Charging Lipos

[barsalb]

How long should it take to charge a 1300Mah 25c 3s Lipo? I flew it until the cutoff shut it down. It has been on the charger for 90min. and it says it's charging at 0.1 amps. Been there for awhile. Triton 2 EQ. Thanks for help.

[Sir Crash-A-Lot]

If the cells were not balance it could take a while. At .1 amps it is not going to go very fast so I would check to see if the cells are at 4.2 volts and take it off charge if they are. But if a cell is still out of balance keep an eye on it and let it charge.

Mike

[xmech2k]

Is it charging constantly at .1 amp, or did it start higher and go down to this? What's your LVC set to? I fly my batts usually down to around 3.4v/cell roughly, then it usually takes around 30 minutes to put a storage charge on, then later, another 30 minutes or more to get to full charge.

[barsalb]

thanks

[matiac]

How long can a LiPo be stored with a "storage charge" anyway? I've got the stock 25C 14.8V 2600mah just sitting here waiting on the charger to arrive. I did use the battery to get the landing gear down, and check stuff, other than that nothing else. It came with the RTF Airfield (Nitroplanes) P47D I'm DTF (Dying To Fly). In other words, should I even be using it for checks and balances, or wait for the charger to arrive?

[mred]

Originally Posted by matiac

How long can a LiPo be stored with a "storage charge" anyway? I've got the stock 25C 14.8V 2600mah just sitting here waiting on the charger to arrive. I did use the battery to get the landing gear down, and check stuff, other than that nothing else. It came with the RTF Airfield (Nitroplanes) P47D I'm DTF (Dying To Fly). In other words, should I even be using it for checks and balances, or wait for the charger to arrive?

The storage change is intended for long term storage. It won't really hurt the battery to use it a little as long as it is a little and not draining the battery down below about 3.4 volts per cell. Never take one below 3 volts per cell or you may damage the battery. Charge the battery at 1C when you get the charger and that should be 2.6 amps for this battery. It will taper off after it gets almost a full charge and the last little bit will take awhile. It normally takes an hour or more to charge one that is fully discharged, but watch it and make sure it does not over charge and make sure you have it set to LiPo before you start. You should see 4.2 volts per cell at full charge and anything over 3 volts when discharged. I like to time my flights to use 70% or less out of the battery when flying. That will be 1820ma or less when you charge it back up again. You can use the full 2600ma if you want to, but it will cut down a little on the life of the battery. One thing I like to do is cycle my battery before I fly a new one. I charge it all the way and then discharge it on the charger at 1C and then charge it again. I do this three times and while I have never proven it helps, I have heard from several places that this helps condition the battery and makes it last longer.

Ed

[startazz]

Originally Posted by matiac

How long can a LiPo be stored with a "storage charge" anyway? I've got the stock 25C 14.8V 2600mah just sitting here waiting on the charger to arrive. I did use the battery to get the landing gear down, and check stuff, other than that nothing else. It came with the RTF Airfield (Nitroplanes) P47D I'm DTF (Dying To Fly). In other words, should I even be using it for checks and balances, or wait for the charger to arrive?

I've got a P-47 and it's a great looking and flying plane but mine isn't the NP's one,but still the P-47 is a great plane so you have good tastes.

Not sure how long they can be in storage mode but i have to leave mine in storage through out the winter months and mine have all been fine,i've read they can be left in storage mode for years but they won't have a long life after you start to use them,don't quote me on that as i did say i read that online some where.
You say you have used your battery just to do a few checks and to get the LG down,well that should be fine but i wouldn't do it again or to many times as you might over discharge it and then it wouldn't be up to much at all.

I use the Nano-Tech and the blue Turnigy batteries from Hobbyking.com which are a couple of really good batteries,the Nanos come in some good high C ratings too and i tend to use the higher C ones in my EDF's (Electric Ducted Fan) jets and the 20/25c in my warbirds.

No matter where you get your batts from you might find it better to get two or three for each plane,well thats what i do so i don't have wait for the battery to charge before my next flight.

http://www.hobbyking.com/hobbyking/s...arehouse_.html

[matiac]

I have heard about "cycling" the battery before use, and will probably do that with any new ones I get, just to be on the safe side. Do these LiPos get "memory" like standard batteries do? I know with the Airhog helis, if you run the battery to half, and charge it from there all the time, it'll loose half it's use, so I would always run it completely, let it sit for 10 minutes, and charge it again. Yeah, I saw some pretty scary stuff about LiPo batteries online, and the local guru at the Hobby Dispensary told me some stuff to do while charging, so I'll be "by-the-book" where that's concerned.
And yeah, I was looking at several different planes, and it came down to either the big Corsair from Banana Hobby, or this BEAUTIFUL P47D from Nitroplanes, and the Thunderbolt being one of my favorites, well, it was a no-brainer, besides the fact it just looks easier to fly than the others...it's my "goal" plane after these Helicopters and flight sim time...a LOT of flight sim time...

[flydiver]

You cycle your lipos to LVC and they'll have a short life. You cycle them lower and you'll have no life-that's called over discharge.
There is NO MEMORY for lipos....unless you count that they 'remember' abuse and are unforgiving that way.

FWIW memory for NiMh is pretty much a male myth. Sure, they die from abuse also. Luckily they generally don't start a fire for doing so. Since hoards of people (the majority probably) don't have a clue how to manage NiXX properly they ruin them and blame it on memory.
Dan's Quick Guide to Memory Effect, You Idiots

[mred]

Well now, I have been cycling my LiPos since I started using them and still have my oldest battery and it is still in use and responding great. It's up to about 300 cycles now and still going. I use a slow discharge on the cycle and a normal 1C on change and so far everyone of my batteries are working great.

Memory had to do with NiCad batteries and yes they do form a memory, but that memory can also be broken just by cycling it a couple of times.

If you stop flying at about 70% usage, then the batteries should last you longer then going to a full discharge. For a 2200MAh battery, you should not have to put more then 1540 back in. I have gone to 1700 a couple of times and it doesn't seem to have hurt the battery much, but I have never used the full 2200 out of the battery. You can use this formula to get close on the flying time of any battery. Capacity in AH / amp draw x 60 = minuets of flight time. You use full throttle amp draw in this formula and then adjust your flight time according to how you use the throttle. You should get close after a couple or three flights using a timer. You should also adjust it for 70% usage, not the total capacity of the battery.

The biggest problem people have with short life out of LiPo's is not using a storage change if you are not going to fly for awhile. After a weekend of flying, don't charge them all the way up, just put a storage charge on them. Then when you get ready to fly again, charge them all the way up and have fun. I put a storage charge on mine if they are going to sit for more then about 3 days. Just me, but it has worked so far.

While you are getting all that flight time, why don't you get a nice easy to fly foam park flyer to practice on. Real world is different then flight sims.

Ed

[JetPlaneFlyer]

Cycling wont harm Lipos but it doent do them any good either. They are good for a certain number of cycles (depending on many variables) deliberate cycling on the bench simply uses up some of thos cycles. I'd rather cycle them by going flying

[50+AirYears]

Been flying electrics something over 20 years. Never saw "Memory" with Nicads, MiMh, or LiPos. Only problem I ever had charging a NiCad or NiMh that someone called "Memory" turned out to be a failed component in a smart charger that let it shut off too early, apparently reading an incorrect delta-V, and indicating complete charge, at ambient temperatures over about 85 F. And I did have a couple NiCads turn into incendiaries on early simple timed chargers. I always let my batteries cool down till they feel like they are around the ambient temperature before recharging. I've even used water to cool them down when I was low on the proper sized battery packs for the plane I was flying. And I usually fly until I notice a decrease in performance, especially needing to go near full throttle to stay airborne. Holdover from glow days, I guess.
All secondary battery chemisties have a finite life, usually designated in terms of charge cycles, which pretty much means discharging the battery to the specedlow
voltage level and recharging to full charge.
Since using LiPos, I've never had a fire, but I have had them seem to suddenly go flat, even when just off charge, and just a week ago, I landed, and found a 2S 900 Mah pack very hot and swollen. It went into a convenient water puddle for an hour, then I cut off the connector and and spliced it onto a new pack.
There's a lot on various threads about batteries, some of which actually agrees with what the manufacturers' technical publications say.

[kyleservicetech]

Originally Posted by 50+AirYears

Been flying electrics something over 20 years. Never saw "Memory" with Nicads, MiMh, or LiPos.

Yeah, I've been fooling with Nicads for some 45 years, and did run across that so called "Memory" effect at work. We were selling some 600 24 volt Nicad battery packs in our controls for backup power, and I went through a LOT of them in answering customer complaints over the many years.

Now, as for that so called memory effect, most of that memory effect was a voltage sag during a battery discharge test. That voltage sag could be on the order of 0.1 or 0.2 volts more than a battery without the memory effect. Cycling the battery would eliminate this voltage sag effect.

And, during those many years, I only ran across that "Voltage Sag" condition a dozen times or so.

By far, the most common Nicad cell failure mode was a shorted cell. You could "Bust" those shorted cells loose with a very high charging current for a few seconds. But in our application, if the battery failed, secondary damage could be in the many thousands of dollars. Simply was not worth it.

[50+AirYears]

When I got to Wheelus AFB in 1965, we were trying out NiCads for our 24 V equipment. Lots of problems with hot weather then. I think it was good they didn't make it into planes. Basically, we'd get a lot of single cell drop-out. Of cours, since each battery had something like 20 1.2 V replaceable cells, we got to play around a little at the MA club on base. Found out that with a quick short across the cell terminals with a 5 Ohm 15 or 20 Watt resistor, then s slow charge overnight, we had great glow plud batteries.
Had tech papers from a couple NiCad manufacturers talking about the "Memory" effect. They could not re-creat a "Memory" effect with computer countrolled cycling of thousands of cells and batteries, to duplicate what was supposed to cause the effect. What they did find was the formation of crystalline Dendrites between plates that reduced the capacity. High Voltage spikes could burn out the Dendrites, restoring MOST capacity, but with reduced life and capacity.
In a similar vein, at the lab I retired from, we used to recover dead Gates gell cell batteries by charging the 2.2 Volt cells at about 24 Volts until the current meter started rising. Then we'd quickly drop the charging Voltage to 2.4-2.5 V and leave for 3 oe 4 hours. Cells would be useable for a year or more. But, one day while doing this, I got asked a qquestion by my boss, obviously distracting me. I caught the needle rise probably 5 seconds after it started. Ever have a Cherry Bomb go off right next to your ear? We found pieces of lead plate 20 feet away. Luckily, no other damage or injury. We never again attempted to reclaim those cells again.

[matiac]

Got another question. Now, when I received the plane, and got it put together, plugged it up to spool the prop, check servos several times, I finally got around to checking the battery's overall voltage with my multimeter, and it showed 15.68 volts for a 14.8 volt battery??? Is my meter off, or is this battery almost 1 volt over it's capacity, and is this acceptable? I checked the battery at the 20VDC setting on the meter, it's a digital meter from Rat Shack. Have several other batteries I checked to make sure it's not off, and they're all within their parameters, so why would this one battery be over it's rated voltage after several uses?

[xmech2k]

Lipo voltage varies quite a bit depending on charge state. a 14.8v battery is a 4 cell, average 3.7v per cell. Fully charged is I believe 4.2 volts/cell, so that comes out to 16.8 volts when fully charged. So make sure you charge that before you fly!

And just wondering, these questions are making me wonder if you're not in over your head with that P-47? I'd hate to hear you crashed it first time out. And read up in the forums about that big Corsair if it's the one with the folding wings. Looks great, but it's a disaster unless you're ready for some serious headaches.

[matiac]

The only thing over my head are these LiPo batteries, I've never dealt with them before, and reading all the horror stories has me a bit concerned about doing anything could risk a fire. I have flown R.C. planes in the past, albeit the distant past, and while the plane I flew wasn't quite so big as this one, I never had anything serious happen to that one. And, I have been using an FMS sim at least an hour every day, taking off and flying around aren't a problem, nor is orientation, that all came back to me, but for some reason, landing is a sore spot, and I'm not even thinking about flying the real one 'til I can do everything on the sim without thinking, I'm there now with take-off and flight, just gotta work on them landings, gonna try out that Clearview sim tomorrow, because although Dynam tells you it's a 6 channel sim, can't retract landing gear, although I hit the button anyway...the CONTROLLER is 6 channel, not the software...

[mred]

A cars 12 volt battery will read about 13.8 if it is fully changed, but put under load it will drop to around it working voltage of 12 volts, depending on the load of course. The same is true of any battery, they all read higher right off the charger and no load on them. Put that LiPo under load and it will read around 14.8 volts. At 4.2 volts after a charge, a reading of 15.68 just means that it sat for awhile after charge, or your charger is not charging it all the way. Some chargers do this simply because of the rotten calibration they get a the factory. This voltage is nothing to worry about.

What you worry about it charging them OVER 4.2 volts per cell. That is when you start getting into the fire and flaming area. How much over that voltage you can go, I don't know, but every battery I charge is watched by me until it finishes and I never leave the room while I am charging them. The only fire I have ever had was from charging a NiCad and that was my fault. The wires started burning due to a short and that was my fault. Never did that again.

Ed

[matiac]

Haven't put it on a charger yet, I got my charger, but it had every kind of charger plug except the one I need, so that's on it's way. It's still got the factory charge in it, and initially, I didn't think it even HAD a charge (didn't know about "storage charges" or 3.7 volt minimums at the time), and upon discovering it did, put the gear down, checked control surfaces...several times, and still get the 15.68 reading, unless like a car battery, they come back up to voltage from sitting. I'm only asking all these questions about LiPo batteries because this is my first exposure to them, and the initial things I read were less than favorable in that they are considerably more dangerous than most rechargables. Flub-ups can be costly.

[xmech2k]

OK about your flying level, Matiac. Just checking, it happens a lot!

As far as the batteries, I'd recommend going through this thread;

http://www.wattflyer.com/forums/showthread.php?t=31071

Search for the battery stuff. Like Mred says, lipos aren't THAT dangerous, but you just have to take care of them. Don't overcharge them, don't short the terminals, don't abuse them, they'll be all right. I have seen a couple of really bad crashes where the lipo lit up, but it's rare.

[MX5Seeker]

If treated right, I think LiPos are safer than going around with a gallon of 30 or 40% nitro fuel.

[mred]

One of the problems when they first came out was that no one really knew anything about them or how to maintain them. A couple people lost their house from fire and there were a few cars burned up do to bad or no information and abuse. Charging with the wrong charger and several other problems came up. Now things have pretty much settled down and most people know what they are doing and try to get the new people headed in the right direction. Most of those horror stories are gone now and the ones that remain if really looked into was because someone did something very wrong.

One things you really need to do is LEARN how to handle them and use them. Don't guess. They are not NiCads and can't be treated like them. They will not take that kind of abuse. If proper precautions are taken, they are safe to use. At least as safe as a lot of other things in this hobby that are not really safe if handled wrong. Even at that, NiCads can be dangerous if abused to much. Learn what you are using just like anything else and you will get along fine.

Ed

[50+AirYears]

As far as the proper care and feeding of a LiPo, or any other battery, seems that nowadays, most manufacturers provide a pretty detailed instruction sheet with them. Read and take as Gospel.
I got my first Lipo about 8 months before I got my first LiPo compatible charger, a Triton EQ, with balancing connection. Didn't use the LiPo till I got that charger. Been using it for about 4 or 5 years now, and not just for LiPo..

[mred]

Well, you may get data sheets with orders for batteries here is the states, but I have yet to get one from HK. I am cheap, so I just use Zippy batteries and have had good luck with them, but all you get is a battery and nothing with it. If you order Thunder Power you will probably get full instructions with each battery with care and handling. Just don't count on that if you order from China.

They aren't really all that hard to take care of and use properly, you just have to learn. If you want to read about what happens if you DON"T use them properly, try this; http://www.wattflyer.com/forums/showthread.php?t=1584
If you read it carefully, you will see that the biggest mistake that causes fires is charging a 2 cell battery as a 3 cell battery. NEVER try this unless you want to start a fire. The number one proven way to start a fire is ABUSE and that is all kinds of abuse. Punching holes in them, bad crashes, shorting, over charging and such. They also are not chew toys for your dog. If you check around, there are not that many people that have had problems with LiPos. It's just that the ones that did get around and things get blown out of proportion by all the story telling.

I have used them for 5 years and never had a problem with them and so have the rest of the people in my club. Not one LiPo fire among any of us, so they are as safe as anything else if treated with respect just like anything else we use in every day life.

Ed

[50+AirYears]

I have LiPos from 4 or 5 differrent company names, bought either at LHS or Tower, and each came with an instruction sheet. Haven't tried anything from HK yet.
Only near combustion events I ever had with batteruies in 64 years of flying models, one was a NiCad where a mechanical timer stuck, let it overcharge till it started scorching a piece of wood it was sitting on. The only other "Incident" I ever had with a battery was with a Gates D size Gell Cell (Gelled Lead-Acid). When a cell would go dead, we'd recover them by charging the 2.2 V cell on a lab power supply, until the charging current meter started rising, at which you had about 6 or 7 seconds to reduce the Voltage to around 2.4. Doing one, I got distracted by my boss, was a bit slow getting to the Voltage knob. The cell blew like a firecracker, scattering bits of metal over about a 10 foot radius. Nobody was hurt, and we never tried to save money by recovering these batteries again.
Never turn your back on a charging battery. Never abuse any kind.