This is Google's cache of http://forum.mysensors.org/topic/183/efficiency-of-1v-to-5v-step-up-module. It is a snapshot of the page as it appeared on 7 Jul 2014 09:42:59 GMT. The current page could have changed in the meantime. Learn more Tip: To quickly find your search term on this page, press Ctrl+F or ⌘-F (Mac) and use the find bar. Home Hardware Efficiency of 1V to 5V step-up module Efficiency of 1V to 5V step-up module Hello everyone, I recently received about half my sensor parts that I ordered; very excited to get things hooked up and running (I have the gateway running, but no sensors nodes yet...waiting for FDTI adapter to program the pro minis). Anyway, in the meantime I've had a chance to test some things, and I have a question regarding the efficiency of the 1V to 5V step-up module featured on the store page. Question: Has anyone else observed that this module has terrible efficiency? My test set: 1.5V battery into the the 1V to 5V step-up into the ground and raw pin of the pro mini (I believe the pro mini came preloaded with 'blink' example). I am reading current into the step-up and the current out of the step-up. My observation: When the LED is in the off state: Current into the step-up module -> 72 mA Current into the pro-mini -> 14.6 mA I was expecting something like ~20 mA into the step-up module, but 72 mA! That is terribly inefficient. Is my copy bad? Has anyone else testing this module and found different results? Can the step-up be modified to be more power efficient? I know the power indicator LED on the step-up can be disconnected, but I calculate only a few mA (2-3 mA) based on the load resistor and voltage across, so that is not going to be too much help at this point. Thoughts, comments? What about building up a circuit based on the TI TPS61097-33? (of course for a 3.3 V pro-mini version, I have those on the way too.) Thanks, Erik posted Reputation: 6 | Posts: 28 Posts 44 | Views 519 | browsing @therik If you have USBasp, or other arduino you can program Arduino mini without FTDI adapter:) posted Reputation: 3 | Posts: 63 @therik As the Voltage changes, so does the current. You need to look at the power consumed/lost to work out the efficiency. Assuming LED is off then: Total power in: 72mA*1.3V= 93.6mW // assumed battery is actually more like 1.3V under load Power consumed by load: 14.6mA*5V=73mW Efficiency of power supply unit: 73mW/93.6mW= 78% More detailed measurements may give a different figure but the approximated efficiency looks reasonable. posted Reputation: 1 | Posts: 21 Hi, Agreed. The end goal, of course, is to realize a battery power sensor that lasts ~1 year. I plan on sleeping the sensor according to the great work you have already done, but still I worry about the current draw of the step-up. I'll chill out and wait to properly program the sensor nodes and report back regarding the my results. Let me say that this is a great group, and this is the most practical thing I've learned since my PhD in EE. I hope that someday I can also contribute something. posted Reputation: 6 | Posts: 28 Run two batteries in series and use a 3V3 processor running at 8 MHz (or lower). I found these to work well: https://www.sparkfun.com/products/10967 As for the PhD - I hope it had a title that no one understood whatsoever. That's essential ;--) posted Reputation: 1 | Posts: 21 @a-lurker said: https://www.sparkfun.com/products/10967 I just found this AA power board: AA Power board posted Reputation: 2 | Posts: 100 Yea, I was thinking about trying the Sparkfun board. The other option is cool, but perhaps a bit pricey. I'll order the Sparkfun board and do a comparison to what I already have. When you say run off of 2xAA, you mean directly into the pro mini, right? Not a bad option, but my eventual plan was to hack a $1 solar light to recharge a single NiMh battery. If I go with two batteries, I'll need two 3-cell panels...at which point I could charge 3xAA but then would need to step down the voltage (diode would work) to run the pro mini. That being said, I've heard bad things about trying to charge more than one cell in series; which leads me back to a single battery and a step-up. Or go with a LiPo and two 3-cell solar panels. Thoughts? Dissertation title: Quantum-well Intermixing for Wavelength-Agile Photonic Integrated Circuits. Thanks, Erik posted Reputation: 6 | Posts: 28 @therik the problem with any rechargeable battery is a limited number of charging circles especial with ni-mh/cd batteries you will get "memory" effect with continuous charge without special logic of charge/discharge your battery will run out of life circle very fast while you have a solar it is better to use 2 or 3 sources of power 2 sources is a solar directly and alkaline as a backup power etc the priority circle is solar -> battery with 2-3 cells you can run MCU directly from batteries while decreasing frequency to be not higher than 8mhz with 1 cell you can use modern step-ups with very low quiescent current (like mcp1640) 3 sources will have a priority: solar->super capacitor->alkaline battery in this case you add super capacitor as a second priority source super capacitor can be charged from both solar and alkaline or only from solar you should use electronic switch to activate alkaline only if voltage on super capacitor will drop bellow acceptable level (about 2.7-3v) all this supported by good usage of power saving modes of your MCU will allow you to run for years, etc. more longer than with rechargeable batteries because rechargeable batteries with every day charge will get out of life circle in less than a year sense and drive posted | last edited by axillent Reputation: 3 | Posts: 57 @therik I used to think that you could run the MySensor stuff just using two batteries connected directly to the processor but came to the conclusion that's a bad idea. First, to get the best out of some sensors running them off a fixed Voltage is preferable. Secondly two alkaline AAs supply about 2.4V to 2.6V (during most of their operational life time) and the 3.3V CPUs have the brownout set to 2.7 V (typ). So if you use this method, you need to ensure the brown out detector (BOD) fuses are set to disable the brownout detection completely. Doing it in software is not sufficient, as the BOD is automatically re-enabled as soon as the CPU comes out of sleep. The CPU spec shows the maximum Frequency vs. VCC line for between 1.8 V and 2.7 V. The line equation is Vmin = (F-k)/m, where from the spec k = -8 and m =6.6666 so for 8 MHz: Vmin = 2.4V Towards the end of their life two AAs will go below this Voltage. What happens then? With an inverter you can monitor the battery Voltage and trigger an alarm when it gets really, really low. Also with the inverter you can squeeze every last ounce of juice out of them and everything will still work. mmmmm - Quantum well - still trying to picture that one - is that like a hole in the ground or you like your quantums well mixed? The title must be totally incomprehensible - that's the first essential step towards achieving the award. @axillent Totally agree about charging batteries - probably more hassle than it's worth. Depending on the application, just solar charging a super capacitor could work well. Imagine a temperature sensor reporting back every fifteen minutes and it consumes say 30ma at 3V3 for 0.5 seconds while it reports and we use one of these: https://www.sparkfun.com/products/746 time roughly = (C/I)*(Vmax-Vmin) so say we use say a Vmax of 2V and Vmin of 1V and use that to power an inverter to 3V3. Also assume we draw 100 mA at 1V, which is about 30 mA at 3V3 for the CPU and radio. We have a ten Farad cap but it's a bit out of tolerance, so it's actually only five Farads. (5/0.1)*(2-1)= 50 seconds That allows for one hundred 0.5 second samples to sent before the cap is "flat", which is 25 hours if sent every 15 minutes. So it looks like it could work OK. Should work for @HeK in Sweden where the shortest day is only about 7 hours long, with the main problem is keeping snow off the solar panel. posted Reputation: 1 | Posts: 21 @a-lurker said: Should work for @HeK in Sweden where the shortest day is only about 7 hours long, with the main problem is keeping snow off the solar panel. smiley posted Reputation: 21 | Posts: 419 @a-lurker Good idea with super capacitor. I will try this to power well water level sensor. I am planning to power this capacitor with cheap solar panel, and report water level every 60 minutes. Theoriticaly it should last about 2 days without sun. posted | last edited by jendrush Reputation: 3 | Posts: 63 Lets not mess around - how about using a 3000F capacitor?? http://www.ebay.com/itm/3000F-2-7V-Maxwell-BCAP3000P-super-farad-cap-ultracapacitor-/251464140905?pt=LH_DefaultDomain_0&hash=item3a8c6e4869 If 10F is about 25 hours then here we have 300 days - nearly a whole year. That will solve any problem @hek might have with short winter days (capacitor leakage may be issue and the price? - what the hek). But seriously, need to ensure the capacitor is never charged with a Voltage higher than its rating - typically 2V7. Three solar cells in series feeding the cap with a Schottky diode might do the trick. A fuse inline with the cap makes sense as well. posted Reputation: 1 | Posts: 21 I have done some measurements several boosters. Here are the results. Sorry about the legend names. Booster_Graphs.jpg posted Reputation: 6 | Posts: 28 Interesting - have you got schematics for all three or URLs for them? The Chinese ones are not so good - what ICs are they using? Also the Sparkfun device seems to draw about 500 uA with no load. It's a little higher than I would expect. Certainly would not want it to go any higher. posted Reputation: 1 | Posts: 21 @a-lurker Oh, one more thing...these measurements are all for Vin = 1.2 V All these have a bit of trouble supplying current > ~19 mA with Vin = 1.2 V. SparkFun Board schematic on the site. And the Chinese ones are the ones from the MySensors store, so...no schematic, and I haven't been able to identify the ICs used. So, the big question is: Do these supply enough current to drive the 'standard' radio? Powering the LNA+PA radio is out of the question. Which leads me to another question: What is the best way to power the LNA+PA radio? I have read your analysis on the 3.3 V output of the Nano, not enough current; so, would powering the LNA+PA radio involve a separate AC/DC converter? and what supply current rating? is 200 mA enough? What buck converter are you using? Thanks! posted Reputation: 6 | Posts: 28 First I'm not using a nano as the ft232rl just draws unnecessary power. So I use one of these: http://mysensors.org/build/battery and one of these to program it. Make sure it's power pin is NOT connected to the CPU PCB. https://www.sparkfun.com/products/9873 Also I use two batteries in series. As you are finding, 1V2 is close to the marginal side of things and this is what you get with one battery. The standard radio works OK with two batteries. In fact, you could probably power the higher powered radio with two batteries. How long they last, obviously depends on how long they are running, versus sleeping. The batteries would die very quickly with continual use. Could always use a couple of D cells. However, I'm hoping someone will try the solar cells and super capacitor approach. It's got a lot of merit. posted | last edited by a-lurker Reputation: 1 | Posts: 21 Does anyone have a source for a cheap 3.3V boost module other than the one listed in the store? 5V modules are much more common for some reason. Bought a couple of those 3.3V boosts but was bummed that they had included a bloody LED on the board. Also skeptical about efficiency as well. Bottom line is that it might be better to build one yourself, but the cost of doing so obviously cant skyrocket and it would have to be almost as compact as the Ebay boost module. posted Reputation: 0 | Posts: 8 I'm happy to switch to some other more efficient model in the store if a good tip comes in here. Especially if it has an led mounted! This looks different (and I can't see any leds). Has anyone tested it? http://www.ebay.com/itm/Step-UP-Power-Converter-Voltage-Module-Input-1-3-3V-Output-3-3V-DC-DC-/281051710512?pt=LH_DefaultDomain_0&hash=item416ffcc430 posted | last edited by hek Reputation: 21 | Posts: 419 @hek Yes, that module looks better. And a smaller footprint as well. Anyway, I guess I can just cut out the LED track on the PCB just like I will on the Arduino? Now all we need is some seller on AliExpress or whatever that sells packs of 10 at a discount. posted Reputation: 0 | Posts: 8 FYI: Following some links after google'ing for the model type on the 3.3V step-up converter IC (2108A) brought me here: https://translate.google.com/translate?hl=en&sl=zh-CN&tl=en&u=http%3A%2F%2Fu.dianyuan.com%2Fbbs%2Fu%2F81%2F1185241253594082.pdf The LY2108 seems to be th step-up converter from the module in the shop... posted Reputation: 3 | Posts: 90