excessive battery consumption
I have a problem with a BS2 and some other circuitry with its power consumption, to be exact I’m using a EDE-1144 keypad encoder and some other stuff to open a door, the circuit works perfectly for about a day then my 4 brand new AAA batteries are dead in less then 24 hours. With a 6v supply its pulls about 7mA, how bad is this, what should the current be for the batteries to last a few months.
The code i'm using is based off an example Chris Savage posted a few months ago...if this means any thing
The code i'm using is based off an example Chris Savage posted a few months ago...if this means any thing
Comments
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Jason
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He who dies with the most toys wins!
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Chris Savage
Parallax Tech Support
csavage@parallax.com
But he's seeing the pack drained in less than 24 hours. So there's a lot of current leaving the battery that he's not measuring somehow. Or, the battery pack isn't 1100 mA-Hours.
ps. no display, just a LED, a beeper and a 3v relay, its a pretty simple circuit
Post Edited (turboEK2000) : 8/3/2006 2:11:41 AM GMT
You still won't get past the issue that resitive regulators waste power as heat dirrectly related to the voltage they are scrubbing while they are regulating. For better results long term, use a switching regulator. Sounds exotic, but they are pretty simple to make (and cheap).
Go here: www.romanblack.com/smps.htm
Two transistors will do it.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
now I just measured the output of the regulator with the half dead batteries and its at 4.4V, so this would cause the Stamp and EDE1144 not to work????
I'm going to·throw another cell in there as Larry suggested...
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Chris Savage
Parallax Tech Support
csavage@parallax.com
If you were to take the leap to the·SX, it has a 'SLEEP' function which can be interrupted by a keypress interrupt.· The SX's current draw in it's 'SLEEP' mode is 1uA or less.· You can also easily integrate the keypad scanning into the SX programming·to cut down on current draw and parts count at the same time.· (With the SX, a LED, a beeper and a 3V relay, you wouldn't even need the voltage regulator (run off batt. direct) - talk about simple!)
Nate
The LM2940 that is used on the BOE is low dropout but _not_ low quiescent current.
The LM2936 that is on the BS2 module and the LT1121 that is on the multibank BS2s are both low dropout (0.2 volt) and low quiescent current (<100 microamps). The LM2936 can supply up to 50 milliamps, which must include the 3 ma for the Stamp itself but can also include 40ma of external loads. If your whole system draws only 7 ma, you might dispense with the external regulator and just use the Stamp's Vdd.
You asked, "what should be the current to last for a few months?" The battery capacity of AAA alkalines is 1200 ma-h. In 4 months there are about 1464 hours. Divide:
1200 / 1464 = 0.82 milliamp.
data.energizer.com/ <-- great info and tutorials
I'm not familiar with the EDE-1144, but to reach that lower current consumption your system will have to do some napping or tricks.
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Tracy Allen
www.emesystems.com