The modern term "battery" refers to an electrochemical cell, which generates an electrical potential through the migration of ions through an electrolyte. In the future, the term battery may become generic to refer to other methods of electrical storage. Here, we use the term to refer to electrical energy storage devices that take significantly longer than a few seconds to charge or discharge.
The batteries listed here are all rechargeable. They can be recharged as rapdily as they can be discharged, if enough power is available. For example, a power supply that can give 2.5 kJ every second can be recharged at a rate of 2.5 kJ every second, if a source of electrical power that can deliver 2.5 kW can be found. Batteries typically need the correct voltage to recharge, which typically requires a specific rectifier and transformer to recharge off of wall power.
At TL 8, alkaline, lead-acid, and nickel-cadmium batteries can still be found, but they are gradually phased out in favor of lithium-ion batteries. Battery technology advances very rapidly in TL 8, driven at first by the demand for portable electronics that last longer between recharging, and then for electric vehicles. The batteries listed are for Li-ion batteries around 2013; it would be appropriate to halve the available energy at early TL 8 and, if current trends continue, to at least double the energy and power at late TL 8. Lab prototypes can easily reach three or four times the stored energy listed here with higher powers - this technology may be on the market in a few years.
TL 9 batteries are likely to be lithium-sulfur, lithium-air, or sodium-air batteries. They have significantly more energy and somewhat more power than modern batteries.
At TL 10, we have no idea what might be used for battery technology. Here, it is assumed that TL 10 batteries are approaching the physical limit of chemical bonds to store and release energy. Consequently, battery technology will stall at TL 10 unless nuclear or exotic physics is used.
A hypothetical TL 11 nuclear battery technology is given. These batteries can put out power for decades, their energy is nearly unlimited by they are limited by their power output. Assume that their power drops to 3/4 the listed power after 30 years, and 1/2 the listed power after 60 years (this progression continues, so that they are at 1/4 power after 120 years, 1/8 power after 180 years, and so on).
Batteries
| TL | Description | Energy (kJ) | Power (kW) | Mass (kg) | Cost | LC | Notes |
| 8 | Battery power supply | 10000 | 2.5 | 10 | $3000 | 5 | |
| 8 | Battery pack | 1000 | 0.25 | 1 | $300 | 5 | |
| 8 | Laptop battery | 500 | 0.125 | 0.5 | $150 | 5 | |
| 8 | Phone battery | 64 | 0.016 | 0.04 | $12 | 5 | |
| 8 | Flashlight battery | 16 | 0.004 | 0.016 | $5 | 5 | |
| 8 | Button battery | 2 | 0.0005 | 0.002 | $6/10 | 5 | |
| 9 | Battery power supply | 100,000 | 10 | 10 | $1000 | 5 | |
| 9 | Battery pack | 10,000 | 1 | 1 | $100 | 5 | |
| 9 | Electronics battery | 160 | 0.016 | 0.016 | $1.5 | 5 | |
| 9 | Button battery | 20 | 0.002 | 0.002 | $2/10 | 5 | |
| 10 | Battery power supply | 400,000 | 40 | 10 | $1000 | 5 | |
| 10 | Battery pack | 40,000 | 4 | 1 | $100 | 5 | |
| 10 | Electronics battery | 640 | 0.064 | 0.016 | $1.5 | 5 | |
| 10 | Button battery | 80 | 0.008 | 0.002 | $2/10 | 5 | |
| 11 | Nuclear battery power supply | unlimited | 10 | 10 | $1000 | 3 | |
| 11 | Nuclear battery pack | unlimited | 1 | 1 | $100 | 3 | |
| 11 | Nuclear electronics battery | unlimited | 0.016 | 0.016 | $1.5 | 3 | |
| 11 | Nuclear button battery | unlimited | 0.002 | 0.002 | $2/10 | 3 |
The term power cell refers to an electrical energy storage device that can charge and discharge nearly instantly. In practical terms, all of its stored energy is avaialable for use in any given turn. Power cells are typically used to deliver energy to equipment that has very high transient power needs. A typical application of interest in a game is to power directed energy weapons such as lasers.
At TL 8, power cells are electric double-layer capacitors, also called supercapacitors or ultracapacitors. Supercapacitor technology has been advancing rapidly across TL 8; those listed here are appropriate for commercially available products around the year 2013. Early TL 8 supercapacitors could store significantly less energy than thse listed, and lab prototypes have been demonstrated that could lead to a large jump in available stored energy. TL 8 supercapacitors have relatively large leakage currents, discharging over a time scale of weeks.
TL 9 power cells are assumed to be the most promising TL 8 lab prototype supercapacitors, evolved to a mature technology with lower leakage currents for longer shelf-life and on-board power regulating electronics.
The power cell technology at TL 10 and beyond is too far in the future to be reliably predicted. Possibilities include room temperature superconductors storing a persistent supercurrent in a toroidal solenoid; fast-discharge nano-electrochemical batteries; nanoscale coiled springs driving/driven by nanoscale electrical generators/motors; or flywheels in a gimballed mount attached to an electrical generator/motor. By TL 12, it is assumed that power cells have reached the physical limit of chemical bonds to store energy.
Power Cells
| TL | Description | Energy (kJ) | Power (kW) | Mass (kg) | Cost | LC | Notes |
| 8 early | Early Ultracapacitor | 15 | 15 | 1 | $1000 | 5 | |
| 8 mid | Basic Ultracapcitor | 100 | 100 | 1 | $300 | 5 | |
| 8 late | Advanced Ultracapacitor | 300 | 300 | 1 | $50 | 5 | |
| 9 | Ultracapacitor | 1000 | 1000 | 1 | $50 | 5 | |
| 10 | Power Supply | 500,000 | 500,000 | 100 | $5,000 | 5 | |
| 10 | Power Supply | 50,000 | 50,000 | 10 | $500 | 5 | |
| 10 | Power Pack | 10000 | 10000 | 2 | $100 | 5 | |
| 10 | Power Pack | 5000 | 5000 | 1 | $50 | 5 | |
| 10 | Power Pack | 1000 | 1000 | 0.2 | $10 | 5 | |
| 10 | Power Stick | 100 | 100 | 0.02 | $1 | 5 | |
| 10 | Power Button | 10 | 10 | 0.002 | $1/10 | 5 | |
| 10 | Power Grain | 1 | 1 | 0.0002 | $1/100 | 5 | |
| 11 | Power Cell | 15000 | 15000 | 1 | $5 | 5 | |
| 12 | Power Cell | 40000 | 40000 | 1 | $5 | 5 |