Hey guys, my name is Sam, and today we're going to take a look at how to choose the lipo battery for your next project. So as technology continues to develop and more and more devices of becoming portable we've got an increased reliance on batteries and we've got these wonderful battery technology known as lipo which is short for lithium polymer batteries or lithium ion polymer batteries we're going to stick with LiPo today so if there's a few different things we need to understand and if you're not sure what Lipos are or how to integrate them with your projects and we've got some separate tutorials on those for using lipos in your projects and some chargers and products that are going to help you use those, but today we're going to take a look at some of the specifications and key points to look for when you're when you're choosing a battery for your next project.

So the first thing we want to be aware of is at what the cell is, so lipo batteries are made up of cells and most batteries are going to be made up of a single cell, and a cell is a bit like a smaller battery, you know, lower level battery inside of the battery casing that you have here. So as we said most batteries are single cell batteries and they are known as 3.7 volts nominal charge batteries we will get to voltage in a moment but you can get batteries which have a higher voltage because they have multiple cells in there so you might see packs that have 2S or 3S written on sorry, 3s written on them and that stands for two series or three series, S stands for series that means they're multiple cells wired in series which of course the voltages add together to give you a higher nominal voltage battery so we're talking about voltage with a nominal voltage then that's because with voltages you've got to be a bit careful with lipo batteries, so we refer to a cell as 3.7 volts but when you fully charge your lipo it's going to rest at about 4.2 volts maximum charge and when it's fully discharged it's going to be around 3 volts and you should never exceed the limitations, otherwise you can cause damage to your lipo potentially cause it to overheat, swell, or catch fire, gotta be safe when you're using lipos!

So a good quality charge won't allow it to charge over 4.2 volts and likewise if you've got some sort of protection system in place it can trigger when your cell voltage gets to the 3.2 or 3.1 mark and you know you really need to recharge your battery so that voltage and you know of course if you have the three cell battery then the normal voltage might be at 11.1 volts is going to be higher when you, when it's fully charged and lower when it's depleted. Then the biggest thing that's going to impact your project is the battery capacity and this is directly related to size the bigger the battery the more charge it can hold and capacity is measured in a unit known as milliamp hours, so you have heard of milliamps perhaps or amps, milliamps is a subunit of amps which is the amount of energy flowing at a given point in time and milliamp hours is the amount of charge that it can store before it is depleted so what is what a milliamp hours mean? Well take this guy it's a 1000 milliamp hour lipo battery and that means that it can provide one amp or one thousand milliamps for one hour before it's depleted, it could provide 500 milliamps or half an amp for two hours before it's depleted and so on and so forth and it could provide, providing the battery is able to deliver that much current which we'll get to in a second, it could provide two amps for half an hour. So you can apply that to all of the different battery capacities there and I put a formula to calculate the time and the power that you can draw from the lipo before it will be discharged down there so take a look at that if you want to work out exactly how much you know how much life your battery is going to give you a project once you know the average current Draw of your project.

Now the discharge rating is particularly important both for safety and to preserve your lipo so discharge rating obviously refers to the current that it can discharge at any given point in time now there's a special rating known as the C rating where C is multiplied by the capacity of the battery and that gives you the maximum discharge. So a battery may have a rating of one C for example two would multiply one by your battery capacity and that is the maximum amount of current that it can discharge, so again one thousand milliamp hour battery with the 1C rating could discharge 1 Amp continuously it had a 2C rating that will be 2 amps, this guy here a beefy six thousand milliamp hour that had a 2C rating would be 12 Amps, 1c six amps and so on and so forth it's fairly straightforward and on top of that some batteries will also give you a boost, or you know a burst C rating where you can temporarily for short period of time, draw more current than the typical C rating, but for the most part you want to stick within that C given C rating otherwise you can cause cause your battery to swell up, damage to it, damage to your project as mentioned and also bear in mind that the wires on some batteries may be thicker or thinner, and are capable of carrying less current, so this 1000 milliamp hour battery might have thicker wires than a much smaller battery which is going to limit the currents on some battery pages it says restrict the discharge to one Amp despite the C rating unless you want to replace the wiring harness which I only recommend doing if you really know what you're doing. So that's the charge rating and the discharge discharge rating I should say the charge rating is the exact same thing that how much energy can be charged with at any given point in time it's fairly common sense although charging at 1 amp is pretty recommended now size is directly related to capacity the bigger the battery the more energy can hold the more space it takes up, fairly common sense, I've got a couple of different batteries which I recommend for all sorts of different projects depending on how you're using them you've got your really small 120 milliamp hour battery your 1000 milliamp batteries are stepping up on with ten times the capacity but it's still nice and flat which is good then in between you've got a cylindrical battery this is known as an 18650 cell their designs are sort of like a big double-a sized batteries but they're actually lipo batteries and work in the exact same way but are ideal if you need something that's a bit narrower and need that flat form factor, then again six thousand milliamp hours this guy is really chunky, so six times the capacity of the 1000 milliamp hours here but a bit bigger it does a really good job of powering your you know chunky project if they need a lot of juice and give them a different battery life or just make that project that you've got going to ever without needing to be recharged so that's a bit of an overview about all the specifications of lipo batteries that you need to be aware of and hopefully now you can go on and know what project it is do you want to build and take a battery that's going to best suit that project based on the voltage it needs how long it's going to last and the physical dimensions of the battery itself if you've got any more questions then let us know in the comments below I get the conversation started and we'll see you next time.