Hi, I have a bunch of diverse LED lamps using 3 x 1.5v = 4.5v, some are remote controlled (IR) and work pretty well, no noticeable heat after prolonged use.
A single 18650 battery is rated around 3.7v but reaches 4.2v fully charge (depending on your charger it can be 4.2v or more), the difference in volts doesn't really matter: the problem is these can deliver more and faster amps than any set of 3xAA or 3xAAA batteries due differences on their internal resistance. It's really rare to find cheap lamps with an specialized circuitry, instead they rely on a resistance and the speed AAA batteries work. You could easily argue about details and specifics around this but in general this is the big picture, long story short just using 18650 causes the LEDs to overheat, or whatever sort of cheap regulator is used inside the circuit. Besides it is far from efficient.
I have used different current limit resistors, but it's not efficient and energy is wasted. Also tried the old LM317 as current regulator but only works on certain cases, as it's operation will also steal some volts reducing the power output. The old 555 needs some adjustments and anyway none of this would feature any undervolt/discharge protection.
I'm looking for a better and cheap way to do this. Any recommendation? perhaps there is an already integrated IC to do this. I'm a fan of electronics but due to little practice I'm a little rusty at present time.
- Is there an easy and practical way to convert these into 18650 battery operated?
- Is there a simple module or circuit that you would advice to use?
A single 18650 battery is rated around 3.7v but reaches 4.2v fully charge (depending on your charger it can be 4.2v or more), the difference in volts doesn't really matter: the problem is these can deliver more and faster amps than any set of 3xAA or 3xAAA batteries due differences on their internal resistance. It's really rare to find cheap lamps with an specialized circuitry, instead they rely on a resistance and the speed AAA batteries work. You could easily argue about details and specifics around this but in general this is the big picture, long story short just using 18650 causes the LEDs to overheat, or whatever sort of cheap regulator is used inside the circuit. Besides it is far from efficient.
I have used different current limit resistors, but it's not efficient and energy is wasted. Also tried the old LM317 as current regulator but only works on certain cases, as it's operation will also steal some volts reducing the power output. The old 555 needs some adjustments and anyway none of this would feature any undervolt/discharge protection.
I'm looking for a better and cheap way to do this. Any recommendation? perhaps there is an already integrated IC to do this. I'm a fan of electronics but due to little practice I'm a little rusty at present time.