Question on Battery power

Thread Starter

gwfami

Joined Jan 18, 2018
50
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?
 

MrChips

Joined Oct 2, 2009
30,925
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.
 

crutschow

Joined Mar 14, 2008
34,676
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?
 
Last edited:

Thread Starter

gwfami

Joined Jan 18, 2018
50
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.
 

crutschow

Joined Mar 14, 2008
34,676
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-
 

Thread Starter

gwfami

Joined Jan 18, 2018
50
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-
 

ian field

Joined Oct 27, 2012
6,536
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.
 
Top