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Damnit, the Lipo battery industry needs better standards!
Its a learning experience and a farking expensive one. I knew getting into this avenue of electric truck wasn't gonna be cheap, but holy hell, I had no idea the tech in the Lipo's was so damn picky and unstable in comparison to NimH. Case in point. I slightly puffed one of my Lipos from my second set of SMC Lipo's just yesterday. Yes, in 6 months, im on my SECOND set of $170 Lipo, after I ruined the first batch apparently from running the cells to low with the LVC at to low of a setting and they got destroyed according to Bryan at SMC
http://i100.photobucket.com/albums/m...x/pufflipo.jpg I got lucky and got 50% credit from SMC towards a new and updated cell set from Bryan at SMC and I was a happy camper that they came through for me and I proceeded to be more cautious with my Lipo's and raised that LVC on my MMM to 3.5v to be extra safe. Fast forward three months later to yesterday, I got back from the bash pit and started to charge up my Lipo's like I usually have done so they are ready to go at moments notice when I wanna go bash, its much more convienent for me. I get done with the second pack two hours later and I noticed a slight bulge in the middle of the pack. Hard to tell, but it was easily tellable comparing it to the other pack. My first thought is..... Ohhhhhh Sh----! I immediately called up Bryan at SMC this morning and this what I can remember of my conversation with him: Me: Hey Bryan, this is Bryce from Montana Bryan: Hey Freezebyte! Good to hear from ya, how goes it? Me: We'll, im calling cause I have a big concern on my second set of Lipo's from you guys Bryan: Ok, whats up? Me: Well, i've been babying these packs since I got them, balance them at every charge, raised the LVC to 3.4v.-3.5v and they've been doing very well up until yesterday when I charging the last one, I noticed it puffed slightly near the end of its charge. Its hard to tell, but its definently budged a bit. Bryan: How bad is it? Is it breaking the seal on the outside case? Me: No, not that bad, just the center is raised a little bit if you compared it to the other pack Bryan: Did you just charge them today before you went out? Me: No, I charged them the previous night and let them sit like i've always done, its more convienent for me. Bryan: Ohhh, thats not good for our cells. Me: What? Bryan: Yeah, you don't wanna fully charge up your Lipo's until you're ready to go. The cell chemistry in Lipo's and especially ours doesn't like to sit fully charged for extended periods of time. I"m surprised you haven't majorly puffed up your Lipo's sooner as a result Me: Ohhh crap....now what? Bryan: Well, I would immediately discharge them either via driving or your charge and get them down to 7.4v or even lower. We typically will use our cells in races up until the LVC kicks in or get noticable slower and then will keep them discharged like that until the day we need them and then charge them full. Me: Damnit, I heard something about that but I figured it wasn't a big deal,l its just so much easier for me to charge my Lipo's and have them ready to go when I want Bryan: Yeah, I can understand why and I know some cell makers like Trinity, orion or Turnigy apparently are more forgiving in that area, but ours don't like to kept fully charged for idle periods of time Me: Damnit to hell, so...am I screwed again? Bryan: I wouldn't say that, it sounds like the puffing is very slightly and it may go away if you get them discharged immediately. I can't say for sure without seeing them myself. I know we have Lipo's that have been puffed for months and we charge and discharge them on a regular basis along with racing them and have had no issues. You very well could be fine, but again, dont' quote me on that Me: Damn, well iv'e got winter coming up here and i'm not gonna be able to use my Flux for a few months, so what do I do? Bryan: For our Lipo's, discharge them to around 7.2v area, don't worry about the rated capacity, we go by voltage. Then once a month or month and a half, fully charge and discharge them to cycle the chemicals in the cells to prevent them from prematurely wearing out. Lipo's do not have the discharge issues that NimH do, so if you leave 1000mAh 7.2v alone and check it a two months later, its gonna be pretty much within .1-.2 V from where you left it Me: Arrrgh, this is fustrating. So other Lipo's don't have this charge storage issue. Bryan: They ALL do, some cell makers have their cells be more forgiving for extended periods of full charge then ours do Me: Damnit, another costly noob mistake Bryan: I wouldnl't sweat it too much, just take your packs and discharge them to less then 7.4v is the ideal voltage and keep an eye on them. If the puffing gets worse during the discharge or charge, then i'm afraid their ruined. If the puffing stays the same or goes away, you should be fine, just keep a close eye on them. Sorry to hear about the troubles, we do state how to store our Lipo's on our instruction sheet that comes with all our batteries. Me: Yeah, I kinda read through it but didn't pay it much attention Bryan: So we have noticed, and were in the process of updating that documentation so people have a better idea of how to care for our Lipo's as for what works on our Lipo's, may not work on other brands. Me: *Sigh.......* Well I guess thats what I needed to know then..... Bryan: Again, you should be ok, just keep an eye on them and don't get depressed, well take care of you if they do get worse. We'll stand by our products always and help you and all our other customers best we can Me: Well, thank you very much Bryan, I do very much appreciate your time and energy to speak with me and other customers Bryan: No problem, thats what I'm here for. We are crazy busy at times, but we do all we can to help our customers and backup our products. If you ever have any questions or concerrns about anything, even not Lipo related, feel free to give me a call. That's what i'm hear for and happy to do it for our customers like you Me: *Sighhh* It makes me think about going with the LiFe series of batteries that are more forgiving and easier to take care of, but damn they are expensive and not many choices available Bryan: Yeah, I have heard some good things about them, but I have no personal experience with them yet. Me: Ok, well thanks so much again Bryan for your time, im gonna go get these discharged and hope for the best Bryan: Sounds good, don't worry, well take care of you whatever the outcome, feel free to call me and keep my posted. Me: Awesome, thanks again Bryan Bryan: No problem Bryce, take care! Again, SMC has proven that they are willing to stand by their products and going WAY out of their way to help customers. I don't think I can name any company who's gone to such extremes to please customers before. That being said, I am getting very fustrated that the Lipo industry is NOT coming any closer to standardizing the C ratings of Lipo's, let alone the proper way to charge, discharge and maintain them. It seems like they have left the hobbyists to fend and learn from themselves in regards to this new battery tech and if it costs us *literally* to learn about their traits, the industry doesn't seem to give a rats ass. At times, the NimH industry looks like its in good shape to continue being the firm base for electric RC usage. You can charge and discharge them all you want, they can sit for months on end without having to be messed with and you only gotta worry about temperatures during charging and usage. Sure, they are heavier and don't have the same punch the Lipo's do, but damnnit, you don't have to freaking "baby" NimH like you Lipo and thats what's fustrating me the most. A simple battery is causing most of the angst and confusion in this industry and hobby, along with ruined/damaged ECS's, batteries, wallets and feelings and there seems to be no one who is willing to stand up and say "Enough is enough!" We need all these Lipo makers to agree on a proper Lipo care and usage so we don't have this cluster of varied opinion/ideas/suggestions that changes with every single maker of Lipo! LiFe batteries are starting to look like the REAL batteries of the future. They last longer, can be charged much higher/faster, they dont' need a LVC, they don't explode with over charge/discharge. This is truly what this industry needs, a very foolproof, stable and safe platform to build the next generation of RC hobbyists because lets face it, the diehards will always be a small nit and dedicated group that are willing to put up with the roadbumps of new tech. But its the first time learners, new and curious bystanders watching someone drive and fly and the first time drivers/flyer that will make or break this hobby in the 21st century. Having a battery technology that will advance the usage of RC in all area's that is capable of being powerful, stable, clean and most of all, SAFE and COMPLIANT for the general hobbyist will truly be the best way to help this hobby grow and for people to have safe and reliable fun with their RC equipment. |
had this happen to all of my smc hard case packs these are the 6000mah ones right. I was pissed but what can you do. Only had like 10 cycles on them also
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Anyone uses these LiFe series i've been hearing at hobbyking? Will they work well for Savage Flux's demands? I don't see how the hell Maxamps can charge nearly $150 for the same LiFe battery
http://www.hobbycity.com/hobbycity/s...v=l&sortlist=P |
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That sucks that you are having so much trouble! I run a 3200mah 2s hardcase with probably 30 cycles on it and it is fine. Maybe try some other brands? I leave my lipos charged for a few days at a time semi often and never have problems. |
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i leave all my zippy's, flightmaxes, and turnigy's fully charged...and then when im ready to use them i give them an additional trickle charge to top them off before i run....i've had zero problems with hobbycity lipos...the only time it puffed on me was when i accidentally forgot to set my lvc when i switched from 5s to 4s.. lol..
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I'm waiting for a couple of people I contacted to answer back and if they think it's a good idea, we will finally get to the bottom of this C rating thing for good.
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I've heard alot of varied feedback on SMC Lipos. Their reputation is a mixing pot of indifference.
Their Chemistry isn't the best, that's for sure. As far as allowing a Lipo to sit in a fully charged state overnight, that shouldn't hurt anything. I've read where leaving them fully charged for long periods (weeks or months) will lower the capacity of them. As the capacity drops, so does the maximum continuous discharge rate. The number one cause of puffing is exceeding the maximum discharge rate. This is usually indicated by higher than desireable battery temps. If it gets up to 110 or 120, it's being pushed too hard. But then again, there are exceptions to this rule. Flightpower packs for example, don't seem to mind higher temps and usually run warmer than most. I have used a NUMBER of different brands. The higher quality Lipos do NOT behave this way. I have had a couple of Lipos sitting at storage voltage, that just puffed, sitting, for no reason. Cheap China Packs. Good Chemistry is pretty forgiving. My best advice is: Get off SMC and try a different brand. |
What crap. I've left Zippies fully charged sitting for months w/o issue (not a good idea tho.)
Hell, I still have 10C TrueRC lipos that are several years old that still run well. They even are a bit puffed from drawing too much on them, but F it, a year later they are still fine. So do they give a half-life then on the lipos? How many hours can it be charged w/o self-destruction? 12 hrs is too much, what about 8, 6, 4? Maybe its just something that happens overnight. If charged enough, it has the energy to turn back into a pumpkin? |
IMO, don't buy SMC again. They've failed you twice now. It doesn't matter how good the service is if the product can't perform the way it should.
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I've left Maxamps, Turnigy, Zippy, ParkZone, and PolyQuest lipos fully charged for weeks and even months at a time without damaging them but I just took an E-Flite battery back to my LHS because it puffed (presumably from being left fully charged for too long). I agree that it is much more convenient to charge them when you're done bashing for the day and while you sleep and have fresh packs in the morning rather than sit around for 2 hours waiting for the stupid things to charge.
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Damnit Freezebyte needs better lipos!
Sorry for the loss, I went with MA my first purchase. I learned with the wallet... From most of what I've read about SMC, at least here, SMC is marginally better. They may have the best CS in the world, but CS doesn't always equal a quality product. My #1 choice would be Hyperions, #2 would be Zippys. The cost of the new packs will be forgotten when you stop having lipo issues! |
Its starting to look like im going to hobbyking for Lipos now. Wonder if theres any major differences between turnigy and zippys
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Not sure myself, some other members have had both. Anything 30c and up would be fine I am quite sure. I wouldn't worry about getting 45C crazy, and if you're willing to ditch hardcases you'll have lots more fit options.
About the Nimh's, I have to disagree. The market for them remains for the same reason the nitro market remains... because a moron is born every minute. Those of you who actually enjoy nitro may disregard the previous statement... They are temperamental. And peaky. And nuclear hot when you're done. Go ahead and try some in your Flux:lol: You have a bad frame of reference. That's all. just get rid of them. Do it quick- band aid quick, and it won't hurt much. |
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They have noticeably more punch, run cooler and more mah are returned on the charger. The Pack's I am comparing are Apples to Apples. 4S 20C 5000mah Zippy's 4S 20C 5000mah Turnigy's My E Revo setup: MMM ESC Medusa 36-60-1500kv geared 22/40 using Mod 1 gears. I had to upgrade the driveshafts to Traxxas CVD's, because it kept snapping the stock Drive Shafts. I run a tight slipper. This is in an E Revo. Notice the gearing, this isn't a "light" amp draw setup. I've seen discharge graphs on both the 20C/30C Turnigy's and the 30C/40C Turnigy's. I'm pretty sure they are the same cell. Compare the weights and cell sizes. I also run a set of 30C 5000mah Turnigy's and notice No Difference except the 30C packs come with 8Ga. Wire. Yeah, 8Ga. :yes: The 20C packs come with 10Ga. Wire. The Turnigy's will outperform SMC I'm sure. |
Here's a 3S Turnigy 20C 5000mah discharge graph. It's half of a 6S setup being ran in a Savage Flux.
The Max was 112 amp draw. If you look on the graph at the 112 amp spike, it's holding 11.1 volts. That's 3.7 volts per cell. That's more than 20C. :yes: http://i160.photobucket.com/albums/t...repower20C.jpg |
^listen to that guy^
wow $33 http://hobbyking.com/hobbycity/store..._30C_Lipo_Pack Forgot if you're running 4 or 6s... |
Hmm, I may go with Turnigys then and hell, go 3S this time for that price. I'm stick of paying with my soul for Lipo's and getting the shaft.....
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Be sure to watch your temps on 6s. You will actually be increasing the wattage being put out by the motor therefore increasing the heat it's putting out (it's not 100% efficient, afterall). If you can swing the cash, I'd go with 4s and 6s so you can have insane power when you want it but you can also tame it down to a more reasonable level.
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The Red Line is Amp Draw. Each Red Line Spike is a stab at the throttle. The Blue Line is pack volts. The numbers on the right side are amps. The numbers on the left of the graph are for volts. Pick a Red Spike on the graph, then go to the right to see how many amps that spike peaked at. Then under that same spike, see how low the blue line goes, then go to the left for the voltage value. For each amp spike, you can get an idea of how the pack held voltage under the load. I hope this makes sense to ya. |
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Hey Unsullied. How's that Medusa 80mm holding up? |
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Hey Freeze - did you adjust your gearing after you changed your diff's?
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From reading the other thread on pinions, I would say no.
The BP diffs are 3.22 vs 3.42 stockers. Not huge, but enuf. |
THAT'S BS...
one of a lipo's well renouned features is the ability to sit fully charged for weeks on end and still be ready to go!! nimh's cant do that nor can nicd's....but lipo's can hold their charge for years on end, but anything more than a month would be a little silly IMO. |
There is a blurb at batteryuniversity that says keeping lipos at elevated voltages promotes cell corrosion on one of the plates. It was actually for Li-Ion, but the technology is similar. If I'm not running them for a week or more, I keep them at around 3.8v/cell, which is between 1/2 and 3/4 charge. I figure at worst, I have to charge them a little while the night before to top them off.
But having them puff after on;y a night or two at full charge? I'm gonna call shennigans on that one. Chances are, they were just overdischarged despite whatever their labels say. |
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It is well documented that storing packs at full charge will increase the internal resistance and decrease the capacity of the pack. Kokam had some white papers on this floating around the internet years ago, but I cannot find the link right now. I believe they said that storage was anything over 24 hours. This is why most newer chargers have a "storage" or "50%" charge/discharge setting, and when you buy packs they are generally around 3.85 V/cell. This is considered the "optimal" storage voltage. In Kokams paper temperature also played a big roll in loss of capacity. Storing your packs around 45*F will also increase the life of a pack. Placing your pack in a ziploc bag and putting it in the refrigerator works fine, as long as the pack does not freeze, or get below 32*F.
Whether sitting at full charge will cause a pack to puff or not has not been well documented, as far as I know. I do have a few packs that have puffed from sitting fully charged from my early lipo days (Around 2005) when I did not know any better. These packs that puffed are from various "high end" and "low end" companies. Right now I have approximately a dozen companies, and over 100 packs. They are used in all types of RC and also non-RC applications. I also still use some of the packs from those early days for low draw applications, such as receiver packs. Now cell chemistry does have everything to do with capacity, cycle life, discharge capacity, and puffing. Let me start by saying I am not trying to put SMC down in any way, but SMC seems to be having some problems with their newer cells. I have some of their older packs that perform very well. But I have seen lots of their pack either puff or have other problems with a relatively low number of cycles lately. I work at a LHS and we do sell SMC, Thunder Power, Hyperion, Dynamite, Orion, Venom and other packs, so between my own packs and packs we sell, I do get to see how all the packs perform. SORRY for the long post and rambling post, but I do feel that there is many things that can be done to maximize the life of lipos. And I do feel that SMC may be right in saying that storing their pack even for short times at full can cause them to puff due to the chemistry of their cells. It could also be from many other factors, temperature, over-discharge even though your cutoff is set at 3.5 V/cell. Just a note, I have some TP 40C packs that need a LVC of 3.6-3.7 V/cell just to keep the discharge limited to about 80%. Again sorry for the long and rambling post, but I'm just trying to put some of the things I've learned about lipos over the years to good use. If I find time over the next few days I may write a nice long and detailed post about lipos since I see soo many questions about them on here, and every other forum. |
Another thing is maybe don't charge to exactly 4.2v/cell. I set my CC/CV threshold on my charger to 4.15v/cell. You lose very little runtime but that extra 0.05v/cell gives you a little wiggle room in case the balance is not perfect. That way, there is less of a chance for a cell to exceed 4.2v by the end of the charge.
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I've been storing a few of lipo packs I don't use anymore fully charged for a few years now just to see if this claim is correct. Well, none has puffed and I even charged a couple and ran them. Well, they still performed the same way they did before I stored them. A couple of the packs doesn't have balancing wires on them and no problem at all. I hardly balance any of my packs and none have shown any sign of puffing. Now one pack that I don't use anymore is composed of many cells and that packs has been stored fully charged for almost 3yrs now. I only check the voltage to see how far it has drained and it is at 12.3v, not bad when fully charged is was 12.6v.
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Somewhat. I balance charge as well, but if there is a situation where the balancer cannot equalize the cells before the CC/CV threshold, one or more cells could go over the 4.2v limit. Of course, this only applies to non-balancing chargers.
I'm not sure how the Triton works internally, but most chargers apply a CC charge until the voltage hits 4.2v/cell, then switches to CV mode and the current dwindles down to a set value before it shuts off. Actually, to be accurate, most chargers are always doing a CC charge, but at the "CV" phase, they just monitor the voltage and make constant changes to the charge current. But that's just a technicality. As far as the LVC point goes, I take it case by case. I like to see 3.5-3.6v/cell open-circuit voltage once the load is removed for about 10-15 minutes. All batteries will exhibit some voltage "drift" back up once you remove the load. How much they drift back up depends on their design. Cells with higher resistances will drop voltage under load more, and will drift back up more, so I set the LVC for 3.2v/cell. If you have a cell with extremely low resistance, there is much less drift once the load is removed. So, to get a decent resting voltage, the LVC needs to be set higher to compensate. The same approximate mAh is used, it's just a matter of understanding how batteries work and tailoring care and maintenance accordingly. The only pack I have every puffed was a MA pack, but no surprise there. It was being used in a setup that it should easily have handled. Oh yeah, I did puff another higher quality pack, but that was because it was a 2p pack and one of the cell pairs came apart causing one cell to handle the entire load. |
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