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Old Feb 20, 2012, 02:33 PM
Southern Pride
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Haralson County GA. USA
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Honestly I do not know either as charger manufactures / vendors do not list such specifications.

My early model iChargers did not provide very accurate IR reading IMO and while the 3010 and 306 seem to be much better they still do not provide the accuracy of any of my FMA Cell Pro or Power Lab chargers so I use the FMA chargers for IR readings these days.

I use to use my CBA and do a 1A then a 10A discharge and use Ohm;s Law to calculated IR.

I pulled a 5S A123 2300 at random from one of my battery boxs. Cell were at 3.300-3.305V and I started a 1A charge on one of my Power Lab 8s.

IRs @ 72F 11.6 / 12.9 / 11.6 /11.3 / 11.3 -----50% state of charge cells at 3.351V.

Charles
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Old Feb 20, 2012, 04:53 PM
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Thanks again, helpful info
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Old Feb 21, 2012, 04:18 PM
Epoxy & CA Investor
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can someone recommend a good place to pick up a LIFE pack to use unregulated into an AR8000 RX with 5 HS 985mg servos? This is going in a 71 Slick.
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Old Feb 21, 2012, 05:37 PM
Southern Pride
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Haralson County GA. USA
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Check with your favorite vendor perhaps or do a Goggle.

epbuddy.com is one,
http://epbuddy.com/index.php?main_pa...ou1un1fo2o8he7


aircraftworls is another, hangtimerc is one even Hobby King.,.

I would stick with A123 LiFePO4 cyclinder cells myself as I have never been very impresed with the prismatic cells however many say they are fine for receiver batteries.

Charles
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Old Feb 21, 2012, 05:59 PM
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those are nice, but then i assume you have to make an adapter to go from the deans into the RX?
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Old Feb 21, 2012, 06:03 PM
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never mind. I see one that is an RX pack that has the proper connections.
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Old Feb 22, 2012, 08:50 AM
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Just checking to see if the A123 cells are available in smaller sizes... say, 600-700 mAh.
I'm convinced of the concept of using separate battery power instead of routing thru a regulator/BEC and currently using LiFeP04 technology 700 mAh but would feel even better using A123's.
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Old Feb 22, 2012, 09:39 AM
Southern Pride
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Some lower capacity prismatic cell ones are available.

http://www.hobbyking.com/hobbyking/s...ever_Pack.html
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Old Feb 22, 2012, 02:40 PM
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Quote:
Originally Posted by everydayflyer View Post
Some lower capacity prismatic cell ones are available.

http://www.hobbyking.com/hobbyking/s...ever_Pack.html
Right.
I have that exact battery (4 of them) along with 2 of the 1100 mAh versions.
Still waiting for the A123's to evolve and become available in small capacities.
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Old Mar 23, 2012, 03:41 AM
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Quote:
Originally Posted by everydayflyer View Post
Honestly I do not know either as charger manufactures / vendors do not list such specifications.

My early model iChargers did not provide very accurate IR reading IMO and while the 3010 and 306 seem to be much better they still do not provide the accuracy of any of my FMA Cell Pro or Power Lab chargers so I use the FMA chargers for IR readings these days.

I use to use my CBA and do a 1A then a 10A discharge and use Ohm;s Law to calculated IR.

I pulled a 5S A123 2300 at random from one of my battery boxs. Cell were at 3.300-3.305V and I started a 1A charge on one of my Power Lab 8s.

IRs @ 72F 11.6 / 12.9 / 11.6 /11.3 / 11.3 -----50% state of charge cells at 3.351V.

Charles
Somewhat different to my readings, but then my SOC was at just below storage level, and cells were nearer to cool than 72F. I have had all 12 cells at storage SOC, and connected in parallel to ensure an equal voltage. They were left like this for around a week. Yesterday I separated all cells and checked the IR on each one twice, on each charger 106B and 1010B
( 4 times in all ) in quick succession. The readings for every cell were different each time. I averaged the results of all four readings into one figure.
I then did 1 X cycle of a discharge at 4.6A to 2.5V then a full charge, also at 4.6A to 3.6V to ascertain capacities.
Below is the result of all 12 cells, with data ordered as follows.
Cell No. IR: m/a to discharge. m/a to full charge.
1 60 426 2192
2 53 413 2219
3 54 421 2175
4 54.5 407 2166
5 63 385 2153
6 54 375 2126
7 47.5 368 1780
8 53.5 388 2188
9 52.5 385 2022
10 45.7 369 1912
11 45.2 398 2164

Cell 7 and cell 10 certainly look suspect in their recharging capacity, and cell 9 looks poor also. I would appreciate comments, and also, when I make up the pack, should I use 2p2s, or 2s2p, and if there is a preference, why?
Thanks.
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Old May 30, 2012, 01:30 PM
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I know the "proper" way to assess the SOC for these A123s is to see how much goes back in after a few flights, and the discharge curve is worryingly flat, but with receiver pack voltage monitoring /alarm through my Spektrum telemetry modules, I wonder if there's some mileage in using it on the A123s.
Im thinking perhaps a warning at 2.5V per cell ?
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Old May 30, 2012, 07:20 PM
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Way too low.
Pete
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Old May 31, 2012, 04:43 PM
k2k
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United States, CA, Oceanside
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I agree, way too low. I have flown gliders with a vario which reports voltage for several years and most of the time it reports 6.6 or 6.5 volts. When I hear 6.4 volts I start to get nervous.

One problem with telemetry is the reporting of transient voltage sags. Good wiring from the battery to the receiver will minimize this but false alarms are still going to happen. When I hear a low voltage report from my vario, I let things settle down for a few seconds then request another voltage report. If it is not back up to normal it is time to land. The false alarms will drive you crazy at first.

The best thing to do is to set the alarm threshold pretty high at first and see what happens. React to the alarm and charge the battery to see where you're at, then go from there.
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