DERELIKT Battery Puzzle Solution: Louis Hartman's APC Job
The full battery puzzle: where the lug wrench is, which APC holds the cell, how to install it and why the achievement is called 1.21 Jiggawatts.
The battery puzzle is the most searched DERELIKT puzzle, and it is also the one that most players overthink. There is no code, no sequence and no hidden panel. There is a dead APC, a living engineer, a lug wrench and a battery that has to travel between two vehicles on the same asteroid.
The confusion comes from the game's objective text, which says "find a replacement battery" without saying which APC it means. Both APCs are on the Anomaly Surface, and the game lets you walk past the one with the battery three times before it tells you.
This puzzle only appears after you finish the Anomaly Surface walkthrough→, so clear the surface section first.
What the puzzle actually is
Louis Hartman is stranded at APC Site 2 with a dead vehicle. The replacement cell is in the first APC at the landing zone, the one you passed at the start of the level. To move the cell you need the lug wrench, which is lying next to Louis.
In order:
- Talk to Louis at APC Site 2.
- Pick up the lug wrench beside him.
- Walk back to the landing zone.
- Open the first APC's battery housing with the wrench.
- Take the battery.
- Return to APC Site 2.
- Install the battery in Louis's APC.
- Talk to Louis to finish the objective.
That is the whole puzzle. The achievement 1.21 Jiggawatts (7.4%) fires on step 7, not on step 8.
Step-by-step walkthrough
Step 1: reach APC Site 2
APC Site 2 is past the derelict campsite, across the pillar jumps. You cannot reach it before you have the Assault Rifle, because the route is guarded by Proxies that the pistol cannot kill efficiently.
Louis stands beside the APC with a toolbox at his feet. His dialogue is short: the APC is dead, the cell is gone, and the other APC at the landing zone still has one.
Step 2: take the lug wrench
The lug wrench is on the ground to Louis's left, half under the APC's front wheel. It is a quest item and it goes into your grid automatically.
If the wrench is not there, you have not finished the conversation. The item spawns when Louis finishes his second dialogue page.
Step 3: walk back to the landing zone
The walk back is the long part. The route is the same one you took in, but the scripted Proxy chase is over and the enemies you killed stay dead. Two things to watch:
- The pillar jumps are one-way in the outward direction, but the return route uses the lower ledges. Follow the lights, not the jumps.
- Rock Worms respawn at the trench. Shotgun them and keep moving.
The first APC is the vehicle you walked past at the very start of the level, before the twin pillars. It is not the APC beside Louis.
Step 4: open the battery housing
Interact with the rear panel of the first APC. The prompt requires the lug wrench; without it, the game says the bolts are seized.
The housing opens to reveal the battery. Take it. Your character notes that it is heavy, which is the game's hint that the return trip is slower.
Step 5: install the battery
Back at APC Site 2, interact with the open battery bay on Louis's APC. The installation is a single prompt and a short animation.
The achievement fires here. If it does not, check that you are at the correct APC: Louis's vehicle has the open bay, the first APC has the panel you removed.
Step 6: talk to Louis
Louis thanks you, starts the APC and opens the route back to the station. The objective completes and the level's return trip unlocks.
Common problems
| Problem | Cause | Fix |
|---|---|---|
| Wrench not on the ground | Louis's dialogue not finished | Talk to him until he repeats himself |
| Battery housing will not open | Wrong APC | The battery is at the landing zone, not at Site 2 |
| Achievement did not fire | Installed before taking the quest | Reload a save and do the steps in order |
| Louis will not talk after installation | Objective flag stuck | Walk to the APC's front and back, then return |
| Battery disappeared from inventory | Grid full during pickup | Free a slot at the campsite storage box |
The grid issue is real: the battery takes a 2×1 slot, and if your grid is full the pickup can fail silently. Drop a duplicate ammo stack before you open the housing.
The Insight bridge and Shriver's Notes 6/13 are on the return path from the first APC. Grab them before you reinstall the battery, or you will walk the cliff a second time.
Why it is called 1.21 Jiggawatts
The achievement name is a Back to the Future reference, and the number is a joke about the film's 1.21 gigawatts. It has no mechanical meaning in DERELIKT; the battery is a normal quest item.
FAQ
Where is the lug wrench? On the ground beside Louis Hartman at APC Site 2, after his second dialogue page.
Which APC has the battery? The first one, at the landing zone before the twin pillars.
Do I need the Assault Rifle for this puzzle? Practically, yes. The route to APC Site 2 is guarded by Proxies.
Can I do the battery before the campsite? No. Louis is past the campsite and the route is gated by the rifle pickup.
Into Indie Games' surface walkthrough reaches APC Site 2 and Louis Hartman but stops short of the return trip, which is exactly where most players get stuck.
Sources and further reading
The pages below are the sources this guide checks against. The store page and the developer's post are primary; the reviews are secondary and are used for enemy names, weapon names and the state of the game at launch.
- DERELIKT on Steam ↗ — the store page, system requirements and the 27-achievement list.
- Visuwyg's announcement post ↗ — the developer's own description of the outpost and the PS1 rendering work.
- Into Indie Games' Anomaly Surface walkthrough ↗ — a second independent route check for the surface.
Official source: Visuwyg — DERELIKT announcement post ↗, 8 September 2025.
"grafted onto an anomalous derelict asteroid in orbit around Saturn" — Visuwyg, DERELIKT announcement post, 2025