So I'm working on using a joule thief to power an LED for an expanded period of time in a confined container. I've done testing using a 1.5V LR44 button battery, but I'm wondering if I could get a longer life using an 12V 23A battery. I know the voltage is quite a bit different, but I'm not sure how much power would be wasted in reducing the voltage via resistors to 1.5V so the LED doesn't explode. Any ideas?

 

You can use a 10kΩ resistor in series with the LED. A 12V 20Ah battery should last for a few years.
Pulse the LED at a low duty-cycle and the battery will last for a very long time.

 

You could use a 1.5V battery with a larger capacity, such as an AAA.

Why do you want to go to a 12V battery?

 

Size is extremely important. AAA is too large for the container.

 

You can use a 10kΩ resistor in series with the LED. A 12V 20Ah battery should last for a few years.
Pulse the LED at a low duty-cycle and the battery will last for a very long time.

Thanks.

 

Size is extremely important. AAA is too large for the container.

Then how will a 12V battery fit?
If it's that small, it won't last as long as the 1.5V battery.

 

An A23 battery is cylindrical ... measuring 28.5 mm long and 10.3 mm in diameter, with a typical weight of 8 grams. An A23 battery is an 8-cell device with a nominal voltage of 12 V. The higher voltage is necessary for the radio frequency-transmitting and receiving devices which A23 batteries often power. It has a capacity of around 55 mAh. - Wikipedia.

A triple-A battery is a single cell and measures 10.5 mm (0.41 in) in diameter and 44.5 mm (1.75 in) in length, including the positive terminal button, which is a minimum 0.8 mm (0.031 in). The positive terminal has a maximum diameter of 3.8 mm (0.15 in); the flat negative terminal has a minimum diameter of 4.3 mm (0.17 in).[1] Alkaline AAA batteries weigh around 11.5 grams (0.41 oz), while primary lithium AAA batteries weigh about 7.6 g (0.27 oz). Rechargeable nickel–metal hydride (NiMH) AAA batteries typically weigh 14–15 g (0.49–0.53 oz).
- Wikipedia.

Although AAA batteries range from 350 to 1250 mAh compared to the A23 at 55 mAh, the AAA battery is nearly twice as long, making it too long for the case.

 

Why not use a CR2032 button cell?

 

It's diameter is too big, need to keep it under 1/2 inch.

 

How about an N cell?

The battery has a length of 30.2 mm and a diameter of 12.0 mm, with a capacity of 800-1000mAh for the alkaline version.
-Wikipedia-

 

Hadn't thought about that. I'll have to check and see as the diameter is just under 1/2 inch. Thanks.

How about an N cell?

The battery has a length of 30.2 mm and a diameter of 12.0 mm, with a capacity of 800-1000mAh for the alkaline version.
-Wikipedia-

 

So I'm working on using a joule thief to power an LED for an expanded period of time in a confined container. I've done testing using a 1.5V LR44 button battery, but I'm wondering if I could get a longer life using an 12V 23A battery. I know the voltage is quite a bit different, but I'm not sure how much power would be wasted in reducing the voltage via resistors to 1.5V so the LED doesn't explode. Any ideas?

The resistor would waste more energy than the LED uses and the 12V battery is a stack of button cells - more of the total volume is taken by metal cell casing.

 

I also think a switching voltage regulator would be better as the resistor would use 5ma x 10v = 50mW/h. The LED will use 5ma x 2v = 10mW/h.

 

I also think a switching voltage regulator would be better as the resistor would use 5ma x 10v = 50mW/h. The LED will use 5ma x 2v = 10mW/h.

You have to know what you're doing to current limit a switcher.

 

You have to know what you're doing to current limit a switcher.

What do you mean exactly?

 

If its put a resistor to make the circuit a current regulator and not a voltage regulator, I know that?

 

What do you mean exactly?

A switcher is fundamentally an average voltage controller - filtering is probably the easiest way to make it behave like a constant current generator.