A time-tested method is to build a circuit breaker using a CSA and a power transistor. The CSA intensifies the small voltage drop across a sense resistor that is added in series with the battery.

If the supply’s voltage suffers a voltage drop, the voltage across R2 will drop also, reducing the voltage to the base of transistor Q1. That turns on Q1, which also starts IC1, an LMC555/TLC555 ...

Typically the current in the string is regulated by adding a sense resistor in series with the LEDs and using the voltage across it as the feedback to a PWM controller. If a fault occurs with any of ...

The MT3608 is a popular boost converter, able to easily step up DC voltages in useful ranges, at an incredibly low cost. Modules can be sourced from eBay for less than $2, built on a PCB, ready to … ...