Unstable power cell

An unstable power cell is a power generation unit that is of Mechanoid origin. The cell has a constant output of 400W and can be placed anywhere, but if damaged can cause a massive explosion. The cell bears some similarities to the Vanometric power cell in that it will create free energy infinitely and can be placed in fortified positions.

Acquisition

The UPC can be claimed and stolen from mechanoid clusters, once the cluster is defeated.

Beware of mechanoid turret explosions damaging the UPC, resulting in a chain explosion that can easily kill nearby colonists. Their presence presents a strategic choice; detonate the power cells from a distance to make the cluster easier to defeat, or carefully deal with the mechanoids to claim the cells for use in your base.

Summary

Unstable power cells output a continuous 400W of power without fuel or any other dependence. Only an event that stops all electric devices, like a solar flare, can interrupt this item. They glow with a radius of 4.

When damaged below 50% of their HP, they have a chance to begin to "sizzle", after 240 ticks (4 secs) they will explode. It's possible to uninstall them during "sizzle", but they still will explode on reinstallation. They also always explode on destruction, but not deconstruction. The explosion has a radius of 9.9 tiles and does 50 Bomb damage. Bomb damage is multiplied 8x against walls, 4x against other impassable structures and plants, and 2x against passable buildings.

Like all mech cluster buildings, they not only have a Flammability of 0%, but also take no damage from attacks with the Flame damage type. This is in contrast to, for example, a stone wall which will not be ignited by molotov cocktails but will take the 10 flame damage from the initial attack.

Analysis

As bomb damage is very effective against structures, an exploding unstable power cell is very effective against the mech clusters they generate with. Successfully retrieving a power cell can sometimes be difficult, and should be weighed against its explosion, but is usually worth it.

While cells only give a modest 400 W, they are fairly useful for power. They are mobile, maintenance free, and perfectly consistent. For example, a single cell can power 2 isolated deep drills, without the need to run a long power conduit line. They are also helpful as "free" power, as a supplement to your main grid. Over the life of a colony, many cells can be accrued. Deconstructing one is almost never worth it, due to the pitiful yield.

While their explosive nature can be concerning, it is manageable. If you fully surround the cell with walls, then it will be practically safe:

A single explosion cannot damage tiles beyond walls, even if the wall is destroyed. This means your other objects are safe if the cell is walled in.
- If you use walls made of sandstone blocks or stronger, then the walls will prevent any damage from an initial explosion, such as a mortar strike, and the resulting cell explosion.
As mechanoid buildings, they are completely immune to fires and short circuits.
Most raiders will not try to break walls if any other target is available.
- For sappers and breachers, place cells (remember the walls!) in an internal position, so they have to break your outside walls first.

Therefore, the only real risk comes from an unlucky mortar strike, which is able to destroy most things, anyway. For bases with overhead mountain, even this problem is resolved.

Acquisition strategies

The primary risks to cells are accidentally triggering them with stray fire during combat and the explosions that can result from destroying turrets. Several methods can be used to safely acquire power cells from mechanoid clusters:

The simplest strategy might be simply clearing the cluster. If the unstable power cells are far enough away from turrets, you may be able to recover the cell by luring mechanoids away from the cluster, and then avoiding explosive weapons and not causing more damage than needed while you destroy buildings.
Smoke launchers can be used to give colonists cover while you construct a wall around a power cell to protect it.
The Wallraise psycast can be used to surround turrets or cells to contain explosions or protect cells from stray bullets.
High-quality breach axes and pawns with improved melee damage can destroy turrets in one hit, preventing the low-health explosion. Keep in mind that this is not perfectly reliable when dealing with predamaged turrets as they may hit the target with the weaker, handle attacks instead of the devastatingly effective head attack, and this may drop them below the threshold for low-health explosions. Always check the turret's HP before and while attempting this strategy, including if the first several swings do not successfully destroy a previously full health turret.
Frag grenades destroy turrets in one hit, preventing the low-health explosion. Frag grenades have a forced miss radius of 1.9 tiles, which means directly targeting a turret may lead to a grenade landing anywhere in a radius around the target, potentially hitting nearby UPCs. If this is possible, aim the frag grenade throws slightly away from both the turret and the cell so that you destroy the turret with a grenade that flies off-target. Destroying turrets this way takes many attempted throws. Smoke launchers can again be used to give your colonists cover from the turrets while you work.