 1.0       
	Serial Number: F6N0CJ005192234     
	UUID: 8ACDCACA-23D7-6D4B-8403-68B4F242E258
	Wake-up Type: Power Switch
	SKU Number: ASUS-NotebookSKU
	Family: UX

Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
	Manufacturer: ASUSTeK COMPUTER INC.
	Product Name: UX305LA
	Version: 1.0       
	Serial Number: BSN12345678901234567
	Asset Tag: ATN12345678901234567
	Features:
		Board is a hosting board
		Board is replaceable
	Location In Chassis: MIDDLE              
	Chassis Handle: 0x0003
	Type: Motherboard
	Contained Object Handles: 0

Handle 0x0003, DMI type 3, 25 bytes
Chassis Information
	Manufacturer: ASUSTeK COMPUTER INC.
	Type: Notebook
	Lock: Not Present
	Version: 1.0       
	Serial Number: F6N0CJ005192234     
	Asset Tag: ATN12345678901234567
	Boot-up State: Safe
	Power Supply State: Safe
	Thermal State: Safe
	Security Status: None
	OEM Information: 0x00000000
	Height: Unspecified
	Number Of Power Cords: 1
	Contained Elements: 1
		<OUT OF SPEC> (0)
	SKU Number: To be filled by O.E.M.

Handle 0x0004, DMI type 10, 26 bytes
On Board Device 1 Information
	Type: Video
	Status: Enabled
	Description:  VGA
On Board Device 2 Information
	Type: Ethernet
	Status: Enabled
	Description:  GLAN
On Board Device 3 Information
	Type: Ethernet
	Status: Enabled
	Description:  WLAN
On Board Device 4 Information
	Type: Sound
	Status: Enabled
	Description:  Audio CODEC 
On Board Device 5 Information
	Type: SATA Controller
	Status: Enabled
	Description:  SATA Controller
On Board Device 6 Information
	Type: Other
	Status: Enabled
	Description:  USB 2.0 Controller
On Board Device 7 Information
	Type: Other
	Status: Enabled
	Description:  USB 3.0 Controller
On Board Device 8 Information
	Type: Other
	Status: Enabled
	Description:  SMBus Controller
On Board Device 9 Information
	Type: Other
	Status: Enabled
	Description:  Card Reader
On Board Device 10 Information
	Type: Other
	Status: Enabled
	Description:  Cmos Camera
On Board Device 11 Information
	Type: Other
	Status: Enabled
	Description:  Bluetooth

Handle 0x0005, DMI type 11, 5 bytes
OEM Strings
	String 1:              
	String 2:              
	String 3:              
	String 4: 90NB08T5-M00230
	String 5:  
	String 6:  
	String 7:  
	String 8:  
	String 9:  
	String 10:  

Handle 0x000C, DMI type 32, 20 bytes
System Boot Information
	Status: No errors detected

Handle 0x000D, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L1 Cache
	Configuration: Enabled, Not Socketed, Level 1
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 32 kB
	Maximum Size: 32 kB
	Supported SRAM Types:
		Synchronous
	Installed SRAM Type: Synchronous
	Speed: Unknown
	Error Correction Type: Parity
	System Type: Data
	Associativity: 8-way Set-associative

Handle 0x000E, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L1 Cache
	Configuration: Enabled, Not Socketed, Level 1
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 32 kB
	Maximum Size: 32 kB
	Supported SRAM Types:
		Synchronous
	Installed SRAM Type: Synchronous
	Speed: Unknown
	Error Correction Type: Parity
	System Type: Instruction
	Associativity: 8-way Set-associative

Handle 0x000F, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L2 Cache
	Configuration: Enabled, Not Socketed, Level 2
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 256 kB
	Maximum Size: 256 kB
	Supported SRAM Types:
		Synchronous
	Installed SRAM Type: Synchronous
	Speed: Unknown
	Error Correction Type: Single-bit ECC
	System Type: Unified
	Associativity: 8-way Set-associative

Handle 0x0010, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L3 Cache
	Configuration: Enabled, Not Socketed, Level 3
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 4096 kB
	Maximum Size: 4096 kB
	Supported SRAM Types:
		Synchronous
	Installed SRAM Type: Synchronous
	Speed: Unknown
	Error Correction Type: Multi-bit ECC
	System Type: Unified
	Associativity: 16-way Set-associative

Handle 0x0011, DMI type 4, 42 bytes
Processor Information
	Socket Designation: SOCKET 0
	Type: Central Processor
	Family: Core i7
	Manufacturer: Intel(R) Corporation
	ID: D4 06 03 00 FF FB EB BF
	Signature: Type 0, Family 6, Model 61, Stepping 4
	Flags:
		FPU (Floating-point unit on-chip)
		VME (Virtual mode extension)
		DE (Debugging extension)
		PSE (Page size extension)
		TSC (Time stamp counter)
		MSR (Model specific registers)
		PAE (Physical address extension)
		MCE (Machine check exception)
		CX8 (CMPXCHG8 instruction supported)
		APIC (On-chip APIC hardware supported)
		SEP (Fast system call)
		MTRR (Memory type range registers)
		PGE (Page global enable)
		MCA (Machine check architecture)
		CMOV (Conditional move instruction supported)
		PAT (Page attribute table)
		PSE-36 (36-bit page size extension)
		CLFSH (CLFLUSH instruction supported)
		DS (Debug store)
		ACPI (ACPI supported)
		MMX (MMX technology supported)
		FXSR (FXSAVE and FXSTOR instructions supported)
		SSE (Streaming SIMD extensions)
		SSE2 (Streaming SIMD extensions 2)
		SS (Self-snoop)
		HTT (Multi-threading)
		TM (Thermal monitor supported)
		PBE (Pending break enabled)
	Version: Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz
	Voltage: 0.9 V
	External Clock: 100 MHz
	Max Speed: 2400 MHz
	Current Speed: 2400 MHz
	Status: Populated, Enabled
	Upgrade: <OUT OF SPEC>
	L1 Cache Handle: 0x000E
	L2 Cache Handle: 0x000F
	L3 Cache Handle: 0x0010
	Serial Number: NULL
	Asset Tag: To Be Filled By O.E.M
	Part Number: To Be Filled By O.E.M
	Core Count: 2
	Core Enabled: 2
	Thread Count: 4
	Characteristics:
		64-bit capable
		Multi-Core
		Hardware Thread
		Execute Protection
		Enhanced Virtualization
		Power/Performance Control

Handle 0x0012, DMI type 221, 12 bytes
OEM-specific Type
	Header and Data:
		DD 0C 12 00 01 01 00 02 06 00 00 00
	Strings:
		Reference Code - ACPI

Handle 0x0013, DMI type 16, 23 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: None
	Maximum Capacity: 16 GB
	Error Information Handle: Not Provided
	Number Of Devices: 2

Handle 0x0014, DMI type 17, 34 bytes
Memory Device
	Array Handle: 0x0013
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 4096 MB
	Form Factor: SODIMM
	Set: None
	Locator: ChannelA-DIMM0
	Bank Locator: BANK 0
	Type: <OUT OF SPEC>
	Type Detail: Synchronous
	Speed: 1600 MHz
	Manufacturer: 0000
	Serial Number: 00000000
	Asset Tag: 9876543210
	Part Number:                   
	Rank: 2
	Configured Clock Speed: 1600 MHz

Handle 0x0015, DMI type 17, 34 bytes
Memory Device
	Array Handle: 0x0013
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 4096 MB
	Form Factor: SODIMM
	Set: None
	Locator: ChannelB-DIMM0
	Bank Locator: BANK 2
	Type: <OUT OF SPEC>
	Type Detail: Synchronous
	Speed: 1600 MHz
	Manufacturer: 0000
	Serial Number: 00000000
	Asset Tag: 9876543210
	Part Number:                   
	Rank: 2
	Configured Clock Speed: 1600 MHz

Handle 0x0016, DMI type 19, 31 bytes
Memory Array Mapped Address
	Starting Address: 0x00000000000
	Ending Address: 0x001FFFFFFFF
	Range Size: 8 GB
	Physical Array Handle: 0x0013
	Partition Width: 2

Handle 0x0017, DMI type 20, 35 bytes
Memory Device Mapped Address
	Starting Address: 0x00000000000
	Ending Address: 0x000FFFFFFFF
	Range Size: 4 GB
	Physical Device Handle: 0x0015
	Memory Array Mapped Address Handle: 0x0016
	Partition Row Position: Unknown
	Interleave Position: 1
	Interleaved Data Depth: 1

Handle 0x0018, DMI type 20, 35 bytes
Memory Device Mapped Address
	Starting Address: 0x00100000000
	Ending Address: 0x001FFFFFFFF
	Range Size: 4 GB
	Physical Device Handle: 0x0015
	Memory Array Mapped Address Handle: 0x0016
	Partition Row Position: Unknown
	Interleave Position: 2
	Interleaved Data Depth: 1

Handle 0x0019, DMI type 221, 54 bytes
OEM-specific Type
	Header and Data:
		DD 36 19 00 07 01 00 02 06 00 00 00 02 00 02 06
		00 00 00 03 00 02 06 00 00 00 04 05 FF FF FF FF
		FF 06 00 FF FF FF 09 00 07 00 FF FF FF 09 00 08
		00 FF FF FF FF FF
	Strings:
		Reference Code - SA - System Agent
		Reference Code - MRC
		SA - PCIe Version
		SA-CRID Status
		Disabled
		SA-CRID Original Value
		SA-CRID New Value
		OPROM - VBIOS

Handle 0x001A, DMI type 221, 26 bytes
OEM-specific Type
	Header and Data:
		DD 1A 1A 00 03 01 00 02 06 00 00 00 02 00 FF FF
		FF FF 00 03 04 0A 00 26 E8 03
	Strings:
		Reference Code - ME 10.0
		MEBx version
		ME Firmware Version
		1.5MB SKU

Handle 0x001B, DMI type 221, 68 bytes
OEM-specific Type
	Header and Data:
		DD 44 1B 00 09 01 00 02 06 00 00 00 02 03 FF FF
		FF FF FF 04 00 FF FF FF 03 00 05 00 FF FF FF 03
		00 06 00 FF FF FF FF FF 07 00 19 00 00 00 00 08
		00 2C 00 00 00 00 09 00 03 00 00 00 00 0A 00 01
		00 00 00 00
	Strings:
		Reference Code - PCH - Lynxpoint
		PCH-CRID Status
		Disabled
		PCH-CRID Original Value
		PCH-CRID New Value
		OPROM - RST - RAID
		LPTLp Bx Hsio Version
		LPTH Cx Hsio Version
		PCH9S A0 Hsio Version
		WPTLp B0 Hsio Version

Handle 0x001C, DMI type 221, 26 bytes
OEM-specific Type
	Header and Data:
		DD 1A 1C 00 03 01 00 02 06 00 00 00 02 00 00 00
		00 1D 00 03 00 00 05 00 00 00
	Strings:
		Reference Code - CPU
		uCode Version
		TXT ACM version

Handle 0x001D, DMI type 13, 22 bytes
BIOS Language Information
	Language Description Format: Long
	Installable Languages: 1
		en|US|iso8859-1
	Currently Installed Language: en|US|iso8859-1

Handle 0x001E, DMI type 131, 64 bytes
OEM-specific Type
	Header and Data:
		83 40 1E 00 31 00 00 00 00 00 00 00 00 00 00 00
		F8 00 C3 9C 00 00 00 00 01 40 00 00 00 00 0A 00
		E8 03 26 00 00 00 00 00 C8 00 FF FF 00 00 00 00
		00 00 00 00 26 00 00 00 76 50 72 6F 00 00 00 00

Handle 0x001F, DMI type 14, 20 bytes
Group Associations
	Name: Firmware Version Info
	Items: 5
		0x0012 (<OUT OF SPEC>)
		0x0019 (<OUT OF SPEC>)
		0x001A (<OUT OF SPEC>)
		0x001B (<OUT OF SPEC>)
		0x001C (<OUT OF SPEC>)

Handle 0x0020, DMI type 127, 4 bytes
End Of Table