J-3

I fly 40 to 120 sized glow and 1/4 scale gas (33cc Homelite, & G20EI engines) airplanes, and I would like to know if a 2 cell A123 pack would be a good application as a receiver pack for the Glow models and maybe an ignition pack for my G20EI on my gas airplanes?

Any ideas and suggestions would be welcomed, especially "everydayflyer" who seems to be a really great asset here!

Thanks...Brian

everydayflyer

Use 2S 2300 packs and if you want more capacity use 2S2P for 4600 mAh capacity. No regulators , etc. required. 2S approx, same voltage as a 5 cell Ni. A123 capable of delivering high amps. and have a really flat discharge. Great fast charge capabilities. Many use a CellPro4 which will charge a 2S at 4A. so top off are fast.


Charles

J-3

Thanks for replying everydayflyer, I have read a lot and needed a little conformation. I will order the batteries and see what I can come up with for charging. Thanks again....Brian

everydayflyer

For those who want rather detailed imformation on A123s as receiver packs this site has a good run down on this application.

http://mysite.verizon.net/vze2qbfc/id25.html

Charles

TedMo

I have been attempting to learn as much as possible prior to committing to the A123 cells. Thus far it appears like this is the way to go for many good reasons. My only problem right now is that from what I have read there are more than 1 type of 123 cells. Or perhaps more correctly several types of Li ion cells? This is what has me stumped. I want to be sure I purchase the correct ones. I haven't seen them available as yet in any of our usual suppliers sites i/e Horizon, Tower, FMA etc. Perhaps I have been missing something? Also since I generally use 3S1P Li Po's which supply 11.1 V. will 3- A123 cell at 9.9v. provide me what I need to power my RX and servos properly? Will I need a BEC?

everydayflyer

The best LiFePo cells are true A123 Systems / A123 Racing cells also used in DeWalt 36 volt cordless power tools.

Places to purchase ready made packs

http://progressiverc.com/LiFePO4.html


If you are using a 3S LiPoly then you are using a regulator. You can use a 3S A123 with a regulator or a 2S without a regulator. Use Link in posy above .

Charles

dirtybird

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Capt Lou

J-3:

I agree with what Charles said. I just got a Wild Hare 50cc Extra. I power it with a DA 50cc gas engines and put a JR X9303 2.4gHz system in it. I use a 2300 mah A123 battery pack for the ignition and and dual 2300 mah packs (one is a back-up) for the receiver. I use a Cellpro 4s charger to charge. This is a great combination. I can easily get 3-4 flights out of the packs and they charge up in just 10 minutes at the field. They give you everything you want in batteries - good flying time and quick charging and the A123 does not have the heat/explosive issue of traditional lipo's. The Cellpro also allows you to check accurately the capacity of the battery at charge. I was uncertain about these batteries but a friend, who is an electronics techie, convinced me when I saw how well they worked in his 50cc plane. However, you need to be cautious about the voltage output as a battery pack is rated at 6.6v (3.3v per cell) and you need to determine how this impacts servos that are rated at maximum of 6.0v. Futaba has told me that they can be used with its R617 receiver because it has an internal voltage regulator but recommends that you use an external voltage regulator for the 6.0v servos. My technie friend tells me that you don't need the regulator on the JR system.

roydefiant

capt lou, are you using a voltage regulator on your ignition pack for the da 50? tech at fromeco tells me the answer to that question is unknown and recommended using one for now

Capt Lou

roydefiant:

I'm not using a voltage regulator on my DA 50 ignition. The DA instruction manual discusses only a 4.8v and 6.0v battery pack. As a result, I sent an email to Desert Aircraft and asked if the A123 2300 mah pack (6.6v) was ok to use with their ignition without a voltage regulator. Jeff at DA responded that it was ok to use the A123 batteries without a regulator.

rmh

The modeling public at large knows almost nothing about the 123cells and the advantages over just about any other cell chemistry.
This will soon change.
The problem has been that the cells were simply not readily available for high markup sales outlets.
Guys who are "do it yourselfers" have found sources and many have switched exclusively to them.
Some points to consider:
The chemistry is safe -won't explode if overcharged -but will burnup if direct shorted .
The power output is quite constant -that is , over a full charge - the output voltage is very constant and amperage demands don't change this noticably.
Life of cell is very long - 1000 to 2000 cycles
shelf discharge is almost zero- charge now - fly months later - pack still ready to go.
RC compatible a 2 cell output is a nominal 6.3 volts which is like a almost fully charged 5 cell NiCad pack- most equipment works with no regulators .
cost effectiveIF purchased and self assembled to needed packs
Look for ready to use packs to hit the market -
Purchase a charger which reads out (displays) cell state of charg -
Tho the balancing is pretty much automatic - you ought to know how these cells actually charge/discharge and self balance.
Used as power for electric model other attractive features become apparant -

TedMo

Charles: you replied to my post on 5/10 by stating that if I presently use 3S/1P Li Po's I am using a regulator. If you mean the Bec that's in the ESC that's correct. Will that also work with the A123 cells since they supply a different voltage than the Li Po's? I also at times use 4S/1P Li Po's for some applications. I guess my main question is will I have to change anything to switch to the A123's? By the way I presently use the FMA 4S charger which has a 123 mode so I believe that is good.

everydayflyer

Well this thread is / was about using A123 as receiver / servo and ignition packs for gas powered models.

If you are using LiPolys with a ESC and built in BEC to power an electric motor then yes they will work. Voltage is lower than LiPo and in general you would add a cell. 4S A123 to replace a 3S LiPo ,5S A123 to replace a 4S LiPo. Most ESC based BECs are maxed out on 3S LiPoly. It is therefor best to use a separate BEC. Switching ones are much better than the linear ones built into most smaller ESCs.


Charles

TedMo

Thank you Charles for your reply. Sorry I didn't realize I had chosen the wrong thread. At any rate I now feel confident enough to order some A 123's.

Capt Lou

Dick:

You are right on point with your remarks. For your information, I purchased ready made 2300 mah A123 battery packs for my JR R921 receiver/flight pack from www.sincityjets.com and also use them for my igition on a DA 50cc gas engine. The battery packs came fully assembled with JR connectors. I also purchased from Sincity Jets a Cellpro 4s charger witha JR adapter connector. I went flying yesterday and after 3 flights the batteries registered at 85% capacity when I began to re-charge them which took about 10 minutes to do.