The ARB-LP21 external battery case for the Fenix HM75R and Fenix HM75R Topaz headlamps will significantly extend the lighting time. But it also works as a power bank for charging other USB electronics such as mobile phones, headphones, GPS navigation, watch, etc.

Battery case is designed for 21700 type battery (5000 mAh battery included). The case has a metal clasp, which is used for attaching to the strap holder of the HM75R headlamp, but can also be easily attached to a belt, backpack strap or trouser or jacket pocket or hide it under clothing to avoid excessive hypothermia of the battery in the winter. The headlamp connects to the case with a USB-C cable, which is equipped with lock against ripping out the cable, and can also be used to power other electronics (in which, however, it does not lock). Any other universal USB-C cable can also be used.

Fenix HM75R power extender specifications

• Powerbank functions with support for fast charging protocols PD3.0/PD2.0, QC3.0/QC2.0, FCP, SFCP, PE2.0/PE1.1.
• Uses Li-ion battery type 21700 with 5000 mAh capacity (included).
• Charges via waterproof USB-C connector.
• Made of durable aircraft aluminum.
• Resistant to drops from a height of 2 meters.
• Battery case/powerbank dimensions: 10.8 cm x 2.8 cm x 2.8 cm.
• Weight 134 grams (including battery).
• Waterproof and dustproof to IP68 standard (submersion to 2 meters for 30 minutes).
• Includes the case with buckle, USB-C cable with locks, Li-ion 21700 battery with 5000 mAh capacity, hooks to attach the cable to the strap and a spare o-ring.
• The case can optionally be purchased with a USB-C cable with locks, 1.5 meters long for carrying in a backpack, pocket and on a belt. Alternatively, a spare battery case strap holder (identical to the HM71R headlamp holder).

Using the HM75R power extender

There may be an insulating cap on the battery pack from the factory. Remove it before first use.

Lock the supplied USB-C cable in the connectors - A USB-C cable is included to connect the headlamp and battery case. The cable is equipped with locks on both ends to prevent accidental removal from the headlamp or battery case. To lock the cable, plug the USB-C cable into the connector in the headlamp and battery case and turn the cable ends clockwise. To unlock the cable, turn the cable locks counterclockwise and disconnect the cable.

Charging and powerbank functions

Charging the battery pack - Remove the dust cap and plug the USB-C charging cable into the charging port of the case. Replace the dust cap when charging is complete. During charging, the indicator in the button on the battery case lights red. When fully charged, it will light up green.

Powerbank Function - Remove the dust cap and plug the USB-C charging cable into the charging port of the case. A single press of the button on the battery case turns on the powerbank function. If the power bank is on, pressing the button again will turn it off. After replacing the battery in the battery case, the powerbank function is automatically switched on if it is connected to the headlamp. The powerbank supports the following fast charging protocols: PD3.0/PD2.0, QC3.0/QC2.0, FCP, SFCP, PE2.0/PE1.1

Powerbank Low Load Detection Function - When the powerbank function is on, hold the button on the case for 3 seconds. Turning on the low load detection function is indicated by three red flashes of the indicator LED in the button. Turning the function off is indicated by eight red flashes. This function is designed for charging USB devices with very low load, such as fitness trackers and wireless headphones. With the low-load detection feature enabled, the power bank will automatically stop discharging when the headlamp is fully charged. To restart the powerbank function, plug the USB-C cable back into it or press the button on the battery case. With the low-load detection function disabled, turn off the powerbank function by pressing the button when the headlamp is fully charged to avoid unnecessary discharge of the battery in the rear battery case.

Battery status indication when the powerbank is turned on - If the battery is sufficiently charged, the button on the case flashes green, if the battery voltage drops below 3.2V, the button flashes red. The powerbank function will automatically switch off if the battery voltage drops below 3.0 V.

Indication of the battery charge status in the battery case - If the battery case is not connected by cable to the headlamp or other USB device, the battery charge status in the case can be detected by pressing the button. If the indicator LED is green when the button is pressed, the battery is more than 85% charged. Green flashing indicates 50-85% capacity. If the light is red, the battery is 25-50% charged. Red flashing indicates less than 25% capacity remaining.

Changing batteries - Insert the battery with the plus pole facing out. If the battery case cap is not fully tightened, it will not function properly.

Warning

• Do not disassemble the sealed parts yourself, it will violate the warranty.
• Use only high quality Li-ion batteries to power the battery pack.
• If the battery case does not work properly, it may be due to one of the following reasons:
  • The battery is almost dead – replace it or charge it.
  • The contacts in the battery case are dirty – clean them with a cotton ball dipped in alcohol.

Warranty

Five years warranty on the case, two years on the battery.