I must say I am impressed with the new LiFe batteries I guess there the same as the A123's. I installed an 1100mah LiFe battery in an plane that has 6 servos put 50 minutes of flight time on it, It then sat in the garage for several weeks when got the plane out today the battery was at 6.62 volts loaded with 150ma.

Im sold on them, I just dont like to take it out to charge it. I guess I will have to by some balance connector extensions. Then I could do it in the plane.

The cheaper LiFe batteries are not exactly the same as A123. The A123 is a LiFe technology, but it uses some nano materials to improve the impedance and output. That's why the A123 brand costs more than most other LiFe batteries. They all share the qualities of lightweight, fast charging, and no self-discharge.

that doesnt tell you ANYTHING.............
these batteries DO NOT DECREASE VOLTAGE UNDER LOAD UNTIL ITS WAY TO LATE
ive seen LiFE batteries be 95% discharged and still hold their voltage under a load, now once its gets to around 98% discharged the voltage goes from 6.6 to well below 4v basically killing any power you had to your reciever

that being said these things hold their charge much much better than nimh/cd, id expect that battery to still have 50% battery life

thats a little scary I guess I will have to keep a close eye on it and start doing a discharge on it and actually see whats left.

Don't be distracted by all the negative hype. Proper care of any battery pack will give you what it has. We went through all sorts of issues with NiCd and NiMh packs but they work as advertised, as long as we use reasonable care and diligence in using the things.

Go ahead and fly with it, but, as any other technology, be aware that these, like any other battery pack, do not supply unlimited power... they have a life (pardon the pun) and will do just fine in your aircraft.

Use voltwatch and do as I always suggest... check it before and after each flight and you will be just fine.

CGr.

How does voltwatch work? Is it just a voltmeter that gives a reading? If so this is BAD info. Do not use Volts to determine whether a battery is suitable for flight. As the other poster said, these batteries hold voltage untill they are almost dead. You could check the volts and it seem fine but a couple dozen mah later the volts can drop rapidly. I use A123 and my gas and glow planes except for my 1/2a stuff. These batteries are safe to use and perform awsome, however I wouldn't trust a volt reading to determine when they need to be charged. Just figure out how much you are using each flight and figure out how many flight you can fly between charges.

Hi,
An electronic engineer at our field really likes these batteries for his big gassers. He uses them on the RX and ignition. He keeps track of the MaH on each recharge/discharge. This is the only way to tell how much flight time a pack has. As said before these packs have a very flat voltage curve. A volt meter MAY not be a safe measure depending on the power requirements of the given plane. Timing the recharge if you can't measure Mah. Keep a record.

thats the only downside to life batteries (its actually a big + if you use it to your advantage) is that you cant test them on a amp/volt meter
also voltwatches will not be as useful
the only way to see how much they used is to discharge/charge them

I actually got a 3200mAh one. I was intending to use it on an electric airplane also but dropped that idea.

Right now, the battery is fully charged, so much so that I can charge it with the Triton2 charger. It simply says "Batt V too high" I kept it connected in my air plane for 8hours and even after that it wont charge through the charger. How many of you have that problem? I have the Hobbico 2 cell packs rated at 3.3V each

Ameyam

You don't need to charge them with the balancer every time you charge the battery.
You can also solder a regular charging plug instead of the balancer plug. I have a new PC so don't have the links available. Someone please post a link if you know what I'm talking about.

just a heads up.

this is an example:

http://www.hangtimes.com/a123_packs.html

read this:

http://www.hangtimes.com/a123rxsetup.html

The Triton 2 can't charge LiFe batteries. The Triton EQ can.

Yes, Jester, I have the Triton2 EQ with balancer. It has a dedicated LiFe charging option. Researched and took them together

Ameyam

No, it's not just a voltmeter that gives a reading. It is a LOADED voltmeter that gives a reading. The load is the system load.. receiver and servos. I just wonder how many times I have to repeat this?

Before you make such a statement, I suggest you do a little research. There is lots of information available here on RCU on Voltwatch 2.



CGr.

As a test two weeks ago, I decided to determine my no fly voltage on an A123. I have a 30% Yak 54 using a single A123 2300 mah pack (2 cells). First I connected the battery to a digital volt meter with a 300 ma load (resistor). With the voltmeter connected to a computer, I looked for the sharp drop in voltage indicating the battery was fully discharged. I then put 200 ma back into the battery, and put it back into my plane. 200 ma is my typical discharge for a full flight.

I have the Aurora 9, so I get a readback from the reciever on the transmitter. The battery was reading 6.2 volts on the transmitter while cycling the control surfaces. I kept it on, and let it drain down. Once the voltage hit 6.1 volts, it started dropping, but not so quickly as to be undetected. Bottom line, as long as I am reading at least 6.2 volts on the transmitter, I'm still good to fly.

On my plane, these cells are typically good for about 10 flights before I recharge.

Brad

Sorry for raising this issue again, but how do you charge this battery? I recently bought the Hobbico version (3.3V nominal voltage x 2cells, 3.6V x 2 fully charged). I havent discharged it yet, just received it couple of weeks back. But when I put it on the Triton2 EQ balance charger, it says " Batt V too high". Is this a common problem caused by fully charged battries? I couldnt get the battery to discharge "a little"...its 3200mAh and it hasnt discharged even when I kept it connected to the RX for 8 hours (I just kept it connected, didnt keep moving the servos as I worry I will wear them out before the battery)

Ameyam

It appears from your description that this is a 2 cell LiPo battery. If so, you do require a certain type of charger to charge them, i.e. a current limited/constant voltage type. LiPo's, if improperly charged or accidentally shorted out, can erupt in flames that are very difficult to extinguish as you would need to blanket them in some substance to prohibit an oxygen source such as air. Sand will work.
In general, you must charge these at a not greater than 1C (3.2 amperes for your 3200 mah battery) and a fully charged cell will be 4.2 volts (8.4v for two cells in series). If you discharge them much below 3 volts per cell, they will be permanently damaged.

100%! Thats exactly what I do with these batteries. you need to establish the drop off point of the voltage.
For my Tx Battery it's 9.5V. After it moves to 9.4V i have 15min before it hits 8.5V at which point I am 2min away from the low voltage alarm on my Fut T6EX 2.4.
Same for the Rx Battery. the drop off voltage is6.2V thereafter I have 10min or just about one flight.

I plug a Lipo type Voltwatch into the Balance lead of the Life pack and have it mounted under a window on the airframe. This way I can see what the voltage is on the ground when I power up. I limit flying to min 6.4V thereafter I charge up. But the 6.6V battery gives me probably 12-15 flights! I don;t constantly fly on the controls, thats why planes have wings....

Yeah, what many don't understand (keeping in mind that this IS a beginners forum) is that the more you move the sticks, the more the servos work, and the more of a drain there is on the battery pack.

Often, pilots will try to correct for movement that they have no real control over, or with the latency involved, correct for something that has already happened, thus overcorrecting.

What I learned way back when, during my training, in fact, was my instructor told me to leave the sticks alone during a straight and level pass. I did and watched the plane. I realized that it moved the same way no matter what I did. So, I tend to leave my sticks alone, don't overcorrect, in other words, when I don't need to do anything but fly and watch.

You said it, TimBle

CGr

Yeah, what many don't understand (keeping in mind that this IS a beginners forum) is that the more you move the sticks, the more the servos work, and the more of a drain there is on the battery pack.

Often, pilots will try to correct for movement that they have no real control over, or with the latency involved, correct for something that has already happened, thus overcorrecting.

What I learned way back when, during my training, in fact, was my instructor told me to leave the sticks alone during a straight and level pass. I did and watched the plane. I realized that it moved the same way no matter what I did. So, I tend to leave my sticks alone, don't overcorrect, in other words, when I don't need to do anything but fly and watch.

You said it, TimBle

CGr

OK, CG, I understand. This was not a thread about Voltwatch. My point still stands: you should not base the safe usage of A123 or Life batteries by a volt reading, loaded or not.

Ok. You prefer guess-work because that's what your first post suggests. A reasonable approach would be not to fly the plane until the battery is just about to fail. That's asking for trouble. No matter what calculations you make in advance, you can never factor in servo usage under varying conditions.

I'll stick with my voltwatch. It works just fine, and I am very conservative when it comes to deciding when to fly or when not to fly.

CGr.

CG I have to concur with ndb. Voltmach is not going give you any useful info since the A123 discharge curve is so flat & drops so suddenly at the end. I've read this many times here and elsewhere on the web.

No disrespect, just a heads up.

I'm not sure why I'm getting an hostile vibe from you CG, we can disagree and keep it friendly in nature.

At any rate, I do not use guess work. I know how aproximately how many mah I use for each flight from experience. I know how many flights I will fly between charges. I use a battery that leave me a very conservative reserve. I discharge the batteries so I know how the general health of the battery is. So if I use approx 150mah a flight and fly 5 times between charges I use about 750 mah. This out of a 2300 mah battery. I hardly think that I am just guessing whether I'm safe to fly. While I agree these numbers fluctuate, not enough to remotely threaten the reserve.

Just curious, what loaded voltage reading do you find safe to fly?

You just said it. Experience. This is a beginners forum. Most pilots here fly with a lot of overcorrection which shortens battery life more than it would for you and I. The prediction method is fine for experience but probably not for beginners.

Yes, LiFe packs have a very flat discharge curve as compared to NiMh or NiCd packs. But, the voltwatch is simply a tool to monitor the voltage of teh battery pack under the on-board load. No more, no less. A prudent pilot will keep a close eye on the condition of their battery pack and not fly when there is any question about the charge remaining in that pack. Experience tells you that you can fly x number of flights for your pack and you fly that with that in mind.

The inexperienced pilot will fly, say 5 flights, because someone said he or she can fly 5 flights on a charge. Is that the right approach? Maybe... maybe not.

I'm not being negative here, I'm trying to be practical and trying to point out... probably not very well, that predictions work for experienced pilots. For beginners, there has to be a tool. Even your method will put you in a position of that "last few milliamps".

I fly my Skylark 70 with voltwatch and the LiFe packs. I watch it constantly... of course, when it's on the ground. As I've said before, I check it before and after each flight. When it begins to flicker down from the top green LED, I know that it's about ready to charge. Many here will push it to the point where they will try to get one more flight out...

Don't get me wrong, here. Your information is good stuff... mainly because it points out that the curve is very flat and has a very sharp knee. We've had all sorts of discussions about battery packs and how they should be used. Some advocate using LiPo packs with a regulator and I always say that it adds another point of failure and that beginners should keep it simple, meaning maybe they should consider using LiFe packs after they become more experienced. There is no really easy answer. All I can say is that your prediction method works for you, an experienced pilot, but may be slightly over the top for a beginner with everything else that they have to think about before, during, and after each flight.

CGr.