When should I retire my LIPO battery?

How'd you know when a battery has come to the end of its life.

Now there are a number of indicators that a battery is getting towards the end of the life that don't last forever, but I thought it would be useful to just put this together for those of you that might be new to this topic, to let you know when it's time to retire one of these. Pushing a battery too far will ultimately mean that you will probably end up having a crash because when you think there's still energy in the tank, there won't be because the battery is too old.

So let's cover a couple of basics first before we get into how you can spot when a LiPo battery has given up the ghost or about to anyway. Don't forget the Lipo battery the usable voltage is between 3.5v per cell and between 4.2 or 4.35. If it's a high voltage Lipo, that is the usable range

it's actually quite a short little range. So don't ever discharge it below about 3.5v per cell. I try not go below about 3.7 or 3.6 volts per cell because, just gives me a little bit of wiggle room.  

My second point is never overcharge or over discharge a LiPo battery, going above that voltage or below that voltage will cause it to age quicker, probably won't result in it, just exploding despite what you might see on YouTube. However it will shorten the life.

I also wouldn't recommend leaving your life of actually charged 4 weeks at a time. It's fine to leave it 4 or 5 days if maybe you charge it on a Monday, and you want to go fly, but you don't get out to flying it that weekend. It's not gonna really upset it. However leaving charge for months at a time is going to eventually cause chemical changes within the battery, that is going to affect his performance.

So whenever you finish flying, bring it back and take it down to what's called the storage charge, most battery chargers have them or you can use this very specific battery discharger to put it to that level, and that's normally about 3.8v of cell, consider that for months even years at a time.

Last couple of tips on Lipo general safety and good practice is never leaving a charging lipo unattended, always be in the same room. All the horror stories you hear of people having their houses burnt down, because they're not using a lipo safe bag and they left the battery unattended. That's by the point, Lipo safe bags they're not there to contain the fire, although they will if something catastrophic happens with batteries, it does happen very rare. But you know when it's happening in your house or garage the lipo safe bag's job is to allow you to pick it up and to throw it outside before it sets anything else on fire, its job is not to contain the total fire because lithium is one of those metals that once it gets lit, it likes to burn.

The last tip is always charge a LiPo battery at the level that it says on the label . If it doesn't say anything then it's reasonably safe to assume it's 1C, and what that means is something like this 2.2 or 22 milliamp power pack, that means I need to charge it at 2.2 amps. So that is the charge level that I'm setting if I'm not in a rush, I'll be nice to the battery and I might set it at 2 amps or 1 and a half amps, it will still get charged, it will take a little bit longer, but the battery will thank you for it. Some batteries can charge at higher C ratings and those that do will usually have it on a label.

So how do you know when a battery is end of life.

1. Puffing of he wrapping or case. If it's pretty severe then it'll look like one of these these are two of mine that have come to their end of life, and they didn't look as bad as this before I completely discharged them completely discharged them have caused some irreversible chemical changes within the cells, that have caused them to puff up. It's essentially little gas bubbles that is causing the cells to puff up and look like this.

If any of your batteries look like this and you are using them, my advice would be stop discharge them destroy them go and recycle them, it isn't worth risking your model. However batteries don't have to look like that in order to be coming to the end of their lives, some of them might be in hard cases, might be harder to see. And I've had batteries that have just started to misbehave that don't look like some of these took a straw in the end and try and blow them up like a balloon.

2. Internal resistance starting to change. One of the big giveaways is the internal resistance is starting to change most modern chargers will have the ability to monitor the internal resistance of the batteries, most of the time we never even look at that. However I do check it every time I put a battery on charge just to make sure that the numbers are all reasonably the same they're not completely out of whack, or one isn't completely different. So say for example this is a 4s lipo battery, maybe two of the cells are 6 milliomes one is 8 milliomes, and one of the cells is suddenly 22 milliomes, that's an indicator that that cell is very unhappy and probably on its way out. That will be shown in a couple of other ways if you're not monitoring things like the internal resistance of a battery lots of us don't. First and foremost is every time you come to plug it in or check your Lipo, the charger says the pack is unbalanced if it's regularly doing that, then that's an indication that one of the cells, one or more of the cells inside of it is at the end of its life, and it's basically going to mean the whole pack is us unless you want to start taking things apart and soldering stuff which unless you're very capable I wouldn't recommend.

3. Spends more time on the changer in the "balance" phase of the charge. The other dead giveaway is that when you go to charge it on your battery charger and you put it in balance charger, it spends hours in that cycle as the charger desperately tries to get those lazy bad end of life cells, up to the same voltage as the others in the pack. If you find packs that are spending a long long time in that final balancing phase of the charge, I would stop and go and check the internal resistances, because it's probably an indicator that something is going on with the pack and they're getting towards the end.

4. Lacklustre performance in the model. In the other big giveaway is lackluster performance if you used to get 10 minutes out of this battery on that particular quad and you go out flying and after 7 minutes it's starting to feel really sluggish, that's also an indicator that the battery is probably coming to the end of its life.

How long do batteries last in practice, well if you take care of them, you don't over discharge them, you put them in storage charge, you take care of them and look after them, and they're good quality batteries, they can last several years, you even can get three four or even five seasons at them. If you're not punishing them, some pilots use batteries like consumables, cane them and they just kind of give up the ghost. If you take care of them they're an investment in the hobby, they can last a long time.

If you see any of the above things that I've talked about with one of your batteries, my advice would be stop and check it, and if you are not sure retire the battery, don't go and fly on a battery and risk your model, your GoPro or action camera whatever it is, or flight controller that battery that's in the model, it's quite a bit of money when you tot it. It's not worth risking it for the sake of a 340 pound battery, I would potentially replace your battery and get one in that's going to give you that 10 minute flight time that used to, you've got on your timers set for.

Last part of the blog because I know I'm going to get asked about it is well how do you retire a Lipo.

The first thing to do is to check in your local area, how your local authority or council or government actually want you to discharge of these things there might be special places to drop them off, they might have special areas, just quick look into and search will find the answer. Most recycling centers want these cells to be dropped off with no voltage no charging them at all, and to take the charge out you've got two options lots of modern charges have a destroy setting as bad as it sounds, where it will basically you plug this in, and it will run the battery down to no volts or cell. So well below that three and a/2 volt minimum that I was talking about before the other way that you can do it is for 2 to 4s batteries. I just plug it into a little light bulb from a car and leave it on my log burner for a couple of days and at the end of that it's completely flat and safe to go for recycling.

If you see your batteries starting to puff up, it's a sign that their end of life.
If you start to see them with one of the cells having a much higher resistance than the others and didn't use to, that's an indicator it's on its way out.
If it spends a loader time in the balance charge and it's continuously unbalanced after a flight, that's also a bad sign too.
But do recycle these, it's very easy to just take all the energy out of them, just connecting a carb light bulb on a 2 to 4s light bulb will run it down to nothing. Again always do that on something outside like a log burner. So if something catastrophic does happen is in a place where it can burn safely and also use things like a lipo safebag, and never leave a charging lipo or a discharging lipo unattended.

 Check out the full video here