Battery Drain after circuit wired
Battery Drain after circuit wired
(OP)
Hello all,
Couple quick questions...this is an aside from the LED Bargraph question I asked earlier...I took everyone's advice and got the LM3914 and it worked like a charm...much better than the complex circuit I was trying to devise. My only problem now is that it seems to be draining my battery quite a bit...I am using an 12V N-type battery since it is small however it seems to be draining in my circuit quite fast (After 3 days of very sparse use it is already down to 8 V). It is not affecting the circuit yet as I got the LM3914 and the Bargraph to run well off of 3Volts, but just wondering if anyone has had similar experience with those type of batteries or could recommend a small battery with a high voltage. I plan to put this inside a rather small space.
I also hooked up two LEDs off the side of the same circuit operated by a switch...obviously when the Bargraph is fully lit there is not enough juice to power the LEDs, but just wondering if this may be causing any issues...should I have also put some resistors in there or should they be ok?
Any thoughts would be great. Thanks!!
Couple quick questions...this is an aside from the LED Bargraph question I asked earlier...I took everyone's advice and got the LM3914 and it worked like a charm...much better than the complex circuit I was trying to devise. My only problem now is that it seems to be draining my battery quite a bit...I am using an 12V N-type battery since it is small however it seems to be draining in my circuit quite fast (After 3 days of very sparse use it is already down to 8 V). It is not affecting the circuit yet as I got the LM3914 and the Bargraph to run well off of 3Volts, but just wondering if anyone has had similar experience with those type of batteries or could recommend a small battery with a high voltage. I plan to put this inside a rather small space.
I also hooked up two LEDs off the side of the same circuit operated by a switch...obviously when the Bargraph is fully lit there is not enough juice to power the LEDs, but just wondering if this may be causing any issues...should I have also put some resistors in there or should they be ok?
Any thoughts would be great. Thanks!!





RE: Battery Drain after circuit wired
RE: Battery Drain after circuit wired
One trick is to use super bright LEDs, but run at very low current (less than 1mA, instead of 10mA or more). If you're using a BarGraph Display assembly, you may not have this option.
IIRC, that family of ICs offer the choice of having a bar graph (many LEDs illuminated), or having a single LED at a time illuminated (just one at a time). You might need to wire up the bottom LED as a visual reference point if just using one LED at a time (if you're using it in the dark and can't see the printed display).
Also, maybe change the power switch to a press and hold button. The user will tend to leave the device off unless he is actually looking at the display.
RE: Battery Drain after circuit wired
I also have two regular LEDs...I have tried varying resistances in there...when I put a 150K resistance in there everything seemed to work fine but I got a large measurement for the current (around 30-40 mA).
Any advice would be great...I have a schematic that I drew in PSPICE but it is non operational (just pictoral) if anyone has time to take a look and let me know what changes they think I should make. Let me know. Thanks!
RE: Battery Drain after circuit wired
When you say that the "two regular LEDS with 150K resistor measure about 30-40mA" are you talking about the overall current drain or just the two LEDS? If it's that second choice then you must be measuring it wrongly since the maximum current you could draw from 12v with a 150K series resistor is 80 uA.
RE: Battery Drain after circuit wired
RE: Battery Drain after circuit wired
The big problem is that per Duracell datasheet: http://www.duracell.com/oem/Pdf/MN21.pdf
the MN-21 battery only has a capacity of about 40 mAHr on a good day
TTFN
RE: Battery Drain after circuit wired
RE: Battery Drain after circuit wired
the part is equivalent to the MN-21
TTFN
RE: Battery Drain after circuit wired
RE: Battery Drain after circuit wired
TTFN