Hi, this is Wayne again with a topic “Maker Hangar: Episode 4 – Li-Po Batteries”.
Hello and welcome to maker hanger, my name is lucas weekley and today we’re going to be talking about lithium, polymer or lipo batteries. These power rc models so obviously they’re very important, we’ll get into some safety how to charge them and some other topics. So let’s get started, there are several numbers that classify a lipo battery the milliamp hours, the c rating and the cells of the battery. The milliamp hour rating is how much power can be stored inside of a battery in relation to time. So a 2200 milliamp hour battery running at 1100 milliamps will run for about two hours.
Now, of course, an rc plane will draw much more power out of a battery than this example. The c rating or capacitance rating is the measure of how much power can be dumped into something. At a certain time, say we have a 20c battery, that’s not going to dump very much power into something, and it’s probably not going to be able to support a powerful brushless motor to power. A high kv motor a battery with 30 to 35 seats would be sufficient, any less than the motor would be less responsive and it would take a while to update for powering your receiver or your transmitter.
A battery with 15 to 20 c’s would suffice. Finally, the s rating, which is how many cells a battery has all batteries are made up of cells and lipos are no different. An individual lithium polymer cell has a base voltage of 3.7 volts when fully charged. It is 4.2 volts.
So by using this, it’s pretty easy to figure out the rest of the voltages for different batteries. 3S batteries are the most common. This is because there’s standard voltage around 12 volts. They are labeled at being 11.1 volts, but when fully charged they are around 12.6 volts. Apart from planes, 3s batteries can be used in transmitters and other electronics that don’t fly. There are also 2s batteries with a charge voltage of 8.4 volts, and these can be directly connected to some receivers and also power. Other electronics, 1s batteries are used for microplanes 4s batteries are used for speed planes and the cells of a battery can go up to 12 or more or anywhere in between, because of the combinations between milliamp hours c ratings and cells. Lipo batteries can come in tons of different shapes and sizes, and now you know what to look for the lipo battery is the heaviest part of an airplane.
So that being said, it is used to balance the plane. So say your balance. Point on your plane is slightly back. Well, then, you can move your battery slightly forward to balance out your plane. Normally you never want to add weight to your plane.
You just want to move around the battery to get the proper balance. There are two sets of wires coming off of the lipo battery. The first is the main wires.
These are two large diameter red and black wires, and they go to a connector. Never let these two contacts touch if they do it’ll damage the battery. We’Ll talk about safety in a couple of minutes, and then you have the balance port, which for a three cell, has four wires coming off of it, but it depends on how many cells you have for the wire count on these. This is just a direct connection to the individual cells of a battery. The balance port is plugged into the charger which can then balance or charge the individual cells so that the battery can maintain an equal voltage which is important to let a lipo have a long life. So once you’ve got a flight with your plane and your batteries are drained now you want to charge them and when you charge batteries you always want to balance them. The charger i recommend is called the accusel6 and you can find it in the parts list. For this series, it’s a programmable charger and it has some built-in safety features if you’re using any lipos.
I recommend you get a programmable charger. Now, these all pretty much have the same software. So let me walk you through how to charge a lipo. Here’S the accusel 6 and it’s plugged into the compact power supply over here, of course, so we’re at the main menu right now and you can cycle through a couple of the different options.
Uh there’s a couple other ones on this menu, but we want to find program select lipo battery. This is what allows you to charge a lipo battery, so we’re gon na hit, select or enter we’re going to get this prompt. So we have up in the top row, is lipo charge. Now these buttons, the plus and minus, allow you to cycle through different options and then the select allows you to select them.
So you can change them and then the stop button allows you to go back. So we’re going to hit the plus button on let go charge, since there is nothing flashing, then the top row is selected, so you can get the lipo balance like we talked about before then there’s lipo fast charge which, when you’re charging a lipo battery the topping Off part of it or charging at the end, that takes the longest time, so this just skips that so you can get to the flying field faster. Then you have lipo storage, which brings it back to its original voltage of the cell. So you can store the battery safely, then you have lipo discharge.
This is, if you charge your battery too much and you want to get some power out of it. Then we have lipo charged like we saw before that’s just plugging in this connector. You discard the balance connector and it charges all the cells at once now that can be a little bit dangerous, it’s okay for a couple times, but you always want to balance your battery. So, let’s get into the balance now we’ll set up the battery for this battery, so i’m using a 2200 milliamp hour 3s pack, so we’re gon na hit select see this is flashing.
This is our c rating for the charge. Now what you want to put on this is the amps. So this battery is 2.2 amps and if you didn’t have that number on it, you could take your milliamp hours, move the decimal place over three spaces, and now you have your amps.
So we’re going to match that number on here that’ll give us a 1c charge rate now. This is what you always want to charge. Your batteries at most batteries will only charge at 1c. Now some high voltage batteries and some more professional batteries they can charge at two c. So if you had that, you would set it to twice that value, so that would be 4.4.
That would be two c’s. Now i’m not going to do that because, even though it can handle it, it’s not very safe, so go back to 2.2 yep there. It is now we’re going to cycle over to the voltage. This is a 3s lipo pack, so it’s 11.1 volts.
So we’re going to see that it’s 6s – that’s not right, of course, so we’re going to back it up all the way to 3s 11.1 volts, and now we have everything set up for our battery. So for the connections, you have the main lead. You have to plug this in plugs in here and then you have the balance port, which plugs into the side and its corresponding port, and you hold down the start button. It beeps just checks the polarity of everything and then, when it says it’s clear you hit enter and now it starts charging the battery.
Now we have a couple things that we can go over while we’re in here you can see the charge rate now. This will progressively slow down as your battery gets closer to being fully charged. You have your voltage of this back right now, then you have your setting, which is balance, of course, how much time it’s already taken and how many milliamps you put into the battery. If you hit, plus you can see the individual cells hit, plus again you go back to here. You can come back and see the end voltage, which is 12.6 volts. That’S when it’s going to stop charging it, and you have a couple other things like the cutoff is going to end up at 5000 milliamps to put in to the battery. If it exceeds that, then it’s just going to stop and also if it exceeds two hours of charging, then it will stop.
And then you can also plug in a temperature sensor and attach it to the battery just to make sure it’s not getting hot and then it’ll stop once it gets to a certain temperature. If that happens, so that’s it now, your battery’s charging, you just wait for it to end and it’ll just beep at you and you unplug. It don’t worry about it over charging once it starts beeping, it’s done charging and it’s not going to put any more power in the battery and that’s it now.
Let’S talk about the safety of these batteries, so to start off with. Why are we even talking about the safety of lithium polymer batteries? Well, some have been known to explode. This is only because of the misuse of these batteries and just following some simple safety rules and not being irresponsible with them. You can prevent any mishaps from happening. That being said, it is very difficult to have a lipo battery explode and if you just follow these five simple steps, you’ll never have one blow up on. You always know your polarity. If the wires on a lipo battery get switched while charging, it will ruin the battery and it might explode. This is one of the only ways you can make a lipo battery explode, except for physically damaging the cells. When we solder up the connectors in a later episode, i’ll explain what to look for with the positive and negative ends of the connector.
Luckily, programmable chargers will detect that the polarity is wrong and not give the battery any power never charge too fast. If you’re charging at a c rating that’s higher than what the battery is rated for, then you can damage the battery. Some batteries can charge at more than two c’s, but it’s better to be safe than sorry and always charge your batteries at 1c.
Getting out to the field faster is not worth the risk. For this reason, you always want to watch your batteries, while they’re charging occasionally go and touch them and make sure that they’re not warm if they are immediately take it off of the charger when you’re flying. Never drain the battery all the way down when your esc starts to slow down. That means it’s regulating your input to warn you that the battery is running low land the plane. If you drain the battery down all the way to zero percent, then it will damage the battery. All the individual cells will begin to puff up, and the life of the battery will be a lot less. If you happen to drain the battery down all the way to zero, put it on the charger immediately, this can help save the battery. Finally, once you’ve charged your batteries store them in a safe climate, controlled area, which you can monitor, occasionally check on them to make sure that they’re, okay, so far in this series, we’ve talked about how to give your plane thrust. Well, that’s not any good! If you can’t control it, so servos are little motors that move control, surfaces that control your plane and we’ll talk about those next time. Thanks for watching .