Question of selecting the right battery for 3V, 350mA Laser module.

Other Hardware General Electronics
1

Hi,

I had unexpected experience yesterday from the testing device I made.
I bought a green Laser module to build a cross line level.
Power output: 50mW
Wavelength: 532nm
Threshold current: 250mA
Maximum current: 350mA
Requirements Voltage: 3V
Working Temperature: +20???30?
Storage Temperature: -10???60?
Life span: >5000hours
Size: Line/Cross: 12mm x(40+19)mm

It had two AAA batteries, one switch.

I didn't measure the running time till the laser module went dark accurately but
it the first two batteries gave up within 15 minutes.
The initial voltage was 3.2 V and it dropped to 2.7V which wasn't
enough voltage for the laser module. So I had to replace them with two new batteries.

Assuming AAA battery's capacity is 1000mAH, a set of two AAA batteries should run the laser module
2.8 hours at 350mA in theory. But I doubt it wouldn't run over 1 hour.

http://www.batterysavers.com/Compare-Batteries.html

AAA 1 Amp or 1000 mAh / runs for 1 hours
Capacity 1000 mAH
Designed for Typical drain 10 mA

My question is what's good battery capacity for this Laser module?

Most battery powered line lasers runs 10 to 12 hours per a set of AA batteries.
To match those run time, I think I use a bigger battery or user a low power laser module.
Connecting 10 AAA batteries in parallel increase the drain to 100 mA, which is stupid setting IMHO.

Secondly are there power supply circuits for the high efficiency device that
I can implement relatively low cost under $20?

Thanks in advance,
Hughe

2

I don't see a real heatsink on your laser - what was the specification for its duty cycle? Usually well under 50% averaged over a couple of minutes for a laser (pointer module) rated at 1W input.

You were of course using alkaline batteries, were you not? Not "plain" Zinc-Carbon.

Triple-A? 350 mA? Sounds optimistic - remember these have no more than a third of the capacity of corresponding AA (if that).

3

There are so many power supplies for your setup, just search your local hardware shop.

And you are "Assuming" that your cells are 1000mAH right? Where they rechargeable cells or one-time-use?
Rechargeable cells have the tendency to measure 1.7V when charged but after a small load is applied they drop to about 1.3V.

If a cell is designed for a typical drain of 10mA don't try to connect it, they'll break and start leaking.

4

18650 rechargeable 3000mAh Lithium-ion battery seems good candidate for the device.

5

Indeed it does!

6

As you've discovered, batteries marked 1.5V hardly ever give 1.5V (they give a variable value down to about 1V depending on load and lifetime)).

You need more batteries (higher voltage) and something like this: Pololu Step-Down Voltage Regulator D24V6ALV

The more batteries, the longer it will last (higher input voltage means less input current).

7

janpenguin:
Connecting 10 AAA batteries in parallel increase the drain to 100 mA, which is stupid setting IMHO.

Connecting batteries in parallel is a very bad idea. Don't do it.