#64 What is the Ideal Battery Technology to Power 3.3V Devices like the ESP8266?

creator youtubers here is the guy with a Swiss accent again these days more and more devices and sensors run on 3.3 volt there are many possibilities to power these modules today I want to concentrate on the five possibilities to power these modules for mobile applications and find out which is the best because we all love esp8266 I use this chip as an example according the datasheet esp8266 modules have an operating voltage of 3 to 3.6 volt which is about 3.3 volt plus and minus 10% what kind of technologies do we have to fulfill these needs the first technology is alkaline these batteries have a nominal voltage of 1.5 volt in reality they start at 1.5 and end at about 1 volt here we can use either 2 or 3 cells with 2 cells we are at the low side of the specifications this works with some modules but if we stop operation at 2.5 volts we only used about 50% of the energy of the battery the capacity of an AAA battery is about three thousand four hundred milli ampere hours but if we only can use half this is quite expensive because alkaline batteries are not rechargeable at least according the books if we use three batteries we get 4.5 volt and are definitely way above specs therefore we need a 3.3 volt low drop out or LDO regulator which kills more than 10% of the capacity and at the end of the life the regulator shortens the useful voltage range because it always needs the dropout voltage so the overall loss capacity is in the range of 20% if you want to learn more about LDO regulators you can watch my video number 58 the second technology is nickel cadmium it's voltage starts at 1.4 volt and ends at about one watt most of the time it is about 1.2 to 1.3 volt with two cells we get only about 2.5 volts which is not enough with three cells we get 3.6 volt average which is okay but if we look at the discharge curve we see that the voltage begins at about one point three eight volts three times one point three eight volt is four point one four volt this is too high for the specifications of many modules especially the esp8266 viewers told me that they were able to run the ESP with more than four volt but I had examples which did not run stable at this voltage so this configuration should not be connected directly to 3.3 volt chips and we need an LDO regulator to with a 20% waste the capacity of a nickel cadmium AAA battery is less than 1000 milliamp per hour and they are rechargeable in order to get more capacity we go on to technology number three the nickel metal hydride batteries their voltage curve is very similar to the nickel cadmium batteries the capacity however is more than the double and they are also rechargeable technology number four is well known to most of us it is lipo this technology does not come in a a or AAA packages because their voltage is three times higher and many devices would be roasted if consumer would take them for 1.5 volt types if you look now at their discharge curve we see that they start at four point one volt and then at about two point eight here again we need an LDL voltage regulator to protect our devices also here twenty percent of the capacity is used by the regulator one advantage of this technology is that we get many different packages and sizes especially the Reg angular sizes fit often very good into project boxes recently I discovered another battery technology like vapor for this is technology number five and it is new to me also not many offers exist on Aliexpress compared with the lithium cells you get them in a in 18 650 and also in rectangular packs the danger of mixing them with 1.5 volt batteries is real here their voltage starts at 3.3 volt and ends at 2 volt most of the time it is around 3.2 volt if you do not need high currents this discharge curve fits our needs ideally no voltage regulator is necessary their capacity is smaller than the capacity of the lipo but because we do not need a regulator we also do not lose energy I recently bought for a a sells of 700 million per hours I tested them and all had more than 700 million per hours I also got a rectangular battery with a capacity of 4,000 milli ampere hours of the testing I discovered that it only has 1,700 million per hour so this is another example of fake capacity descriptions to calculate the relative capacity I use a simple formula where available I use a a batteries I use the needed number of cells and at the 20% avoided waste of the regulator if none is needed then I compare the million per hours because with all configurations the device gets about 3.3 volt and uses about the same current so a battery with double D million per hours will also last double the time for lipo I compare the volume of three alkaline cells with a volume of 118 650 the volume of three alkaline batteries is about double of the 18 650 battery the life vapor for batteries have the same size as the alkaline but we need only one instead of three e to power our 3.3 volt device the milliamp per hour is one-fifth of alkaline so we get 60% capacity compared to the alkaline battery and we can add the 20% of the absent regulator and therefore get about 80% summarized we have the following five possibilities to power 3.3 volt logic devices from a capacity point lipo is the clear leader and it is also rechargeable from the point of hassle-free there are two leaders first the alkaline for low-power devices because it does not need any protection or caution you just replace them if needed they also do not explode so if you extensively use the deep sleep of the ESP it could be a good solution second it is the live April 4 for higher power devices where you want the possibility to of recharging this battery can be directly connected to the device without any regulator and I load them with my bench power supply set to three point six volt and with a current limit of 500 milli ampere this is between normal and false charge as mentioned before I even got to connect the batteries which are empty cells with a direct wire from plus to minus these connectors can be used to replace to alkaline with one lifepo4 battery and one connector thanks for watching I hope this episode was useful or at least interesting for you bye

Channel: Andreas Spiess

Views: 224,271

Keywords: Arduino, ESP8266, Electronics, Batteries, List, DIY, EEVblog, esp8266 battery, power, devices

Id: heD1zw3bMhw

Length: 8min 21sec (501 seconds)

Published: Fri Jul 01 2016