Gonz.

@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

It's not always just about going critical. The capacity to hold a charge reduces over time when lipos have a hard life. My laptop, tablet and mobile phone batteries will hold a decent charge a lot longer than yours if you keep them at 100% most of the time, because I don't keep them at a high charge. One of the craziest trends is for devices, especially mobile phones, is to have faster and faster charging times. Each charge cycle reduces the performance of your battery. Fast and superfast charging accelerates this deterioration, but device manufacturers aren't going to lose sleep if you end up replacing your battery or your phone after a couple of years, are they? A lipo battery can last 10 years or more if looked after and I have plenty of batteries that have done 1,000 charge cycles. Now they clearly won't hold the same charge they did when new, but they will still hold maybe 70-80%. As an example, I vape and use 18650 batteries. I charge them to 90% and they get me through a whole day for about 2 or 3 years. After that I replace them and use the old batteries in other devices like torches, power banks or RC transmitters.

I'm pretty chill about lipos in general, but I always keep them at storage voltage when not being used for more than a week or 2 at the most. And I have lipo's that are over 10 years old that work perfectly fine. Things that will reduce the performance and lifespan of a lipo include keeping them at high/full, voltages. In fact, lipos in long distance satelites are never charged to 100% at all. I don't recall the optimal figure, but I believe it's somewhere around the 80% mark. You have to take into account that most of energy stored in a lipo is in the middle range of voltage, say 3.6 - 4.0v. I don't recall exact numbers, but something like 4.0 to 4.2v accounts for something like 5% of storage capacity but 20% of voltage range, and 3.2 - 3.6v accounts for about 5% of total battery capacity. We're not talking about memory effect here, it's just that lipos are not so happy with extremes. That incudes extreme discharge or charge rates (relative to C rating), extreme charge states or internal temperatures. Now most people aren't going to lose sleep over a £10-£20 airsoft battery compared to a 6 cell, 16,000mah lipo costing £180+ or a lipo on a satellite, but a lipo will last longer if charged slowly and not fully charged or kept with a high charge for extended periods. In the real world, an airsoft battery used once a fortnight or so is still going to last a good while; just it will last longer if stored at 3.7 - 3.8v between uses/charge cycles. I've even bored myself now, but to answer the OP question, chargers typically discharge lipos very slowly. I personally have a couple of car bulbs wired in series to discharge lipos faster than a charger will, but still not too high a discharge rate. Airsoft batteries will be fine with a single battery and my rig can split into 2 x single bulb sets for 2-3 cell lipos. Leave a lipo alarm set to around 3.65v and job done.

@RogerborgThanks for the recommendation. If ak2m4 has some ZCI barrels coming in, I may just wait for one of those. @ak2m4 Thanks for the heads up. I'm after a 229mm barrel. @Fatboy40 I didn't think such a small increase in barrel length would make a noticeable difference, so I appreciate the warning. I can wait a month for more stock to arrive, but it's useful information to have on the forum. Makes me wonder what fps I'll get if I stick the 363mm barrel from the Nuprol in it ?

That's great info, thanks. Thanks for confirming your experience is the same. I'm glad it's not just me. So I guess I could go with it as is or maybe enlarge the cutout in the stock barrel. I'm also open to swapping out the barrel and if ak2m4 is due some more stock of ZCI barrels, that might be my preferred option. I have been contemplating getting a 247mm ZCI barrel as it's in stock and the flash hider has enough space to hide the extra length. Otherwise, the gun seems to shoot well. Mine is just curving BB's to the left a bit, which is why I ordered the rubbers. FPS on 0.20's is right around 346 fps average and 7.4v lipo is plenty. Ah, perfect info thanks. I will measure the bridge on the Nuprol tonight.

Thanks for responding. I haven't tested it because I can see the contact area of the rubber does not clear the cutout in the barrel. The Macaron contact area has a triangle shape and it's the base of the triangle that is catching. Consequently it's only the point of the triangle that is pushing down through the cutout and that won't be able to provide a consistent hop. I have 2 new Macaron 60 deg rubbers and both are the same. This is what they look like, which apart from the untidy edge on the inside, seem to be fairly consistent with stock images like the one below. Thanks for the info on having to trim the rubber lips with the ZCI barrel. If you still have the original barrel, would you be able to measure the thin bit of barrel between the cutout and the end?

I've got an M904G and seen some of you mention putting maple leaf macaron hop rubbers on the standard barrel, but mine doesn't seem to fit properly. The protruding part on the inside of the rubber doesn't quite fit the cutout in the barrel. When I push the rubber down through the cutout, the wider end of the protrusion catches on the thin piece of barrel between the cutout and the end of the barrel. If I stretch the rubber on to the barrel a bit more it works fine, but the rubber won't stay there on its own. I've measured the thin section of barrel between the cutout and the end at 2mm and I think the clearance between the rubber inner protrusion and the end of the rubber (on the inside) is about 1.5mm. The rubbers are from @ak2m4 so are genuine. Does anyone know whether the rubbers are out of tolerance or is 2mm of barrel section more than normal? I'm also interested to know if the ZCI barrel has a thinner section between cutout and end. Would appreciate any pointers. Airsoft Dad.

Welcome Tony. I can't help you with clothing, but hopefully someone else can give you some pointers.