using part of the dc PORT

[MrDEB]

SLEEP that just might do it. Had a thought about SLEEP but never went any further.
If I have this right, power the transmitter off a PIC pin as well as the encoder maybe (I recall the encoder uses uma on standby).
Will try this out. Shouldn't make too much difference using a 18F2420 for testing but use a 18F25L20 in final design.
Hopefully not looking at an interrupt. This was discussed and it sounds complicated.

 

[JonSea]

With less than 30 seconds of searching, I was able to find data sheets on at least **broken link removed**. The results don't bode we'll for this project.

A Sanyo lithium CR2032 is rated for 0.4 mA continuous draw. The maximum recommended continuous current draw is 4 mA. For pulsed loads, the maximum rated current is 20 mA for 15 seconds. Your matrix is drawing more than that by itself. I'm assuming you want people to notice your blinkers so they will be on some amount of time more than a few seconds (although your recent code showed them active for 1 second and locked out for two).

The transmitter, if wired correctly, should only be drawing significant current while transmitting...at least according to the documentation, so if it's drawing 6 mA just waiting around, you should check that.


You might consider keeping all your posts on this project in the same thread. If somebody is trying to follow along, it's tough to see how all the pieces relate as they are spread around several forums and numerous topics.

 

[be80be]

The transmitter don't have leds Jon but your right I didn't even think about him using CR2032 cause he said 3.6 volts
those are 3 volt battery's but it's still the same there not going to last long. Maybe 4 hours if you don't turn it on.

It' hard to tell he has a led on it to tell if it's on 10mA Like I said coin battery operated transmitters only use power then keyed on or the battery's will not last long. It's not like you have to wait for the tubes to warm up LOL.

 

[MrDEB]

Thanks for the input Jon but the matrix is powered off of 6 C cell batteries. The transmitter is powered off the coin cell.
I will recheck the data sheets on the batteries. I am positive I saw somewhere it said 3.6v
The main reason I am using a coin cell battery is small compact and light weight. I started looking at other btteries and the wife called me for dinner. Got sidetracked.
THANKS again. Going to look into Burts suggestion of powering the transmitter off of a port pin and putting the PIC to sleep but don't think it will sleep much while in use.

 

[MrDEB]

contemplating going w/ 2 AAA batteries as three is heaver than I want.
Looking at the 1/3 AA batteries.
My constraints are light weight and footprint less than 50mm x 50mm (present board design is 45 x 46
rechargeable would be nice but kinda spendie with batteries and charger.

 

[Mosaic]

Lithium ion 10440 3.6V Cells, approx 11 grams.
https://www.batteryjunction.com/10440.html
]

 

[be80be]

MeDeb stay away from Lithium ion battery's please. I'm not saying this in a bad way but you don't want any one riding around with a fire ball. These bigger battery's can really make a fire.

WARNING: THIS BATTERY IS NOT MEANT TO BE A DIRECT REPLACEMENT FOR AAA ALKALINE/NIMH BATTERIES IN CONSUMER DEVICES. THESE LITHIUM ION BATTERIES OPERATE AT MORE THAN TWICE THE VOLTAGE OF AN ALKALINE BATTERY AND 3 TIMES THE VOLTAGE OF A NIMH CELL AND MAY DAMAGE OR DESTROY YOUR DEVICE.

There was a young man over at the arduino forum that found this out it smoked the reverse polarity circuit

 

[MrDEB]

I noticed the cordless phone batteries I just replaced next to my chair and investigated.
light weight, 400mah rating,right size, ni cad batteries.
Got to thinking, lets say I output a transmitting pulse every 5 seconds (pulse is 2seconds long 12 pulses per hour = (15ma x 12 = 180ma per hour. A 240mah battery won't last as pointed out.
Them AAA batteries are looking better all the time but want 4.5v so it can run longer before dropping below 2.4v.

 

[Mosaic]

I noticed the cordless phone batteries I just replaced next to my chair and investigated.
light weight, 400mah rating,right size, ni cad batteries.
Got to thinking, lets say I output a transmitting pulse every 5 seconds (pulse is 2seconds long 12 pulses per hour = (15ma x 12 = 180ma per hour. A 240mah battery won't last as pointed out.
Them AAA batteries are looking better all the time but want 4.5v so it can run longer before dropping below 2.4v.

MrDEB:

A pulse every 5 sec is 12 per minute = 720 per hour.

If u mean a pulse every 5 mins consumes 15mA for 2 seconds, then a 400mAh battery will last (400 x 3600)/ (15 x2) = 48000 pulses or 48000x5 = 240,000 mins or 166.6 days continuous use.
Estimate half of that for usable voltage battery capacity.

 

[MrDEB]

My math skills suck but I think I posted the explanation incorrectly.
A 2 second pulse every 5 second interval (60 seconds / 5 seconds = 12 pulses per minute)
Each pulse draws 15ma.
12 per minute = 720 per hour?
not saying I am correct but hopefully will either make it more confusing or clear?
Now my question is at 15ma per pulse, how long will the battery last. The 15ma is for 2 seconds per pulse so is it 15ma per second or 15ma per minute or ??
Now I am lost, too much celebrating last night.
what is the 3600

 

[MrDEB]

To make things easy and going in reverse so to speak, I found two small enclosures that might do the deed. One houses two AA batteries while the second houses two AAA batteries.
So taking enclosure size, weight, battery capacity (1250mah vers 2850mah) I need to rethink my board design to fit into enclosure. I realize a 9v battery might be better but??

 

[MrDEB]

Battery caculations gone bezerk!

Not saying anyone is right or wrong but using this calculator https://www.oregonembedded.com/batterycalc.htm
And a cr2032 battery , 15ma current draw and on continuously with 60 wake-ups per hour it comes up with 31 days!
this is of coarse going below the 2.4 I need.
This link is where I came up with 3.6v for the 2032 battery.
I want more voltage reserve so looks like the AAA is my choice?

 

[MrDEB]

Somewhere there has to be an artical on designing a battery device and show battery degrading.
I found a different sort of battery computation BATTERY CAPACITY / CONSUMPTION X .70
am assuming the .70 is 70% of battery capacity.

 

[MrDEB]

battery life caculator

pretty good reference to calculating how long a battery should run for.
I need to make some hardware as well as programming changes but am targeting 50ma for 72 hours for the 5 x 7 matrix and 15ma for 72 hours. Both are intermittent ON time.
Both apps using AA batteries (2700mah).
One issue I hope works out is the matrix running on 6v. While testing code I found that when a 9v battery dropped below 4.3v the LEDs went dim. NOTE the matrix is controlled using a constant current sink chip(tlc5916/5917) set at 26ma per led segment.
Not much headroom between 4.3 and 6v but after I make changes I might get the current draw less.


https://www.powerstream.com/battery-capacity-calculations.htm