Discharging AEP Lipos?

[shadowfacex]

I only get to play once a month and I've never had a lipo go tits up from leaving it fully charged. In fact the only time I've had one stop working was when I discharged it too much 

☝?This. Most LiPos are designed to retain optimal performance around 70-80%, when you store them at this level.

Unless you want to decommission your battery, I suggest you keep some juice in it between games, and charge them fully before each game. This should give you the best compromise without consciously trying to “optimise my battery’s life at the cost of being constantly on edge.”

Average lifespan of a lipo is about 3-4 years, depending on the storage conditions and number of cycles put through it. Some will start to puff a few charging cycles in (like shitty Nuprol ones) or it may last you 5 years when on good terms.

I recently had to buy a spare one and realised my current mini-stick has been with me through 4 years and my charger shows me still about 85% capacity available.

So yeah, don’t waste time on magic tricks and keep it simple. Unless you go through batteries like tea or coffee, then there’s no point in overkill.

Also, invest in a really good charger. ISDT does marvellous gear for RC/Airsoft.

well batteries ain't too expensive and replacing them isn't exactly a difficult task, trying to eke out the maximum number of years service isn't worth anywhere near as much as it would be for say an electric car, where such worries about increasing charge rates etc are very much relevant.

Exactly. If you were to fork out £6k for a battery replacement (cheapest battery for Renault Zoe), or £12k (BMW i3), or just scrap your car because fuck paying £30k for a replacement (Tesla), you’d think about charging cycles.

Paying £20 for a good RC battery once every few years is par for the course, so don’t sweat it.

 

[Lozart]

Thanks, that's the first time I've ever seen anyone actually provide an explanation for why you shouldn't leave a lithium battery fully charged.

On the other hand, every other lithium battery in everything else that I own, including the laptop I'm typing this on, gets kept at 100% as much as possible. Why come none of them have gone critical?

Do you have a reference for that?

Different battery chemistry though. Not all LiPo batteries are created equal! If you abuse a phone battery or it's poorly installed you can still get 'splodey nastiness!

 

[Cannonfodder]

Different battery chemistry though. Not all LiPo batteries are created equal! If you abuse a phone battery or it's poorly installed you can still get 'splodey nastiness!

Just ask Samsung Galaxy Note 7 owners

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[Gonz.]

Do you have a control group against which you're comparing?  Or a reference?

Really, I've seen this asserted over and over, but not once have I ever found or been shown a citation for it, that's not itself just more assertion.  I'd love to read one.

@Rogerborg I understand where you're coming from. I'm no scientist and am not out to prove my opinion to everyone's satisfaction. However, I have seen you in a similar situation having your advice/opinion questioned by someone asking for non-anecdotal evidence of your opinion, when it's clear that you have a lot of experience relating to airsoft and you share your experience to help others. Having learnt much from many of your posts in this forum, I am taking your question as genuine interest rather than taking exception to being asked if I have a control group. 

So, I'm just sharing my opinion based on experience and bits of information I've picked up over the years. Apart from a general interest, I have 20 years experience in IT and 35 years experience in RC cars, helis, and drones.

Also, I did say it's not really a huge consideration when we're talking about  £10-£20 airsoft batteries, but it's general advice where lithium batteries are concerned.

Whilst I don't have a scientific control group, I have experience of hundreds of laptop owners whose batteries deteriorated in short order and I don't recall a single one that didn't leave their laptop plugged into the mains all the time. This includes my wife; I think I replaced at least 4 batteries in 2 different laptops, before she finally got the message not to leave it plugged in all the time. I haven't had to replace any more laptop batteries at home and my wife still uses my old Samsung Galaxy S7 Edge which I bought soon after launch in 2016, so about 5.5 years on the original battery. 

Like someone said to you once, this is just anecdotal, but I'll link some references below.

Most consumer devices will charge a battery to 100% and the good ones then cut power until it reaches 95%, then top up again. Some will keep the charge at 100%. Neither is great for battery life. 

Now, overcharging/discharging, fast charging/discharging and high temperatures will do more damage to lithium batteries than just holding a 100% state of charge, but 100% SoC causes degradation, particularly at higher temperatures.  I have to add that degradation from maintaining a high SoC does not directly equate to 'splodey nastiness as @Lozart so eloquently puts it ?, it just degrades the battery. 

As far as a citations go, I can't find the study I read about battery care in deep space exploration vessels, but I found this NASA document, "Guidelines on Lithium-ion Battery Use in Space Applications" states "The state-of-charge (SOC) and temperature at which the cells are stored or cycled greatly affects the irreversible capacity loss in the cells."  https://core.ac.uk/download/pdf/10549369.pdf

When someone asked Jeff Dahn how they might make their EV battery last 10 years, his response was to charge to 70% normally, and 100% only if needed for long trips. Jeff Dahn is a Professor of Physics and Atmospheric Science, Tesla Industrial Research Chair and as one of the most renowned battery experts in the world. https://insideevs.com/news/334778/tesla-battery-experts-recommendation-for-maximum-battery-life-video/

Beatrice Browning, a PhD researcher at the Faraday Institution, states ". . . leaving a LiB-powered device plugged in overnight is still damaging to the battery’s lifetime . . ." https://airqualitynews.com/2021/01/12/why-do-lithium-ion-batteries-degrade-over-time/

This article from Michigan University recommends "Minimize the amount of time the battery spends at either 100% or 0% charge. Both extremely high and low “states of charge” stress batteries. Consider using a partial charge that restores the battery to 80% SoC, instead of 100%. If that’s not possible, then unplug the device as soon as it reaches 100%" 

It also claims "Nokia and Sony mention potential damage to their phones if the device is left charging after reaching 100%".  https://news.umich.edu/tips-for-extending-the-lifetime-of-lithium-ion-batteries/

This article from the Battery University might not be peer reviewed or detail methodology of testing, but is interesting reading.  https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries 

This article goes into some of the chemistry involved https://www.eyerys.com/articles/40-80-rule-battery-charging-dealing-lithium-based-chemical-problems

This article discusses parasitic reactions in lithium batteries and also references Jeff Dahn https://electrek.co/2018/05/04/are-you-killing-your-lithium-batteries/

I hope this helps

 

[Rogerborg]

However, I have seen you in a similar situation having your advice/opinion questioned by someone asking for non-anecdotal evidence of your opinion, when it's clear that you have a lot of experience relating to airsoft and you share your experience to help others

Wut, no, I make it up as I go.  

Asking for citations is just a habit from my day job.  Verifiability is everything, or else you're just operating on faith.

To be clear, I wasn't desbelieving, I really was just after an explanation and confirmation.  Those sources look pretty compelling, thanks for providing them.