Gameplay Guide - Rjoande/RealBattery GitHub Wiki

This page explains how RealBattery Recharged changes the way electricity works in Kerbal Space Program. It covers the main gameplay mechanics: how batteries store and release energy, how heat, efficiency, and wear affect performance, and what makes each battery type unique. Whether you’re managing a probe on the dark side of the Mun or a base on Duna, understanding these systems will help you plan reliable and efficient power setups for every mission.

Each battery stores two resources: Electric Charge (EC) and Stored Charge (SC), and their amount depends on the battery's chemistry and size. Electric Charge now acts as an electrical power buffer: it's the energy pool that ship systems (like lights or converters) draw from or refill (such as generators or solar panels). You can think of EC as the ship's available power output or operating voltage. Stored Charge, on the other hand, represents the actual stored energy, which can’t be accessed directly by other parts and must be converted into EC. Batteries will try to keep the vessel’s total EC buffer above 90% by drawing from their SC reserves at a rate of 1 SC = 3600 EC. When the EC buffer rises above 95%, they'll instead recharge themselves by converting EC back into SC.

🔭 For a more detailed explanation of what EC and SC represent in real-world terms, see the dedicated section.

The maximum speed at which batteries convert SC into EC (and vice versa) depends on their chemistry and size: larger batteries can convert energy faster. This rate is called the Discharge Rate, measured in EC/s, and represents the battery's power output. The maximum and minimum Discharge Rate are shown in the PAW while in the editor (VAB/SPH). This value is based on the C-rate, which measures how many full charges a battery can deliver in one hour at its rated power (see the detailed explanation on Wikipedia). In short, 1C means the battery can fully discharge in 1 hour, 0.5C in 2 hours, 2C in 30 minutes, etc. Although it's not directly displayed in-game, the C-rate is useful to compare different battery chemistries. As a general rule, with the same SC capacity, a higher C-rate means more power. However, if the vessel's total EC/s demand is lower than the combined Discharge Rate of its batteries, they'll automatically adjust their output to match the actual load. If the demand exceeds the total Discharge Rate, the EC buffer will gradually drain until it's empty.

💡 Recharge speed is generally lower than discharge speed and varies depending on the battery chemistry and its current charge level (State of Charge or SoC).
⚙️ With DynamicBatteryStorage installed, you can set a Simulation Mode in the editor to simulate charging or discharging and preview your vessel's power balance before launch.
⚠️ When activated, thermal batteries produce a fixed Discharge Rate of 6C (meaning they fully discharge in 10 minutes).

Every battery slowly loses part of its charge when left unused for a long time. This rate is shown in each subtype's tooltip and depends on the battery's chemistry.

💡 Thermal and KERBA batteries are not affected by self-discharge (see below).
⚙️ The self-discharge feature can be disabled in the Difficulty Settings menu.

Even rechargeable batteries can only be charged and discharged a limited number of times. Each subtype's tooltip shows its total life cycles, i.e. the number of full charge+discharge cycles it can sustain while maintaining acceptable performance. Every charge or discharge gradually reduces the battery's health, resulting in lower Discharge Rate, higher heat production, and reduced storage capacity (SC). Performance loss is usually minor while the battery stays within its rated cycle count; by the end of that lifespan, its health will be around 80%. Beyond that point, the battery will still function, but its degradation will accelerate rapidly.

🔋 Discharging a battery from 100% to 0% and then recharging it back to 100% counts as one cycle.
💡 Primary (non-rechargeable) batteries have only one life cycle.
⚙️ Battery wear can be disabled in the Difficulty Settings; if turned off, batteries will always stay at 100% health.

An active battery generates heat while charging or discharging. The amount of heat depends on the current Discharge Rate and the battery's chemistry. The Thermal Loss parameter, shown in each subtype's tooltip in the editor, indicates how much heat is produced per EC/s of Discharge Rate: the higher the value, the more heat the battery generates. This heat accumulates inside the part's core or, if SystemHeat is installed, it flows into the thermal loop. If the core (or loop) gets too hot, the battery will overheat and wear out faster. Once it exceeds a certain threshold (usually about 100°C above its overheat temperature), it enters thermal runaway, a state where it produces heat on its own until its health is completely depleted. All batteries include a Protection Circuit Module (PCM), which automatically shuts them down when they overheat (in Career and Science modes this must be unlocked in the tech tree). However, external heat sources can still raise battery's temperature past the safety limit, and may even trigger a runaway even while the battery is off.

⚙️ Thermal simulation can be disabled in the Difficulty Settings. You can also choose whether to use the stock heat system or SystemHeat, and whether to enable realistic runaway behavior; if disabled, batteries will simply behave as if they're suffering a very severe overheat.
💡 In the editor, use each battery’s Simulation Mode to preview heat production during charge or discharge (requires SystemHeat).
⚠️ Thermal and ZEBRA batteries are immune to runaway (and have a very good tolerance to overheat).

Engineers can greatly extend the operational lifespan of batteries. Having an engineer on board slightly increases each battery's Discharge Rate while reducing wear and heat generation. The bonus scales with the engineer's level, up to +25% at level 5. If no engineers are present, batteries instead suffer a small -5% performance penalty.

While on EVA, an engineer can also replace a battery pack. To do so, they must be within 2.5 meters of the battery, which must be turned off and cool enough (core or loop temperature below its Overheat threshold). The vessel must also have enough Spare Parts available (this resource is included in the Community Resource Pack, which is already a dependancy for RealBattery). Replacing a battery fully restores its health and charge.

⚙️ This feature can be disabled in the Difficulty Settings. It's designed to work seamlessly with DangIt!, which also allows EVA repairs using Spare Parts and provides certain parts (like command modules) with a small internal supply of them.
⚠️ Thermal and Hafnium batteries cannot be replaced.

In flight, the PAW displays several useful details about the selected battery, such as its charge level and health status. In Career and Science modes, most of these readouts must be unlocked through the corresponding upgrades in the tech tree.

By default, all batteries are connected and ready when you launch. If you want to save a battery for a specific phase of the mission, you can disable it and reconnect it later by clicking the dedicated toggle in the PAW (both in the editor and in flight) or by assigning it to an action group. You can also link a battery's activation to a staging event (in editor only).

⚠️ Thermal batteries start deactivated by default. Once turned on, they cannot be switched off again.

Thermal batteries are found only in certain avionics parts or probe cores. By default, they are inactive in the editor and at launch, and it's best to link their activation to a staging event. Once turned on, they cannot be switched off and will provide a constant discharge until depleted (they work somewhat like SRBs). Just like their real-world counterparts, they're designed to power launch vehicles or reentry probes that need a lot of energy for a short time. They generate significant heat, but are immune to runaway.

💡 For longer operations, you can use multiple thermal batteries with staggered activation.

These batteries, slightly less powerful than lithium ones, have the unique advantage of never losing charge while idle and being completely immune to thermal runaway. However, when activated, they require a short warm-up period before becoming operational and must then be kept at temperature. To heat up and stay active, KERBA batteries consume an amount of EC equal to 5% of their Discharge Rate. If the core (or SystemHeat loop) temperature rises above 600 K, they no longer need EC to stay warm. If the temperature drops below 500 K and no EC is available, the battery will begin a shutdown sequence. When turned off manually, it stops requiring EC or heat, but you must wait for the shutdown process to complete before turning it back on.

💡 Because they can use heat alone to stay active, KERBA batteries work especially well when connected to systems that produce a lot of heat, such as ISRU units.

Hafnium batteries (Hf-178m2) are expensive, high-end cells which store an extraordinary amount of energy in a very small mass, making them ideal for compact, high-demand systems or long-duration missions where recharging isn't possible. They slowly release this energy through controlled nuclear isomer decay, providing consistent power output for months or even years. However, they are non-rechargeable and cannot be replaced during EVA: once depleted, the cell becomes inert. Hafnium cells also carry a low but non-zero risk of a spontaneous R.I.P. (Radiation-Induced Pulse) event, causing a self-runaway that rapidly releases all remaining energy as heat.

⚙️ Hourly chance of self-runaway can be adjusted in the Difficulty Settings. Set '0' do disable this feature.