Cordless tools, solar-charged tools and generator-run tools stay useful when the grid is down, but only in proportion to the energy you can supply, so use them for jobs that would take at least five times longer by hand and keep a hand-tool alternative for everything else. The battery is the limiting item: charge it from the sun or a vehicle alternator, never let a lithium-ion pack discharge fully, and never charge one that is swollen or damaged.
Part of Tool Identification & Repair
Power tools are transformatively useful while their batteries are charged and nearly useless when they are not, so the question is always where the next charge comes from and whether the job is worth it.
A Power Tool Is A Hand Tool Plus An Energy Bill
Every powered tool does a job faster than its hand equivalent and, in exchange, takes energy that has to be generated, stored or burned. Without a grid the energy comes from one of three places: a battery you charged from sun or a vehicle, a generator burning fuel you salvaged, or your own muscles. Each has a cost, and the cost tells you when a power tool earns its place.
The parent article puts the rule of thumb for battery tools at tasks that would take five times or more longer by hand: drilling, driving screws and cutting metal are worth it, sanding is not. For generators the bar is higher, ten times or more, because fuel is finite and generators are loud.
What You Need
- Cordless tools and their batteries and chargers, kept together as sets.
- A charging source: a solar panel with a charge controller, a vehicle with a working alternator and an inverter, or a generator.
- Hand-tool equivalents for each power tool, see Manual Alternatives to Power Tools.
- Eye and ear protection.
Method: Decide Before You Plug In
Step 1: List the jobs. Write down what needs doing and estimate how long each would take by hand and by power.
Step 2: Apply the thresholds. Jobs below the thresholds go to hand tools. Jobs well above them go to power tools.
Step 3: Choose the energy source. Small batteries come from solar or vehicle charging; see Cordless Tool Battery Management. Heavy or long jobs, such as cutting steel or drilling concrete, may justify a generator; see Generator & Solar Options.
Step 4: Batch the work. Run the generator or charge the batteries once, and do all the powered tasks in one session.
Step 5: Keep the backup. Never retire a hand tool because a power tool does the same job.
Common Mistakes
- Using power tools for every job. The battery is gone when you need it for a job only the power tool can do.
- Running a generator just to charge one battery. It burns fuel for a small load.
- Throwing away corded tools. They run from a generator or inverter and are often sturdier than cordless ones.
- Forgetting the charger. A battery without a compatible charger is dead weight.
Safety
Lithium batteries burn, and generators poison
A damaged, swollen or deeply discharged lithium-ion pack can overheat and catch fire; do not charge one that is swollen, hot or cracked, and keep packs away from flammables. Run generators and engines only outdoors, because their exhaust contains carbon monoxide (see CO Risk). Keep fuel away from the generator while it runs or is hot. Powered saws, grinders and drills throw chips and have no friendly failure mode: wear eye and hearing protection, and unplug or remove the battery before changing a blade or bit.
What’s Next
- Learn next: Cordless Tool Battery Management — keeping the packs alive
- Combine with: Manual Alternatives to Power Tools — the backup for every powered job