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FanFacts W


elcome back! I trust that all of you have been able to commit massive amounts of aviation over the last month and that


your “needed” workshop time has been minimal! As I write this in the later part of May,


with the winds howling at 48 mph, gusting to 70 (no flying for me today!) I had to pause and think about the last time I flew, three weeks ago, and the issues several folks had with their equipment. Several guys had switched to Li-Fe battery technology (sever- al different manufacturers) and were having problems with their batteries failing. Please remember that you must use an Li-Fe capa- ble charger, whether the excellent Li-Fe/ A123 specific charger from Astroflight, or a multicharger like those from Bantam, FMA, Hyperion, Hitec and many others. While Ni-Cd and Ni-MH cells are not im-


mune to charging errors (I’ve witnessed charging fires with both chemistries) they do seem to allow greater latitude in charg- ing than the Lithium chemistries do. So, if you are having problems with your batter- ies, don’t blame their manufacturer and chemistry into perdition until you have checked your charging protocols since crow usually doesn’t taste very good (especially during barbeque season). Another thing I noted was newer Li-Fe


users using their “good-ol voltage meter” to check their receiver packs voltage under load. The problem being that the cells put out 6.6 volts under standard voltage tester loads up until they hit the “elbow” and they then fall off precipitously, with the possibil- ity of a re-kitting event increasing without the owner even knowing it. While a loaded voltmeter with its red and green zones gives great info for Ni-Cd and Ni-MH cells, it doesn’t work for Lithium. So the answer is fly a flight or two, recharge and note the number of milliamps put back into the pack. Very simple math tells you the number of milliamps used per flight, and how many you can safely get by not exceeding 75% of the pack’s capacity. One habit that I developed many years


ago (following the loss of an airplane from battery failure), was to keep a record of the number of milliamps put back in during pe- riodic discharge/charge cycles. The problem was/is that I didn’t have a routine time of the year to do this, and I didn’t keep the data in a spreadsheet format—I’m simplistic and wrote it on the battery pack! Well, my method is well and good, but it requires the pack to be removed from the airplane to see what the previous charge levels were. Taking things to the next level, Lance Campbell (JPO’s District VI rep) described in the Spring 2012 issue of Contrails how he cycles his packs three times each year, with three discharge/charge cycles each time, and then charts the actual numbers. This data gives you the information you need to be very aware about your pack’s health. Additionally, he uses FMA’s CellPro 4S


26 Battery


14 Ch Tx Charge


New July '09 New Spring '11


F-15 Rec Discharge A123 2 Cell New Fall '10


F-15 Ecu Discharge A123 3 Cell New Fall '10


F-15 Smoke Discharge A123 2 Cell New Fall '10


Mar 09


by greg moore You can reach Greg Moore via e-mail at jetflyr@comcast.net


Battery Maintenance Actual mAh delivered


Date Volts Rated Time 1 Time 2 Time 3 % of life Nov 08 7.4 2200


July 09 7.4 2200 Mar 10


July 10 7.4 2200 Nov 11 7.4 2200 Mar 12


7.4 2200 Mar 10


7.4 2200 7.4 2200


x x x x x x x


x x x x x x x


2250 102.3% 2197 2196 2126 2020 2189 2054


99.9% 99.8% 96.6% 91.8% 99.5% 93.4%


6.6 2300 2171 2194 2195


July 10 6.6 2300 2156 2177 2184 Nov 10 6.6 2300 2109 2101 2148 Nov 11 6.6 2300 2082 2104 2126 Mar 12


Mar 10


6.6 2300 2086 2096 2097 9.9 2300 2148 2158 2179


July 10 9.9 2300 2221 2134 2140 Nov 10 9.9 2300 2091 2111 2128 Nov 11 9.9 2300 2047 2097 2088 Mar 12


Mar 10


9.9 2300 2041 2076 2084 6.6 2300 2172 2166 2172


July 10 6.6 2300 2125 2166 2170 Nov 10 6.6 2300 2100 2093 2119 Nov 11 6.6 2300 2052 2080 2077 Mar 12


6.6 2300 2050 2067 2089


95.4% 95.0% 93.4% 92.4% 91.2%


94.7% 93.0% 92.5% 90.8% 90.6%


94.4% 94.3% 92.1% 90.3% 90.8%


While a little long, this table (above) shows that only one of the packs Lance Campbell has monitored equaled, or exceeded its rated capacity. The other packs, while not reaching the rated capacity are still in very good shape as can be seen by the percentage of capacity they are all maintaining. This screen shot (below) of a graphed 3S battery pack (from an FMA CellPro 4S charger) shows the minor differences of the three cells. In Greg’s mind this is a valuable tool in monitoring your batteries’ health.


CELL VOLTAGE CELL 1 CELL 2 CELL 3 3.658V 3.484V 3.3098V 3.135V 3.960V 0.0 4.5 9.0 13 18


Preset Name: A123 2300 mAh Accurate Charge Set 4.00A BAL Chg Time Started: 10:06:25 10-08-2011 Start Fuel: Pack 1 = 0% Pack 1: 2034 mAh IN Cell 1 Cell 2 Cell 3


Firmware: V1.67


charger which allows the charger to be con- nected to your computer in order to graph the charge curve of each cell, which can be very valuable both in maintaining the health of the pack and the health of the airplane! My West Mountains charger will graph a pack, but not each cell, which in a receiv- er/transmitter configuration, I now think is needed. Oh boy, I now get to contemplate the purchase of yet another charger! Changing topics, I have said (over and


over to myself) that the ARF on my bench getting reinforcements, re-designed parts, different hardware and so on is not a “mi- crowave ready meal” type of project, it is just a highly prefabricated kit. Otherwise I go crazy thinking about why it is taking me so long, debating/second guessing myself on why I am modifying a structure or changing hardware and on-and-on. Therefore, it was nice to see the following comment posted on an internet forum


AUGUST 2012 22 Charge Minutes 27 31 36 40


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