What's the deal with Lithium batteries????

[Fondulac]

After getting back into the sport recently, I see everyone is running LiPo or Lithium batteries... I also saw that some servo's recommend not using them based on the current draw. I have always used NiMH. What are the real advantages of these Lith's? Longer life, cold weather, longer charge, cheaper, lighter?

[luv2flyguy]

The Lithium Ion batteries will hold their charge, they will not self discharge, they are also lighter than the old Nicads or the NiHm. However a 2 cell pack will be 7.4 volts so you must use a regulator to bring the voltage to the correct voltage for the servos and the reciever. I was like you after being out of the hobby for several years, when I got back in everything had changed, but I really like the new battery technology. Also you may want to look into the A123 batteries, same chemistry but no regulators are required, but they are also some other things you must know about them. There is a thread here just about the A123 batteries, hope this helps, I'm really not the best person to ask, just thought I would throw my 2 cents in.

[sweetpea]

For GS what you see is LION. Lighter and more Mah than NIMH or NICAD and increased voltage. They do not create a memory either. Cost is about the same or less than NIMH. Most servos will require a 6v or so regulator though.

A123 are like a hybrid of LION. I personally don't like them but lots of folks do. With these you get increased amps so if your servos draw power these won't drop off. You cannot measure Volts though to see where your power level is. They stay at a constant Volt until they drop off. You have to buy the switch from Fromeco that measures it or just rely on flying a few times and then recharging and seeing how many Mah you put back in the pack. Using these figures you guess how many flights you can have before a recharge. These packs are at 6v

For foamies Lipo is the rage. They are 7.4-11.1 v or more. Very light weight, lots of power making foamies fly incredible.


If you are new to the game than get a charger that will charge all of these types......my chargers only charge LION/LIPO as well making A123 a further investment I don't wish to make as LION/LIPO have been working just fine for me.

[pepatrick]

Batteries are personal preference. All batteries have pros and cons. As far as I can tell…A123s only have one con. You cannot check their voltage. Now..this is also a benefit to the battery as well. When you charge the battery it might peak to 7.2 volts, but will drop off before you get the plane off the ground to 6.6 volts and hold that for the duration of the charge. One flight or 8 flights, the battery will still read 6.6 volts, but once it is used up it drops off fast..ok..not fast..immediately. Now..the good news…since it is a constant 6.6 volts, you don’t need regulators on most servos, and you get reliable clean 6.6 volts even during high current draw maneuvers. These things will discharge at 30c and burst to near double that. The reality is..it is more current than our 30% to 60% planes will ever draw. So... how is that we keep an eye on these things so they don’t take sudden nose dive in power. Fromeco has a couple of devices that are fantastic for counting the number of mahs used. There is a high current Kodiac switch of or a little inline device called the Weasel. The Weasel and Kodiacs will keep track of mahs used very similar to a fuel guage. If you burn up 300 mahs per battery per flight the display will read 0.3. I have found that these mah counters are not 100% accurate, but they are close enough to add piece of mind. I have 2 x 4600 A123 packs in my 40% Yak. At the end of the day, my counter read 1.5 after 5 flights per battery. I ended up putting a little over 1600 back in…so it is close enough to make it safe…I think..
If you do not want to use the Mah counter…then you can charge your batteries after each flight for a few flights. Track how many mahs you put back in the battery during the charge. Do this several times and get an average of how many mahs each flight would normally take. If you use a 2300 pack..and you burn 350 per flight..then you could probably fly 5 times before a recharge…You obviously want to have a safety margin in there.


What else is great about A123s?

• They are not flammable.
• 0 to full charge in about 15 minutes
• Much higher current draw than we can throw at it
• Extremely stable chemistry (current flow and not flammable)
• Cheaper than typical Lithium chemistry batteries
• A 2300 pack A123 is equivalent to a 4300 pack Li-ion as far as number of useful flights
• You do not have to discharge if you are going to store them for a while
• They don’t really need to be balanced (even though its not a bad idea every once in a while)
• Will last longer than typical Li-Ion and Li-Po batteries (shelf life and number of charges) - DeWalt Power Tools claims upwards of 2000 charge cycles before they start losing their zip. Some of the powertools that use these require a lot more current than anything our hobby will throw at it.

Negatives about A123s…

• Not much…
• Cant test useful life with a volt meter
• A little heavier than typical A123 technology…but even this is marginal.
• A Duralite Li-Ion 4300 pack weighs over 7 ounces…but the time a regulator is added it is over 8 ounces. A 2300 A123 back (similar by usefull load) weighs just over 6 ounces and requires no regulator…

It is tough not to consider A123s when looking at going giants scale. I am using them on the receiver packs of all my planes now and ignitions too. Do yourself a favor and do more research on all the batteries. Batteries are typically the least expensive part of a giant scale plane and probably the most important. The more you know..the better off you will be.

[Fondulac]

Thanks for posting the info, but I still don't understand the real benefits...I will continue to research it though as it seems to be a technological advance and not just marketing. I also see guys running 6.0 volts for more servo torque and running 200+ oz servo's which seems a little overkill- (I know I'll get flack for that one! -probably not overkill in a 50%er but 5 ganged together on a rudder is) Maybe I have been away from it too long, running a std 4.8 volts with a 5oz 1500-2000maH NiMH pack and 70-100oz servo's used to work in 1/4 and 1/3 scale. Volt regs, switches, new stuff to buy, new chargers, can't check voltage....Thanks again for the info and bearing with me and my comments as I re-learn some of this stuff!

[pepatrick]

Look at it from this perspective. A123s are relatively cheap compared to other lithium chemistries. In a 40% plane 300 ounce servos are almost mandatory...and running Spektrum especially for high current applications requires 6 volts to the receiver. If a receiver does not get the proper voltage under load it will brown out. DSM Spektrum has a minimum voltage level of 3.5 volts before it reboot...I think Futaba FASST is 3.2 volts but regardless a freshly charged 4.8 volt battery can drop below this number if too much load is induced on it. If that happens your receiver can reboot and it could cause a disaster. DSM Spektrum has solved some of this by have a fast boot receiver that comes online almost immediately after a brown out...but..not something you want to have happen. Now keep this in mind...the JR leads (22 guage wire) that people plug into their receiver is capable of 4amp and a 7 amp burst...If you are flying heavy 3d then you can easily draw 7 amps so a single 22 guage lead will fail and good bye plane. You can either run multiple leads from the battery into the receiver and increase the max amp load the receiver can get, or use JR fail safe receivers with 16 guage leads that can handle 30 continuous amps and 50 amp burst. Your not likely to overload your electical system with these types of wires...Now..you can run all the 16 guage leads you want, but Lithium Ion batteries will not handle much more than 6 amp discharge without getting really hot...Li-Pos can handle it, but again..you have dangerous chemistry if the lipo mylar skin is punctured. A123 with 16 guage wire going into a either 16 guage on the receiver or multiple 22 guage leads going into the receiver will give you a bullet proof connection (almost)...

The best insurance is to eliminate the weak links in the system. 22 guage from battery to receiver is a very weak in the system. Nicad and Nimh and lithium Ion are all weak links as they simply cannot handle the demands of the the newer hi torque servos. This would include 8711s and the new Hitec 7950s that should be out soon. A123 and Li-Po can handle it...A123s are just a safer bet due to the more stable chemistry. It really is the perfect battery for our hobby.

[MikeC3D]

IMHO...for Giant Scale, Li-Po's are the way to go, we use Flight Power 2500mah x 2 for the Rx's, Jr servos dont need regulated, they handle 7.4v and have massive power and speed this way, 2 of us use Futaba 9156's and a Smartfly Turbo reg at 6.5v w/ batt share, (they balance equally during use). We can fly all day 8+ flights on 1 charge and still have plenty of voltage left, and check 'em whenever you want.... The bigger planes need these more powerful servos and they need the constant current to them, so the new battery technology is very much needed. But the smaller planes used for sunday circle ,loops dont really need it, I fly profiles occasionally w/o the fancy stuff and it works fine for the smaller less agressive flying planes.

[RTK]

I am currently migrating all my planes (except for electrics) to A123. No regulators needed, charge in 15 minutes, low combustibility. I use a cellpro charger that you can measure the mah put into the batteries. With every plane (after I cycle the batteries once) I go out and fly 3 or so flights. Charge the batteries and figure out how many amps I use per flight. Then you know when to stop flying and charge. I don't think you can find a better battery power system. KISS

[reyn3545]

You can add Fromeco Kodiak switches to your plane and see how much power is being used on each flight.

[pepatrick]

I guess if you get JR servos for free then they handle 7.4 volts. I wouldnt run any JR servo on 7.4 volts until the new HV servos are out. I know there are some guys doing it, but wouldnt trust it. Its also not covered under warranty if they get zapped. Even the HV will be able to take advantage of A123s due to higher than 6 volt rating. 7.4 volts on a 86 /8711 is asking for trouble.

Yeah...yeahh..I know..you have been doing it for a while and have not had a servo burned out. It doesnt mean it will not. Not really a recommendation I would make for someone getting back into the hobby.

	Quote: Originally Posted by MikeC3D
	IMHO...for Giant Scale, Li-Po's are the way to go, we use Flight Power 2500mah x 2 for the Rx's, Jr servos dont need regulated, they handle 7.4v and have massive power and speed this way, 2 of us use Futaba 9156's and a Smartfly Turbo reg at 6.5v w/ batt share, (they balance equally during use). We can fly all day 8+ flights on 1 charge and still have plenty of voltage left, and check 'em whenever you want.... The bigger planes need these more powerful servos and they need the constant current to them, so the new battery technology is very much needed. But the smaller planes used for sunday circle ,loops dont really need it, I fly profiles occasionally w/o the fancy stuff and it works fine for the smaller less agressive flying planes.

[pepatrick]

Seriously..if you are looking to get into giant scale...Take a look at these technologies...and do the research on them. It is as simple and solid as you can get.

Batteries: A123
Receivers JR R922 / R1222 or Spektrum AR9100 (powersafe receivers)
Servos: Futaba 9156, JR 8611a/8711 Hitec 5955/7955 7950.

I have always been a big powerbox and smart fly junkie. The technology has changed and these power distribution units are just another place for things to fail. Granted they have proven reliable in the past. The equipment above will give you as simple of a setup as possible and actually is less expensive to outfit a 50 / 100 /150+ cc plane.