Scratchie

TheWoodCrafter

My Feedback: (1)

The battery with the lowest weight and highest power would be a LiPo.
NiCad and NiMH are old technology today.
They are heavy for the power they provide and they loose charge just sitting.

A123 is a brand of Li-Fe.
Newer chemistry than NiCad but still not as good as LiPo.
LiPo will not loose charge sitting.
LiPos need to be cared for properly or they can become dangerous and they require a LiPo charger.

Many use a 2 cell LiPo for a flight pack and put a regulator inline to step down the voltage to about 6V.

Most all modern RX can take 6V but some servos can't.

Goldenduff

I would agree with the above but.....

A123 can put out a higher ampage for similar sized (mah) packs, can be charged way faster and you can use almost their entire capacity so not sure lipos can be called the best?

I recently read an interesting article regarding battery pack weight. If a 2cell lipo pack is say 100g lighter than a NiMh pack that would be 2.5% on a 5kg bird. Much bigger savings can be made during the build post. However I digress.

To answer your question I agree with the above post- lipos but you will need an appropriate charger.

All the best

Jezmo

I would like to add to the previous post where the poster says "still not as good as LiPo". Weight wise that may be true but safety wise they are far far far superior. They, like LiPo, also DO NOT self discharge as NiCd and MiMH do. Being built in a hard type can such as NiCd's and NiMH's they are resistant to catching fire when in a crash etc. They also can be charged much faster (full charge from flat in 10 mins or less) than ANY other battery chemistry and the discharge rate is higher than most all other chemistry's. They are rated at 60 amps discharge for the 2300mAh cells and burst to 120 amps. Be aware that there are cheap knockoffs available from China that are not as good but still may have a place in our models. A single 2S1P A123 pack can easily power a 40%er although most people use 2 packs for redundancy.

pilotpete2

+1 on the A123 packs for receiver power. For the typical .60 size model an 1100mAh A123 pack is perfect, physically smaller and lighter than a 5 cell Nimh[8D]
Pete

Scratchie

Scratchie

It seems the A123 is the way to go - you guys saved me a bunch of time trying to figure this out - thanks.

Whenever I see Li, I think of fires from charging the batteries. Anything I should know before I start shopping? What is a quality brand of charger? What should Iavoid?<o></o>

bob_nj

My Feedback: (62)

There is no difference to answer your question.
It's just another way of saying two cells in series...

Rodney

For those just getting into RC, there is nothing wrong with the old dependable NiMh and NiCad batteries. In many ways they are superior to either LiFe or LiPo as they are more durable, can withstand miss use (often done out of ignorance with a new technology) such as deep discharge and improper charging techniques. You will find that using Eneloops (a NiMh battery made by Sanyo) for your transmitter is especially a good choice as you can charge it with the wall warts that usually come with most RC transmitter/receiver/servo packages, quite rugged, long lasting, nearly as good as LiPo in regard to self discharge plus other advantages. NiMh are also much easier for a NewB to handle in the plane as you do not have to remove the battery from the plane to charge them and you can use just about any charger for them. If you are really interested in battery care and performance, the following sites will give you some good info.

Battery information
http://www.hangtimes.com/redsbatteryclinic.html
http://www.camlight.com/techinfo/techtips.html
http://www.whenshtf.com/showthread.php?t=2153
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://users.frii.com/dlc/battery.htm

BarracudaHockey

My Feedback: (11)

For simplicity and reliablility, Rodney is dead on, hard to beat a nicad pack.

aghost

My Feedback: (13)

I think Rodney is right about Nicads for newbies. But with more experience, I went to LiFe batteries for the RX in six planes this past flying season (.60 size to gs warbirds). The LiFe batteries really did simplify battery maintenance, charging, etc. The conversion did require some reading to understand how to treat these batteries. Hangtime Hobbies has a good writeup on them. I bought my batteries from Hangtime configured so I could charge and balance a battery through a chargeport, rather than having to take the batteries out of the plane.

PropsnWings

My Feedback: (9)

Yep, I still to this day , trust my old trusty NiCd packs. I still have a NiMh pack or two as well. I like to keep it simple and not complicate things too much. I would suggest sticking with either a NiCd or NiMh.

Scratchie

Thanks, I'm into building, and i'm really just lazy flyer who used an old 4.8V system. However, since my next build will be a giant scale, Ineed to step up the electronics and servos so that all my work doesn't end up as kindeling.

BarracudaHockey

My Feedback: (11)

Well if you're getting into the big stuff then A123's really are the way to go.

That said, we were flying big planes long before LiPo and A123's were around

blikseme300

My Feedback: (118)

+1

GerKonig

Yes, also true people used to drive Ford T's and put pins up before turning on a transmitter... Life/123 is the way to go. There are cheap dedicated chargers for them, look at Tower's site (or many others)



Gerry

Flyfast1

My Feedback: (1)

Is it correct that LiFe packs can be safely charged in planes and don't have to be removed? Can LiFe packs handle high temperatures, e.g., staying inside a plane in the summer sun? I fly large warbirds and am considering using LiFe packs for a new project. I traditionally use NiCd and NiMh and have found them to be very robust and dependable.

Thanks,

-Ed B.

BarracudaHockey

My Feedback: (11)

@ Gerry....har har I work on technology for a living

Ed, yes they can be safely charged inside your plane and yes, I have sets with atleast 2 summers in the Florida sun flying nearly every weekend.

Take a look at WrongwayRC.com they have packs, chargers, diode drop downs so you can run your ignition on them, and will build the packs with genuine A123 cells with whatever wiring you want. I use them with 2 JR connectors and a lengthened balance tap.

I'm currently building the H9 giant Pawnee for review and thats what its getting, Dual A123 packs from WrongWay with EC3's feeding a 12 channel power safe rx.

DustBen

My Feedback: (3)

The end of charge voltage for a LiFe is slightly lower than a LiPo keeping it within specifications Airtronics describes.
LiFe cells should be charged to 3.6 volts/cell (7.2 total)
LiPo cell voltage is terminated at 4.2 (8.4 total).

I have read that LiFe batteries retain their charge longer than any of the others (LiPo, NiCd, NiMh).
In my experience, I found this to be true.

The one drawback about LiFe batteries is that their discharge voltage graph is almost flat. As they are used, the voltage barely decreases. Checking to see remaining battery capacity by directly checking voltage of a LiFe is valueless. The value you read in volts doesn't indicate charge state as a Nixx or LiPo does.

I use both LiFe and LiPo batteries in transmitters, but will not use a LiFe in an airplane. I'd rather use something like a NiCd and know the relative charge state than a LiFe... with an unknown charge state.

sirrom

My Feedback: (4)

I have to give a big +1 to a123 (LiFe) batteries. I have pretty much switched my entire fleet over to them. Especially my turbines. Example. My son has a big stick 60 which had a 2700 mah nicad in it. We could easily get 5-7 11 minute flights on that pack before recharging. I switched his plane over to a 2300 a123 2s pack and he can now do 15 11 minute flights between charges. On a busy weekend of flying we were neglectful and before we caught it he had done 19 flights over two days on one charge. When I did recharge it, it only took me 20 minutes to full charge and that included balancing. My RAM500 could only get two reliable starts, flight, and cooldown on one charge with a 1900mah high discharge nicad pack. Now I can do 6 reliable starts, flights, and cool downs on one charge with an a123.

As far as nicads and nimhs being simpler my a123's charge much easier with my cell pro. I set it to the a123 setting plug in the battery's balance/charge plug and let it go. I charge in my plane, it does not a regulator and have never had one lose a charge on me yet. I have Nicads, Nimhs, Lipo, LIon, and LiFe. LiFe is my favorite and probably will be that way for awhile. If the newbie were to do some light reading about the different battery chemistries, what's needed to charge, and how to charge they will be quite successful.

Dustben,
You actually can tell as the cell voltage drops. you can mearsure the cell voltage with the following.. http://electrodynam.com/rc/EDR-207/index.shtml I own one and it does the job quite nicely.


Patrick.

DustBen

My Feedback: (3)

Thanks!
I figured a precise voltmeter with a large enough load would work but I wasn't sure what the parameters of such a device would be.

It's on my "gotsta get" list.

Now... who makes small A123's? Something like 600-700 mAh 2 cells?

Flyfast1

My Feedback: (1)

Thank you Andy and others. This has been very helpful as I plan for the transition from NiCd and NiMh that has served me well for many years to LiFe.

-Ed B.

Whistling Death

The Eneloop NiMH batteries will hold 80% of their charge for up to a year and can becycled up to 1500 times.
I like these because have a small work shop and I keep some of my planes in my 14' trailer year round.
A123 batteries can be damaged in temperatures below freezing. NiMH doesn't care.

Jezmo

Blake, I am not trying to throw you in the grease here. I am not sure where you heard or read that about the A123 cells and freezing but the official word from A123 is they are good from -30C to +70C. I've left mine outside in the trailer when the temps are well below freezing with no damage at all. I have six packs total and all still work as good as the day they were new. Some of the packs are on the high side of 500 cycles now. I do try to keep mine below 140degs F though.