DIY Energy

The grid is fragile. In a world of increasing blackouts, failing infrastructure, and economic precarity, the ability to generate, store, and manage your own electricity is not a hobby—it's survival infrastructure. This is the knowledge they don't teach in schools because it undermines dependence on centralized utilities.

DIY energy is the art of salvaging power from waste, building batteries from scrap, and creating electricity systems that work when the grid doesn't. It's technical, dangerous, and absolutely essential.

The Physics of Electricity (Minimal Viable Understanding)

You don't need an electrical engineering degree, but you need to understand the basics:

Voltage (V): Electrical pressure. Like water pressure in a pipe. Higher voltage can push electricity farther and do more work, but also more dangerous.

Current (A or Amps): Flow rate. How much electricity is moving. High current heats wires and can start fires.

Power (W or Watts): Voltage × Current. The actual work being done. A 100W solar panel at 18V produces about 5.5 amps.

Capacity (Ah or Amp-hours): How long a battery can deliver current. A 100Ah battery can deliver 1 amp for 100 hours, or 10 amps for 10 hours.

Energy (Wh or Watt-hours): Power × Time. A 100W panel running 5 hours produces 500Wh of energy. This is what matters for sizing systems.

AC vs DC:

DC (Direct Current): Flows one direction. Batteries, solar panels, USB devices. Safer at low voltages.
AC (Alternating Current): Switches direction 60 times/second (US). Grid power. More dangerous, harder to store, but easier to transmit long distances.

Ohm's Law: V = I × R. Voltage equals current times resistance. If you know two values, you can calculate the third. This is how you size wires, fuses, and components.

Salvaging Lithium Batteries from E-Waste

The most valuable commodity in the waste stream: 18650 and 21700 lithium cells from laptop batteries, power tools, and ebike packs.

Where to Find Them

Laptop battery packs: 6-12 cells each, often only 1-2 are actually dead. Look for swollen packs (indicates cell failure) but cells inside may still be good.

Power tool batteries: High-drain cells, usually in better condition. Dewalt, Milwaukee, Ryobi packs contain quality cells.

E-bike batteries: Largest cells, highest capacity. Often discarded when BMS (battery management system) fails, not when cells are dead.

Medical devices: Defibrillator batteries, portable oxygen concentrators. Premium cells, often lightly used.

Electric vehicle batteries: Tesla modules, Leaf packs. Extreme caution required—high voltage (400V+), massive energy, thermal runaway risk. Not for beginners.

Testing and Sorting Salvaged Cells

Step 1: Visual inspection

Discard any cells with: dents, rust, leaking electrolyte, swollen cases, burnt spots
Check voltage with multimeter. Below 2.5V = likely damaged. Above 4.2V = overcharged, possibly dangerous.
Target range: 3.0V-4.1V indicates healthy storage voltage.

Step 2: Capacity testing

Charge to 4.2V using lithium charger (TP4056 modules are cheap and effective)
Discharge through known load while measuring
Calculate capacity: (Current in amps) × (Time in hours) = Ah
Sort by capacity: Group similar-capacity cells together (within 100mAh)

Step 3: Internal resistance (optional but recommended)

Measure voltage drop under load
Lower resistance = better cell, less heat, higher current capability
Cells above 100mΩ internal resistance are tired but usable for low-drain applications

Building Battery Packs

18650 cell holder approach (safest for beginners):

Use plastic cell holders with nickel strip welding
No soldering directly to cells (heat damages them, risks fire)
Configure in series/parallel as needed
Add BMS (Battery Management System) mandatory for lithium

Soldering approach (dangerous but common):

Use high-wattage iron, work fast
Use nickel strips, not copper (lower thermal mass)
Pre-tin strips, quick touch to cell terminal
Have sand nearby for thermal runaway fires
Never solder to cell body (negative terminal is the can itself)

Configuration math:

Series (S): Adds voltage. 4S = 14.4V nominal (16.8V charged). Good for 12V systems.
Parallel (P): Adds capacity. 4P = 4× capacity, same voltage. Good for runtime.
4S10P = 40 cells, 14.4V nominal, 10× capacity of single cell.

Critical safety: The BMS

Prevents overcharge (stops at 4.2V per cell)
Prevents over-discharge (cuts off at 2.5-3.0V per cell)
Balances cells (keeps all at same voltage)
Prevents overcurrent (shuts down if shorted)
Never use lithium without a BMS. This is how houses burn down.

Solar Power: Harvesting Sunlight

Panel Types

Monocrystalline: Most efficient (20-22%), most expensive, longest lifespan (25+ years). Black cells, uniform look.

Polycrystalline: Less efficient (15-17%), cheaper, shorter lifespan. Blue cells, speckled look.

Thin-film (amorphous): Least efficient (10-12%), cheapest, flexible, works in low light. Good for portable applications.

Salvaged panels: Damaged panels, old off-grid systems, grid-tie upgrades. Often 50-80% of new cost, may have reduced output. Test open-circuit voltage (Voc) and short-circuit current (Isc) before buying.

Basic Solar Setup

The minimal system:

Solar panel (100W is a good starting point)
Charge controller (MPPT is more efficient, PWM is cheaper)
Battery (12V deep cycle or lithium)
Inverter (if you need AC) or DC loads directly
Fuses on every positive wire

Charge controllers:

PWM (Pulse Width Modulation): Cheaper, simpler. Matches panel voltage to battery by turning power on/off rapidly. Loses excess voltage as heat.
MPPT (Maximum Power Point Tracking): More expensive, 20-30% more efficient. Converts excess voltage to current. Worth it for systems over 200W.

Panel mounting:

Angle = latitude for year-round average
Angle = latitude - 15° for summer optimization
Angle = latitude + 15° for winter optimization
South-facing in Northern hemisphere (track sun arc)
Secure mounting critical—wind will destroy poorly secured panels

Off-Grid System Sizing (Rough Guide)

Step 1: Calculate daily usage

LED light bulb (10W) × 5 hours = 50Wh
Phone charging (5W) × 3 hours = 15Wh
Laptop (60W) × 4 hours = 240Wh
Refrigerator (100W average) × 24 hours = 2400Wh
Total: ~2700Wh/day

Step 2: Solar array size

Average sun hours per day (3-5 for most of US, winter less)
2700Wh ÷ 4 sun hours = 675W array needed
Add 30% for losses: ~900W array

Step 3: Battery size

Want 2-3 days autonomy (no sun)
2700Wh × 3 days = 8100Wh storage needed
12V system: 8100Wh ÷ 12V = 675Ah battery bank
Lithium: 675Ah × 0.8 (don't discharge below 20%) = 843Ah
Lead-acid: 675Ah × 0.5 (don't discharge below 50%) = 1350Ah

This is why off-grid is expensive. A 900W panel array and 1350Ah lead-acid bank is serious infrastructure.

DIY Battery Chemistries (Salvage and Build)

Lead-Acid (The Old Standard)

Salvage from: car batteries, UPS units, solar backup systems, mobility scooters.

Testing:

Load tester (cheap at auto parts stores)
Specific gravity with hydrometer (tells state of charge)
Voltage under load (12.6V+ is good, below 12V is tired)

Reviving "dead" lead-acid:

Often just stratified electrolyte (sulfuric acid heavier than water)
Carefully remove caps (wear safety gear)
Add distilled water if plates are exposed
Equalization charge (controlled overcharge) can break down sulfation
Epsom salt (magnesium sulfate) in electrolyte sometimes helps
Warning: Explosive hydrogen gas during charging. Ventilate. No sparks.

DIY lead-acid from scratch: Doable but dangerous. Lead plates, sulfuric acid electrolyte, plastic case. Sulfuric acid is available as drain cleaner (concentrated) but requires extreme caution.

Aluminum-Air Batteries (Emergency Power)

Simple chemistry: aluminum + oxygen + electrolyte = electricity + aluminum hydroxide.

Construction:

Aluminum foil or plate (anode)
Carbon cloth or graphite (cathode)
Salt water or lye solution (electrolyte)
Paper towel separator

Characteristics:

Low voltage per cell (~1.2V)
High energy density (aluminum stores lots of energy)
Not rechargeable (consumes aluminum)
Extremely cheap materials
Emergency power when nothing else works

Scale up: Multiple cells in series for higher voltage. Useful for LED lights, phone charging in emergencies.

Earth Batteries (The Original)

Two dissimilar metals buried in soil with moisture = battery.

Materials:

Copper pipe or wire (cathode)
Zinc-coated iron (galvanized nail, anode)
Wet soil or salt water (electrolyte)

Voltage: ~0.5-1.0V per cell depending on soil chemistry

Applications:

Very low power (LEDs, sensors)
Lasts years if metals don't corrode completely
Free energy from soil chemistry
Multiple cells in series for higher voltage

Historical note: Used in early telegraph systems. The original off-grid power.

Thermoelectric Generation (Peltier/Seebeck)

Principle: Temperature difference across special semiconductor junctions creates electricity.

Salvaging TEC modules:

CPU coolers (the hot side/cold side plates)
Mini fridges
Car drink coolers
Thermal imaging equipment

Power output:

Small modules (40mm): 1-5 watts with good temperature differential
Larger modules: 10+ watts
Requires hot side (stove, candle, solar) and cold side (heatsink, water, ice)

Applications:

Camping: Candle-powered phone charger
Stove-top: Wood stove fan (no batteries needed)
Body heat: Wrist-worn devices (very low power)

Limitations: Low efficiency (5-8%), requires constant temperature difference.

Human-Powered Generation

Hand-Crank Generators

Salvage from: emergency radios, military equipment, vintage field telephones.

Output: 5-20W sustained, bursts to 50W+.

Useful for: Emergency phone charging, radio operation, lighting.

Bicycle Generators

Bottle dynamo: Presses against tire, generates AC while riding. Vintage but effective.

Hub dynamo: Built into wheel hub, low drag, reliable. Expensive new, salvageable from old bikes.

DIY: Car alternator + bike stand + fan belt. Can generate 100W+ with effort.

Storage: Rectifier (AC to DC), capacitor or battery buffer, charge controller.

Energy Harvesting: Scavenging Micro-Power

Piezoelectric

Source: Crystal produces voltage when compressed (quartz, Rochelle salt, PZT ceramics).

Salvage: Buzzers, sensors, BBQ igniters, old phone receivers.

Application: Footstep power (floor tiles that generate when walked on), vibration harvesting from machinery.

RF Harvesting

Principle: Antenna captures radio waves, rectifier converts to DC.

Salvage: Crystal radio kits, AM radio circuits.

Output: Microwatts to milliwatts. Useful for sensors that transmit rarely, not for meaningful power.

Thermal Gradients

Peltier (mentioned above)

Thermocouples: Two dissimilar metals generate voltage from temperature difference. Very low power, used for temperature sensing and tiny trickle charging.

System Integration and Safety

Fusing and Protection

Every positive wire gets a fuse:

Panel to controller: Fuse rated for panel Isc × 1.25
Controller to battery: Fuse rated for controller max current
Battery to loads: Fuse rated for wire capacity
Inverter: Built-in or external breaker

Why: Short circuits become fires. Lithium fires are particularly bad—thermal runaway releases oxygen, making them self-sustaining.

Wire Sizing

DC systems lose voltage quickly:

12V system: Keep wire runs under 10 feet when possible
Use voltage drop calculators
Oversize wire (thicker = less resistance = less heat = less voltage drop)
10AWG minimum for 20A circuits, 6AWG for high current

Grounding

Essential for AC systems. Prevents shocks, lightning damage.

Ground rod 8 feet deep
Bond all metal enclosures
Neutral-ground bond only at main panel
DC systems (solar/battery) also benefit from grounding for lightning protection

Collapse Considerations

What Fails First

Grid-tied solar: Inverter shuts down when grid fails (anti-islanding protection). Useless during blackout unless you have battery backup and hybrid inverter.

Generators: Fuel runs out. Carburetors gum up. Maintenance intensive. Noisy—draws attention.

Lead-acid batteries: Sulfation if left discharged. Electrolyte evaporates. 3-5 year lifespan in practice.

Lithium: BMS failure kills pack. Thermal runaway if damaged. Requires working electronics ecosystem.

Long-Term Sustainability

Solar panels: 25+ year lifespan, gradually degrading (0.5%/year). Eventually wear out but last decades.

Charge controllers: Electronic failure after 10-15 years. Salvage spares, learn to repair.

Lead-acid: Can be rebuilt indefinitely with new plates and acid (if you have lead and sulfuric acid chemistry).

Human power: Bicycle generators work as long as bikes exist. No fuel, no sun required.

Thermoelectric: Solid state, no moving parts, last decades. Low output but reliable.

The Real Prep

Not: Buying a pre-built solar generator and storing it.

Instead:

Learn to test and sort lithium cells now, while e-waste is abundant
Build a small system and use it daily (knowledge is the asset)
Salvage components before they're rare
Document everything (voltages, configurations, troubleshooting)
Build community—one person with solar can't watch it 24/7

The Ethics of Salvage

Is taking batteries from recycling centers theft?

Recycling centers sell batteries to reclaimers. You're reclaiming them first. The real crime is letting lithium—mined by exploited workers, shipped across oceans, built into planned-obsolescence devices—end up in landfills because extraction was inconvenient.

Is it dangerous?

Yes. So is dependence on a fragile grid. So is not having light during a blackout. So is being unable to communicate when cell towers fail.

DIY energy is risky. But the alternative—dependence on systems designed to extract value rather than provide resilience—is riskier.

Charge your cells. Build your packs. Harvest your sun.

The power is already there, waiting in the waste stream, falling from the sky, sitting in the soil. The only question is whether you'll learn to take it back.