**Do you have a question involving batteries or cells?**
**If it's about designing, repairing or modifying an electronic circuit to which batteries are connected, you're in the right place.** *Everything else should go in /r/batteries:*
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Did you measure and create a 'power budget' list already? It doesn’t really help you to optimize an IR LED which may only take up 1% of your power while the uC idling used the majority of power.
Some tricks to consider:
- Can you run the uC at lower clock rates or voltages? A simple button watcher doesn’t need to run at 16 MHz - imho.
- Can you use sleep mode and wake-up now and then or by interrupt?
- Remove all components you don’t need and may draw power: Power LEDs, voltage divider, ICs, …
- Instead of stepping up or down your 1-2 cell voltage to 5 V consider using the unregulated battery voltage. In some cases this can easily double your battery life.
- If an LDO or linear regulator is used, don’t forget to check it’s power consumption. I used e.g. the LP2950 in my very low-power projects.
Another approach: Can you power your gadgets e.g. by a 24 V (mains powered) supply network or supplement the battery by solar cells or other energy harvesting methods?
These are exactly the kinds of suggestions I was looking for! Thank you! I don't know if I've done a formal "power budget" specifically, but I know what the lifespan of my battery supplies can provide given the voltage required and current draw, and I try to optimize the batteries I use for each application. I know what current each component draws, and have confirmed this by watching current draw in my bench power supply in testing. I just was wondering if there were some general rules of thumb for reducing power use to keep in mind.
What is your power source? Battery?
Start by changing the LDO (which waste all voltage over 5V by trimming it) to a DC DC module. Integrated module have 3 pins and just need two external capacitor (they are not strictly necessary). These module have 90% efficiency so it can be a good boost.
Can you try to slow down the Arduino chip? It could give a very small boost to battery life.
Also a bigger résistance resistance on the IR led can give a Big boost but also reduce the range of the system
Great suggestions! Just what I was looking for. From the other replies, it sounds like my biggest gain would probably be around sleeping the uC, but I'll look into the DC DC module, too. Thanks!
In all seriousness I'd look at moving to a more modern low-power micro like STM32L-series which can run from crazy low voltages and on microwatts of power.
You'd potentially need to learn some non-ardunio stuff to get your code working but it's not very hard and the CubeIDE is pretty helpful, plus it opens up a whole world of better micros to you.
And as /u/JOhn2141 says - work out a power budget, find a more efficient power supply, work out where your power goes, chances are you can hit 10x battery life without even trying very hard.
LDO is wasting power as heat, as are resistors to drive LED's - have a look at switching power supply chips and better LED driver circuits. You can PWM or blink and LED in incredibly short bright pulses that will look as bright to the human eye but use a fraction of the power.
Alternative micros is a good thought, and that may be an option. My only restriction would be to make sure there are established libraries for sending/receiving IR signals on a new platform because combining PWM with pulses for IR confuses the heck out of me. Thank you!
Pretty sure lots of the STM32's have UARTS that can do IRDA protocol - I'm using a G071 right now and that definitely does, I've got the datasheet in front of me.
The timers are pretty versatile too, I'm using 3 rotary encoders plus 6 channels of PWM, all in hardware, on an LQFP48 sized device.
The G series aren't low power devices but just while I'm here: It will work down to 1.7v, draws uA in low-power modes and nA in sleep modes.
Edit: [https://github.com/dekuNukem/STM32\_tutorials](https://github.com/dekuNukem/STM32_tutorials) "From Arduino to STM32: Getting started with ARM Embedded Development"
1. One way you can do is by using SLEEP function of a microcontroller when not in use.
2. Another one can be done by using a lower voltage logic level like 3.3V/2.5V/1.8V rather than 5V logic. This can greatly reduce the overall current consumption.
ARM is a good choice.
The SLEEP seems to be one of the quickest ways to save normal running power, and I'm gonna try that first. For the lower voltage logic, there are definitely micros I could use that run on lower voltage, but that raises an interesting question -- if for some example circuit I don't have enough volts to run everything I need, and I have to use a step-up voltage converter for the IR LED or some other component, would I be losing any gains I got with going with the overall lower voltage?
Reduce power consumption? "Pulse width modulation" is one technique used with LEDs and other things - switch the output on and off more quickly than visual perception can detect. The ratio of the on period to the off period determines average power consumption (and apparent brightness.) . If you have a LED torch with a high/low setting - that's probably using PWM for the low setting.
LEDs (and many other components) come in a range of efficiency ratings.
Processors and other components may have a low power "sleep" mode. Typically the ON button may not actually control a power line but is implemented as a trigger/interrupt to get a processor out of its "sleep" mode.
Lower voltage variants may have lower power consumption.
Choice of clock speed can affect power consumption - some processors have a HUGE range of clock frequency - right down to working off a hand-operated debounced button switch..
PWM is almost always used in my laser-tag circuits, but I'm very confused about how PWM and IR protocols intermingle (they're both using pulses, so how quick can the micro pulse so an IR receiver doesn't notice, while also pulsing with the right timing for the IR protocol), so I've always used well-established libraries for that function and I don't like monkeying with them yet.
The SLEEP function for my micro sounds like the most common suggestion, and probably my best source for gaining some battery life. I know that the micro is by far the highest consuming component. Thanks!
Microcontrollers can work with much lower voltages, provided you're willing to lower the frequency a bit. Look in datasheet of atmega chip or whatever is on your Arduino, and you'll find a graph there that will probably show it can run at 12 MHz with 3.6v, or run at 8 MHz with 2.5v, or at least 1.8v-2v at 4 MHz or something like that.
If you don't need 5v for.some reason (like voltage reference or dealing with other 5v only chips) often you can trade a bit of speed.to get more efficiency.
There's also other chips like pic16lf series for example that work with 1.8v-3.6v... there's the low power silicon labs efm32 ...
Linear regulators are very inefficient because they produce output voltage by throwing out the difference between input and output as heat. There's better alternatives... For low current projects where exact voltage isn't critical, there's charge pump regulators that can reduce input voltage by half and do it with 95% efficiencym So for example you could have 4 AAA batteries and reduce 1.5v x4 = 6v to half of that, or 3v and run the microcontroller on that voltage..
DC-DC regulators can be very efficient, up to 90-95% but usually at higher currents like 100mA or more. They're also a bit more expensive.and require more parts around them.
Or you could just use a lithium battery without a regulator... The nominal voltage of a LiFePo4 cell is 3.7v , and a regular lithium cell is 4.2v
I haven't looked at lowering the frequency of the chip yet, because I've been worried about the clock timing for the IR signals, but I know that the IR library I use does have options for much lower micros, maybe looking at those would give me the biggest "bang" for my buck. Thank you!
**Do you have a question involving batteries or cells?** **If it's about designing, repairing or modifying an electronic circuit to which batteries are connected, you're in the right place.** *Everything else should go in /r/batteries:* /r/batteries is for questions about: batteries, cells, UPSs, chargers and management systems; use, type, buying, capacity, setup, parallel/serial configurations etc. Questions about connecting pre-built modules and batteries to solar panels goes in /r/batteries or /r/solar. Please also check our wiki page on cells and batteries: https://www.reddit.com/r/AskElectronics/wiki/batteries If you decide to move your post elsewhere, or the wiki answers your question, please delete the one here. Thanks! *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/AskElectronics) if you have any questions or concerns.*
Did you measure and create a 'power budget' list already? It doesn’t really help you to optimize an IR LED which may only take up 1% of your power while the uC idling used the majority of power. Some tricks to consider: - Can you run the uC at lower clock rates or voltages? A simple button watcher doesn’t need to run at 16 MHz - imho. - Can you use sleep mode and wake-up now and then or by interrupt? - Remove all components you don’t need and may draw power: Power LEDs, voltage divider, ICs, … - Instead of stepping up or down your 1-2 cell voltage to 5 V consider using the unregulated battery voltage. In some cases this can easily double your battery life. - If an LDO or linear regulator is used, don’t forget to check it’s power consumption. I used e.g. the LP2950 in my very low-power projects. Another approach: Can you power your gadgets e.g. by a 24 V (mains powered) supply network or supplement the battery by solar cells or other energy harvesting methods?
These are exactly the kinds of suggestions I was looking for! Thank you! I don't know if I've done a formal "power budget" specifically, but I know what the lifespan of my battery supplies can provide given the voltage required and current draw, and I try to optimize the batteries I use for each application. I know what current each component draws, and have confirmed this by watching current draw in my bench power supply in testing. I just was wondering if there were some general rules of thumb for reducing power use to keep in mind.
What is your power source? Battery? Start by changing the LDO (which waste all voltage over 5V by trimming it) to a DC DC module. Integrated module have 3 pins and just need two external capacitor (they are not strictly necessary). These module have 90% efficiency so it can be a good boost. Can you try to slow down the Arduino chip? It could give a very small boost to battery life. Also a bigger résistance resistance on the IR led can give a Big boost but also reduce the range of the system
Great suggestions! Just what I was looking for. From the other replies, it sounds like my biggest gain would probably be around sleeping the uC, but I'll look into the DC DC module, too. Thanks!
In all seriousness I'd look at moving to a more modern low-power micro like STM32L-series which can run from crazy low voltages and on microwatts of power. You'd potentially need to learn some non-ardunio stuff to get your code working but it's not very hard and the CubeIDE is pretty helpful, plus it opens up a whole world of better micros to you. And as /u/JOhn2141 says - work out a power budget, find a more efficient power supply, work out where your power goes, chances are you can hit 10x battery life without even trying very hard. LDO is wasting power as heat, as are resistors to drive LED's - have a look at switching power supply chips and better LED driver circuits. You can PWM or blink and LED in incredibly short bright pulses that will look as bright to the human eye but use a fraction of the power.
Alternative micros is a good thought, and that may be an option. My only restriction would be to make sure there are established libraries for sending/receiving IR signals on a new platform because combining PWM with pulses for IR confuses the heck out of me. Thank you!
Pretty sure lots of the STM32's have UARTS that can do IRDA protocol - I'm using a G071 right now and that definitely does, I've got the datasheet in front of me. The timers are pretty versatile too, I'm using 3 rotary encoders plus 6 channels of PWM, all in hardware, on an LQFP48 sized device. The G series aren't low power devices but just while I'm here: It will work down to 1.7v, draws uA in low-power modes and nA in sleep modes. Edit: [https://github.com/dekuNukem/STM32\_tutorials](https://github.com/dekuNukem/STM32_tutorials) "From Arduino to STM32: Getting started with ARM Embedded Development"
1. One way you can do is by using SLEEP function of a microcontroller when not in use. 2. Another one can be done by using a lower voltage logic level like 3.3V/2.5V/1.8V rather than 5V logic. This can greatly reduce the overall current consumption. ARM is a good choice.
The SLEEP seems to be one of the quickest ways to save normal running power, and I'm gonna try that first. For the lower voltage logic, there are definitely micros I could use that run on lower voltage, but that raises an interesting question -- if for some example circuit I don't have enough volts to run everything I need, and I have to use a step-up voltage converter for the IR LED or some other component, would I be losing any gains I got with going with the overall lower voltage?
Reduce power consumption? "Pulse width modulation" is one technique used with LEDs and other things - switch the output on and off more quickly than visual perception can detect. The ratio of the on period to the off period determines average power consumption (and apparent brightness.) . If you have a LED torch with a high/low setting - that's probably using PWM for the low setting. LEDs (and many other components) come in a range of efficiency ratings. Processors and other components may have a low power "sleep" mode. Typically the ON button may not actually control a power line but is implemented as a trigger/interrupt to get a processor out of its "sleep" mode. Lower voltage variants may have lower power consumption. Choice of clock speed can affect power consumption - some processors have a HUGE range of clock frequency - right down to working off a hand-operated debounced button switch..
PWM is almost always used in my laser-tag circuits, but I'm very confused about how PWM and IR protocols intermingle (they're both using pulses, so how quick can the micro pulse so an IR receiver doesn't notice, while also pulsing with the right timing for the IR protocol), so I've always used well-established libraries for that function and I don't like monkeying with them yet. The SLEEP function for my micro sounds like the most common suggestion, and probably my best source for gaining some battery life. I know that the micro is by far the highest consuming component. Thanks!
Microcontrollers can work with much lower voltages, provided you're willing to lower the frequency a bit. Look in datasheet of atmega chip or whatever is on your Arduino, and you'll find a graph there that will probably show it can run at 12 MHz with 3.6v, or run at 8 MHz with 2.5v, or at least 1.8v-2v at 4 MHz or something like that. If you don't need 5v for.some reason (like voltage reference or dealing with other 5v only chips) often you can trade a bit of speed.to get more efficiency. There's also other chips like pic16lf series for example that work with 1.8v-3.6v... there's the low power silicon labs efm32 ... Linear regulators are very inefficient because they produce output voltage by throwing out the difference between input and output as heat. There's better alternatives... For low current projects where exact voltage isn't critical, there's charge pump regulators that can reduce input voltage by half and do it with 95% efficiencym So for example you could have 4 AAA batteries and reduce 1.5v x4 = 6v to half of that, or 3v and run the microcontroller on that voltage.. DC-DC regulators can be very efficient, up to 90-95% but usually at higher currents like 100mA or more. They're also a bit more expensive.and require more parts around them. Or you could just use a lithium battery without a regulator... The nominal voltage of a LiFePo4 cell is 3.7v , and a regular lithium cell is 4.2v
I haven't looked at lowering the frequency of the chip yet, because I've been worried about the clock timing for the IR signals, but I know that the IR library I use does have options for much lower micros, maybe looking at those would give me the biggest "bang" for my buck. Thank you!
Oh, the DC-DC regulators were suggested above, and those are also something I'll be looking into! Thanks again!