Add a low power indicator LED

Status
Not open for further replies.
J

jack0987

Member
I have some small battery powered Arduino sensors in plastic cases about the house.

My thinking is I would like to drill a small hole and put an led behind it to add a small indicator led to each so when I look up at them and the led is lit I know the battery is not dead yet.

The Arduino runs on low power and only wakes up on an interrupt. With a T5 led ran for about 10 days. The Arduino has an led and so far it has run 90 days.

Perhaps size matters.

Please suggest some ideas. low cost is best.

Edit: Changed thread Title
 
Last edited:
Sort by date Sort by votes
When you measure Arduino current lift the power pin on the Arduino as the
board uses current for the RS232 interface and other stuff. If you want its real
current measur.re it there.

Depends on the board/proto setup you are working on.. Note you want
the LED driven by the Arduino so its power is supplied thru Arduino supply pin.

Or make sure where you decide to measure current the LED is supplied with
power.

Note a DSO also makes it easy to measure total power consumed over time
with its math functions.


Regards, Dana
 
Last edited:
Upvote 0 Downvote
jack0987 said:
Blink rate and duration may also be taken into consideration.
Click to expand...
As I suggested testing in post #20 - I suspect you will be surprised how short a flash you can get away with. Depending exactly what your application is you may be able to add extra functionality by flashing at different speeds or intervals, I use this on a device we manufacture to give an indiction of battery life - slow flashing when fully charged, getting faster as it discharges.

I monitored the battery charging and discharging voltages and currents, and send them out the serial port to a PC and wrote them to a comma delimited file. Then I used EXCEL to generate graphs based on the charge and discharge characteristics (you only need voltage for discharge), then simply grabbed values at 100%, 90% etc. down to 10%. Once it gets to the 0% point everything is turned off.
 
Upvote 0 Downvote
Our discussion has been interesting, but I do not feel that I am any farther ahead than when I started.

I remain uncertain that continuously powering up the processor for a blink will save battery power instead of running a very low power LED all the time.

My Arduino processor has a built in power LED. So far, my test with it on all the time has run now for nearly 120 days. I felt that making up an indicator with a tiny one like that might be the way to go for now and I'll look into processor blinking later.

So, I took one of the Arduino LEDs off a non-working board but I am finding very hard (near impossible) to work with because it is so small.

Am I right in assuming that the Arduino's LED consumes less power?
I do not know what to look for in the hundreds of types available.

Can you suggest a blue one of similar specs that I can work with?
 
Upvote 0 Downvote
How can you be 'uncertain'?- an LED on all the time uses ten times the power of one that's only on 10% of the time - so will only last 1/10th of the time. You don't 'continuously power up the processor', it's in sleep almost all the time, which presumably it already is anyway?.

What don't you understand about that?.
 
Upvote 0 Downvote
jack0987 said:
Thanks. For low power, should I choose one with the lowest forward voltage?
Click to expand...
Nope! You want the one with the lowest current that will produce an acceptable level of illumination. Since the LED will have a persistence when the current is removed you want to find a duty cycle that will give the visible illumination required with the minimum possible current.
 
Upvote 0 Downvote
Thanks. I know, I know, I am hard at times. LOL

Anyway, for the time being, I Found this:


Specs say 2mA.

3mm ones I was going to use say 20 mA.

I think I'm getting the hang of it and have been looking in the wrong places.
The sensors are about the house and I can easily modify them later.
 
Upvote 0 Downvote
Considerations for sleep mode :

Understanding MCU sleep modes and energy savings - Embedded.com

Whether they’re used in smart meters, wireless sensor nodes, or mobile health monitoring products, microcontrollers (MCUs) are at the heart of almost
www.embedded.com

Here is a representative processor and results :



Regards, Dana.
 
Upvote 0 Downvote
Far more important than the test current spec, is the luminosity at that current.
The part you link to will put out ~64 mcd at 2 mA.

Here is a part that puts out ~1600 mcd at that same 2 mA.
https://www.digikey.com/en/products/detail/kingbright/WP7113LVBC-D/5177420

You can either run it at 2 mA, or reduce the current (and power) significantly, and still get a usable level of light.
 
Upvote 0 Downvote
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

K
  • Question
Low loss power OR-ing with MOSFETs & Op Amps
Replies
6
Views
2K
Karklebapper
K
S
  • Question
Low power consumption relays
2
Replies
23
Views
5K
Tony Stewart
D
LED driver
Replies
9
Views
1K
Diver300
D
J
Power Resistor
Replies
4
Views
218
Nigel Goodwin
led light bulb component
Replies
4
Views
880
aliarifat794
A
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…