The Last Caretaker ToolsUnofficial fan toolkit
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Guides

Combat

The Last Caretaker Backpacks: Every ONi Battery and Petrol Backpack Compared

The Last Caretaker has six backpacks, all ONi models. SparkCell, VoltPlus and MegaCell store electricity; FuelLite, PetroFlow and PetroMax store petrol. They unlock from Tier 5 to Tier 16 and weigh 5 to 10 kg. Update 6 adds a new backpack for carrying items on your back.

All Six Backpacks Compared

Within each type, a later backpack unlocks at a higher tier, weighs more and needs more advanced parts. Plan the unlocks in the Skill Planner.

Stored resource, unlock tier, weight, recipe and capacity status of each backpack
BackpackStoresUnlock tierWeightRecipeCapacity
ONi SparkCellElectricityTier 55 kg
  • 1 Battery Cell
  • 1 Alloy Frame
  • 1 Connector Ports
Not confirmed yet
ONi VoltPlusElectricityTier 117.5 kg
  • Battery Cell (sources differ: 1 on the wiki, 2 in the game 0.8.5 item data)
  • 1 Alloy Frame
  • 1 Connector Ports
  • 1 Logic Chip
Not confirmed yet
ONi MegaCellElectricityTier 1510 kg
  • Battery Cell (sources differ: 1 on the wiki, 3 in the game 0.8.5 item data)
  • 1 Alloy Frame
  • 1 Connector Ports
  • 1 Logic Chip
  • 1 Power Core
Not confirmed yet
ONi FuelLitePetrolTier 75 kg
  • 1 Storage Cylinder
  • 1 Alloy Frame
  • 1 Connector Ports
Not confirmed yet
ONi PetroFlowPetrolTier 107.5 kg
  • 2 Storage Cylinder
  • 1 Alloy Frame
  • 1 Connector Ports
  • 1 Cooling Radiator
Not confirmed yet
ONi PetroMaxPetrolTier 1610 kg
  • 3 Storage Cylinder
  • 1 Alloy Frame
  • 1 Connector Ports
  • 1 Cooling System
  • 1 Cooling Radiator
  • 1 Power Core
Not confirmed yet

Where two readings disagree, both values are shown.

Which Backpack for Which Weapon

Electric weapons do not take ammunition: with the weapon held, press F to pull out its cable and connect it to a power source such as a deck supply or a powered backpack. Flame weapons refill petrol through their hose, and a recorded refill connects one to a petrol backpack. So a battery backpack (ONi SparkCell, ONi VoltPlus, ONi MegaCell) keeps electric weapons charged, and a petrol backpack (ONi FuelLite, ONi PetroFlow, ONi PetroMax) keeps flame weapons fueled.

Details in the combat guide: how to charge and refuel weapons.

Capacities: Not confirmed yet

The community wiki is the only source for capacities so far, and it gives two different figures for SparkCell. These numbers are not used in any calculator on this site.

ONi SparkCell
200 Wh on the wiki's backpack list, 250 Wh on its SparkCell page
ONi VoltPlus
500 Wh
ONi MegaCell
1,000 Wh
ONi FuelLite
100 L
ONi PetroFlow
200 L
ONi PetroMax
400 L

The New Update 6 Backpack

Channel37's October 1 preview for Update 6 shows a new backpack that lets you attach items to your back, such as a large barrel, and climb ladders while carrying one.

The preview does not show its capacity or recipe, and the October 19, 2026 release notes do not name a new backpack. They do say that anything stowed on your back now adds to your carry weight, that you must stand closer to stow things and that Felis units can be stowed too.

See everything Update 6 adds on the update tracker.

Backpack FAQ

What is the best backpack in The Last Caretaker?

It depends on what you carry. SparkCell, VoltPlus and MegaCell store electricity for electric weapons; FuelLite, PetroFlow and PetroMax store petrol for flame weapons. Each later backpack unlocks at a higher tier and weighs more, from 5 kg to 10 kg. Their capacities are not confirmed yet, so we do not rank them.

How many backpacks are there?

Six, all ONi models: three store electricity and three store petrol. The community wiki and the game 0.8.5 item data list the same six.

Is there a diesel backpack?

No. The six backpacks store either electricity or petrol. The fuel backpacks, FuelLite, PetroFlow and PetroMax, hold petrol.

How do I charge an electric weapon from a backpack?

Hold the weapon, press F to pull out its cable and connect it to a powered backpack or another power source, such as a deck supply. The weapon's rear display shows its charge from 000 to 100.

How do I get my first backpack?

Craft it. ONi SparkCell is the first, unlocked at Tier 5, and is made from a Battery Cell, an Alloy Frame and Connector Ports. The first petrol backpack, ONi FuelLite, unlocks at Tier 7.

What is the new Update 6 backpack?

In Channel37's October 1 preview for Update 6, a new backpack lets you attach items to your back, such as a large barrel, and climb ladders while carrying one. Channel37 has not shown its capacity or recipe.

Official sources and wiki

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Weapons, Sharks & Angels Guide

Compare underwater weapons, charging and ammo, then check enemy tactics.

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Related guides

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Fuel

Oil, Methane, CO2 & Fuel Guide

Where to get oil, how to make methane and CO2, how to refine fuel, and why a machine may stop producing.

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Skills

Skill Tree Planner & Calculator

Look up blueprint unlock tiers and see what your level unlocks next.

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Updates

Update 6 Release Date & Changes

Update 6 The Jump came out on October 19: what it adds, the patch notes in plain words and the official roadmap to 1.0.