For first responders or roadside assistance, you can install specialized strobe and warning systems. Installation Steps

: Strap an LED headlamp or flashlight to a full plastic milk jug. The water refracts the beam, creating a glow similar to a 55-watt bulb.

: Always install an inline fuse within six inches of the battery to protect the circuit from shorts.

If you want to build a basic battery-powered lamp that turns on when the power goes out, you can assemble a simple circuit. Essential Components : High-brightness 1W or 3W LEDs. Power Source : A 3.7V Li-ion cell (like an ) or a 12V lead-acid battery. Charging Module : A TP4056 controller Go to product viewer dialog for this item.

for Li-ion batteries to keep them charged while the main power is on.