Charging Nicad Batteries long-time flying buddy Karl Birkel left New York rat-race write letters about flying afternoon 6-mile-long strip near Port Charlotte FL has some encouraging things say about column also requested some good words about charging Nicads Since good friends dont come along very often must honor request Judging newsletters subject warrants review Nicad batteries fairly tough items being made chiefly metal used within limitations will yield charge/discharge cycles usually anywhere 1000 30000 depending service conditions things FIG 1 CELL UNBALANCE IN FLIGHT PACK 15 10 J2 I-J 0 -Jo w U 05 0 Technique will reduce battery life High tempera- George M Myers tures time overstress due charging discharging too high rate mechanical damage due shock vibration persistent usage very low states charge Taking opposite view ways prolong useful life Nicads keep cool use youve got charge discharge rates appropriate design later protect shock vibration use foam padding dont crash keep charging regularly whether use dont lie around discharged Ive avoiding subject Nicads some time because felt beaten flat during recent surge battery dischargers onto market Most letters have received requested building instructions either Fast Chargers 15-minute kind Standby all-winter Chargers other hand go field find peo ple generally have battery packs chargers what really think need enough chargers thing once says something about difference between letter-writers talkers Im sure what Lets start defining four types chargers generally recognized review characteristics names given vary manufacturer Im going use names assigned General Electric Company basis RC systems am familiar use GE products Fast Chargers chargers will com pletely charge discharged pack less hour usually require some kind control insure cells damaged charger controls take form temperature sensor bur ied pack voltage sensor measures power put pack starting fully discharged condi tion finally pressure sensor cell indicate cell has gone overcharge evidenced rise cell pressure common concern fast charging schemes possible damage 40506070 overcharging due rapid evolution gases within cell should used near room temperature sintered-plate ventable Nicads Quick Chargers chargers will charge fully discharged pack three six hours Due lower charge rates pressure rise overcharge region slower therefore charging con trollable timed basis GE makes spe cial cells quick charging made slightly larger heavier given capacity common slow charge cells greater size lets stand up temperature effects quick charging graceully other types temperature major con cern class charger Slow Chargers class charger familiar since type supplied RC system manufacturers Charging times range 10 24 hours 16-hour charge has become practically standard Pressure temperature rises overcharge range low enough THIS KIND OF SPREAD IS PROBABLY DUE TO TEST TECHNIQUE THE CELLS ARE OK 3 2 AND SHOULD BE REPLACED II 0102030 DISCHARGE TIME TES FIG 2 SIMPLE TOOL FOR FAST CHARGING AT THE FIELD DC VOLTS DE VOLTS BY lOTO READ AMPS 5 VOLTS MP CHARGING PLUG AND JACK 14 Model Aviation TYPICAL DISCHARGE CURVES CAD PACK maH recombination elements within cell can take care problem spite prolonged overcharging advan tages method Lowest cost cells charger freedom elaborate charging controls ability bring cells multi-cell pack highest possible individual states charge last point important because multi-cell pack such use possible cell become fully discharged remaining cells delivering significant current through re verse charging effect reduces total power available pack can lead early failure reversed cell Slow charging best way avoid problem reversed charging manufacturers provide packs quick fast charging must assemble cells carefully matched capacity Most packs supplied RC manufactur ers pretty well balanced buy become unbalanced age Standby Chargers class charger set fully charge discharged cell week less rate too low effi ciently charge battery pack nec essary first charge fully other means above commercial chargers available service usually part some emergency device such fire-warning burglar alarms Most often operate twostep mode providing slow quick charg ing whenever batteries used reverting standby rate cells fully recharged Fast Charger Recognizing limitations put forth above may want build fast quick charger circuits provided other magazines used proper understanding can effective risks can controlled However fore start using would good idea slow-charge pack discharge connecting 10-ohm 10watt resistor between red k s Open up pack can monitor voltage cell inde pendently Write down cell voltage 10-minute intervals until least cell has dropped 05 volts Fig 1 find cells has less capacity others pack repeat charging test still weak re place unbalance cells can significant problem build up pack surplus other cheap cells Usually such cells have passed 10-year shelf life limit theyare liable have high variable internal resist ances subject should never fast charge flat button cells nor cell has constructed some kind venting provision emergency might use de vice shown Fig 2 field charge flight need plug match continued page 80 FIG 3 ADAPTER FOR CONVERTING CALCULATOR CHARGER OR AC ADAPTER INTO FLIGHT PACK SLOW STANDBY CHARGER THE TIP IS USUALLY POSITIVE BUT CHECK IT 135V LED 110 VAC ..IIZZ1Z PLUGCALCULATORMINIATURER CHARGER ORPHONE JACK AC ADAPTERTO MATCHPLUG TO MATCH THE CALCULATOR JACK ON ITEM TO BE CHARGED C 0 z w 0 z C ci w 1000 500 0 SLOW CHARGE AT 05 AMPS 7891011 OPEN CIRCUIT VOLTAGE OF CALCULATOR CHARGER October1976 15 PICK VALUE OF R FROM GRAPH AT LEFT CHECK CURRENT INTO FULLY-CHARGED PACK BY MEASURING VOLTAGE ACROSS R AND CALCULATING CHARGING AMPS _ VOLTS ACROSS R R IN OHMS ADJUST VALUE OF R TO SUIT YOUR PARTICULAR COMPONENTS IF NECESSARY MINIMUM RESISTANCE 22 OHMS 12 Top photo Fig 4A relates Fig 2 op posite page Just above Fig 48 relates Fig 3 top page Radio Technique/Myers continued page 15 charging jack flight pack some wire two clips 10-ohm 10-watt resistor Connect ween flight pack 12-volt bat tery charge 15 minutes should put about 1/3 full charge enough tie-breaking contest flight Keep resistor away fingers inflam mables because gets hot Depending transmitter pack wired same device can used 15 minutes per 4-cell 450-maH assumed pack 30 minutes per 8-cell pack can monitor charging current connecting multimeter across 10-ohm resistor read ing volts divided 105 volts 05 amps may use rig discharge test described above Mickey Mouse turns off should read little further description Astro Flight Inc R/C System AnalyzerRapid Charger Slow Charger Most have now some kind pocket calculator Usually accom panied some kind AC adapter charger rated 6 7 9 volts DC 50 100 milliamps An LED resistor built top medicine bottle Fig 3 makes up device converts calculator tool either extra charger spare flight pack standby charger flight pack really feel need changes series limiting resistor Remember standby chargers built up memory probably thing does memory gets shorter time goes really dont advise use standby chargers insist LED diode will rectify convert AC DC well light show passage current will work adapter re gardless output calculator adapter main thing remember want charge ro Flight R/C System AnalyzerRapid Charger Mr Bob Boucher president Astro Flight Inc well known electric motors accessories have made practical electric-powered flight available modeling fraternity time interested R/C System AnalyzerRapid Charger Fig 5 must admit first got hands really didnt understand what tool came fine set instructions like people wanted know particular have experimenting fast chargers some time mind filled possibilities caus ing catastrophic cell failures spelled out battery manufacturers engineering handbooks letter Astro Flight precipitated phone call Bob made understand tool covered US patent 3957230 con servatively designed device will harm batteries will follow instructions reality device contains two tools case sharing use panel meter timer connecting cords Analyzer meter resistor series load battery pack actually senses rise internal resistance char acteristic Nicad pack approach ing 90% discharged state Typically change about 005 05 ohms shows meter defi nite reduction discharge current Prior reaching 90% discharged point current falls very slowly actual resistances battery packs varies somewhat according manufacturer Nicad cells current point sudden fall occurs may vary 175 20 amps Kraft KB 4E packs have four years hard use kicked over about 18 amps just last Saturday flew way through gallon fuel glitch out recharge use voltage-indicating pilot light try remember check after flight didnt have pilot light Analyzer would quickly give indication battery charge re maining because shows current avail able under load equivalent four stalled servos unlikely state affairs bodys airplane second tool Rapid Charger useable either transmitter receiver both same time Charging current tapers off exponentially auto matically safe charge partiallydischarged pack 15 minutes tool Fifteen minutes can put up 70% approximately full charge bat teries can tolerate equivalent over charge unnecessary charging 15 minutes about about 25% overcharge room temperature distress order put afull charge compktely discharged pack use two 15-minute charges right after other Since kind charging heats up battery pack fast charging does faster would good idea give pack few minutes cool between cycles going full charge Under normal circumstances 15-minute cy cle should enough anyone Now warning Three row No-No Actually put two night before third morning after batteries chance cool down nothing likely happen let heat pressure build up youll probably cause battery vent Thats very important batteries re-sealable vents type vents puncturing membrane will rapidly become useless rate analyzer section will tell you make such mistake instructions come device explain use detect shorted high-resistance cells bat tery packs determine charge remaining after days flying can also use determine charge capacity Flite Life Tower 200 etc perform deep-discharge full-recharge cycling packs may require after few months inactivity restore full charge capability also referred breaking memory last case full cycle would take 45 minutes put off charging batteries until just after weather clears like will appreciate new freedom device can put life Contact dealer write Astro Flight Inc 13377 Beach Avenue Venice CA 90291 Im told Bridi Fast Charger built under Astro Flight Inc patent uses same principles although Ive never studied have ideas youd like see discussed column please contact 70 Froeh lich Farm Rd Hicksville NY 11801 80 Model Aviation Fig 5 Astro Flight Analyzer-Rapid Charger right belongsbetween 1 2V battery transmitter receiving fast charge
Edition: Model Aviation - 1976/10
Page Numbers: 14, 15, 80
Charging Nicad Batteries long-time flying buddy Karl Birkel left New York rat-race write letters about flying afternoon 6-mile-long strip near Port Charlotte FL has some encouraging things say about column also requested some good words about charging Nicads Since good friends dont come along very often must honor request Judging newsletters subject warrants review Nicad batteries fairly tough items being made chiefly metal used within limitations will yield charge/discharge cycles usually anywhere 1000 30000 depending service conditions things FIG 1 CELL UNBALANCE IN FLIGHT PACK 15 10 J2 I-J 0 -Jo w U 05 0 Technique will reduce battery life High tempera- George M Myers tures time overstress due charging discharging too high rate mechanical damage due shock vibration persistent usage very low states charge Taking opposite view ways prolong useful life Nicads keep cool use youve got charge discharge rates appropriate design later protect shock vibration use foam padding dont crash keep charging regularly whether use dont lie around discharged Ive avoiding subject Nicads some time because felt beaten flat during recent surge battery dischargers onto market Most letters have received requested building instructions either Fast Chargers 15-minute kind Standby all-winter Chargers other hand go field find peo ple generally have battery packs chargers what really think need enough chargers thing once says something about difference between letter-writers talkers Im sure what Lets start defining four types chargers generally recognized review characteristics names given vary manufacturer Im going use names assigned General Electric Company basis RC systems am familiar use GE products Fast Chargers chargers will com pletely charge discharged pack less hour usually require some kind control insure cells damaged charger controls take form temperature sensor bur ied pack voltage sensor measures power put pack starting fully discharged condi tion finally pressure sensor cell indicate cell has gone overcharge evidenced rise cell pressure common concern fast charging schemes possible damage 40506070 overcharging due rapid evolution gases within cell should used near room temperature sintered-plate ventable Nicads Quick Chargers chargers will charge fully discharged pack three six hours Due lower charge rates pressure rise overcharge region slower therefore charging con trollable timed basis GE makes spe cial cells quick charging made slightly larger heavier given capacity common slow charge cells greater size lets stand up temperature effects quick charging graceully other types temperature major con cern class charger Slow Chargers class charger familiar since type supplied RC system manufacturers Charging times range 10 24 hours 16-hour charge has become practically standard Pressure temperature rises overcharge range low enough THIS KIND OF SPREAD IS PROBABLY DUE TO TEST TECHNIQUE THE CELLS ARE OK 3 2 AND SHOULD BE REPLACED II 0102030 DISCHARGE TIME TES FIG 2 SIMPLE TOOL FOR FAST CHARGING AT THE FIELD DC VOLTS DE VOLTS BY lOTO READ AMPS 5 VOLTS MP CHARGING PLUG AND JACK 14 Model Aviation TYPICAL DISCHARGE CURVES CAD PACK maH recombination elements within cell can take care problem spite prolonged overcharging advan tages method Lowest cost cells charger freedom elaborate charging controls ability bring cells multi-cell pack highest possible individual states charge last point important because multi-cell pack such use possible cell become fully discharged remaining cells delivering significant current through re verse charging effect reduces total power available pack can lead early failure reversed cell Slow charging best way avoid problem reversed charging manufacturers provide packs quick fast charging must assemble cells carefully matched capacity Most packs supplied RC manufactur ers pretty well balanced buy become unbalanced age Standby Chargers class charger set fully charge discharged cell week less rate too low effi ciently charge battery pack nec essary first charge fully other means above commercial chargers available service usually part some emergency device such fire-warning burglar alarms Most often operate twostep mode providing slow quick charg ing whenever batteries used reverting standby rate cells fully recharged Fast Charger Recognizing limitations put forth above may want build fast quick charger circuits provided other magazines used proper understanding can effective risks can controlled However fore start using would good idea slow-charge pack discharge connecting 10-ohm 10watt resistor between red k s Open up pack can monitor voltage cell inde pendently Write down cell voltage 10-minute intervals until least cell has dropped 05 volts Fig 1 find cells has less capacity others pack repeat charging test still weak re place unbalance cells can significant problem build up pack surplus other cheap cells Usually such cells have passed 10-year shelf life limit theyare liable have high variable internal resist ances subject should never fast charge flat button cells nor cell has constructed some kind venting provision emergency might use de vice shown Fig 2 field charge flight need plug match continued page 80 FIG 3 ADAPTER FOR CONVERTING CALCULATOR CHARGER OR AC ADAPTER INTO FLIGHT PACK SLOW STANDBY CHARGER THE TIP IS USUALLY POSITIVE BUT CHECK IT 135V LED 110 VAC ..IIZZ1Z PLUGCALCULATORMINIATURER CHARGER ORPHONE JACK AC ADAPTERTO MATCHPLUG TO MATCH THE CALCULATOR JACK ON ITEM TO BE CHARGED C 0 z w 0 z C ci w 1000 500 0 SLOW CHARGE AT 05 AMPS 7891011 OPEN CIRCUIT VOLTAGE OF CALCULATOR CHARGER October1976 15 PICK VALUE OF R FROM GRAPH AT LEFT CHECK CURRENT INTO FULLY-CHARGED PACK BY MEASURING VOLTAGE ACROSS R AND CALCULATING CHARGING AMPS _ VOLTS ACROSS R R IN OHMS ADJUST VALUE OF R TO SUIT YOUR PARTICULAR COMPONENTS IF NECESSARY MINIMUM RESISTANCE 22 OHMS 12 Top photo Fig 4A relates Fig 2 op posite page Just above Fig 48 relates Fig 3 top page Radio Technique/Myers continued page 15 charging jack flight pack some wire two clips 10-ohm 10-watt resistor Connect ween flight pack 12-volt bat tery charge 15 minutes should put about 1/3 full charge enough tie-breaking contest flight Keep resistor away fingers inflam mables because gets hot Depending transmitter pack wired same device can used 15 minutes per 4-cell 450-maH assumed pack 30 minutes per 8-cell pack can monitor charging current connecting multimeter across 10-ohm resistor read ing volts divided 105 volts 05 amps may use rig discharge test described above Mickey Mouse turns off should read little further description Astro Flight Inc R/C System AnalyzerRapid Charger Slow Charger Most have now some kind pocket calculator Usually accom panied some kind AC adapter charger rated 6 7 9 volts DC 50 100 milliamps An LED resistor built top medicine bottle Fig 3 makes up device converts calculator tool either extra charger spare flight pack standby charger flight pack really feel need changes series limiting resistor Remember standby chargers built up memory probably thing does memory gets shorter time goes really dont advise use standby chargers insist LED diode will rectify convert AC DC well light show passage current will work adapter re gardless output calculator adapter main thing remember want charge ro Flight R/C System AnalyzerRapid Charger Mr Bob Boucher president Astro Flight Inc well known electric motors accessories have made practical electric-powered flight available modeling fraternity time interested R/C System AnalyzerRapid Charger Fig 5 must admit first got hands really didnt understand what tool came fine set instructions like people wanted know particular have experimenting fast chargers some time mind filled possibilities caus ing catastrophic cell failures spelled out battery manufacturers engineering handbooks letter Astro Flight precipitated phone call Bob made understand tool covered US patent 3957230 con servatively designed device will harm batteries will follow instructions reality device contains two tools case sharing use panel meter timer connecting cords Analyzer meter resistor series load battery pack actually senses rise internal resistance char acteristic Nicad pack approach ing 90% discharged state Typically change about 005 05 ohms shows meter defi nite reduction discharge current Prior reaching 90% discharged point current falls very slowly actual resistances battery packs varies somewhat according manufacturer Nicad cells current point sudden fall occurs may vary 175 20 amps Kraft KB 4E packs have four years hard use kicked over about 18 amps just last Saturday flew way through gallon fuel glitch out recharge use voltage-indicating pilot light try remember check after flight didnt have pilot light Analyzer would quickly give indication battery charge re maining because shows current avail able under load equivalent four stalled servos unlikely state affairs bodys airplane second tool Rapid Charger useable either transmitter receiver both same time Charging current tapers off exponentially auto matically safe charge partiallydischarged pack 15 minutes tool Fifteen minutes can put up 70% approximately full charge bat teries can tolerate equivalent over charge unnecessary charging 15 minutes about about 25% overcharge room temperature distress order put afull charge compktely discharged pack use two 15-minute charges right after other Since kind charging heats up battery pack fast charging does faster would good idea give pack few minutes cool between cycles going full charge Under normal circumstances 15-minute cy cle should enough anyone Now warning Three row No-No Actually put two night before third morning after batteries chance cool down nothing likely happen let heat pressure build up youll probably cause battery vent Thats very important batteries re-sealable vents type vents puncturing membrane will rapidly become useless rate analyzer section will tell you make such mistake instructions come device explain use detect shorted high-resistance cells bat tery packs determine charge remaining after days flying can also use determine charge capacity Flite Life Tower 200 etc perform deep-discharge full-recharge cycling packs may require after few months inactivity restore full charge capability also referred breaking memory last case full cycle would take 45 minutes put off charging batteries until just after weather clears like will appreciate new freedom device can put life Contact dealer write Astro Flight Inc 13377 Beach Avenue Venice CA 90291 Im told Bridi Fast Charger built under Astro Flight Inc patent uses same principles although Ive never studied have ideas youd like see discussed column please contact 70 Froeh lich Farm Rd Hicksville NY 11801 80 Model Aviation Fig 5 Astro Flight Analyzer-Rapid Charger right belongsbetween 1 2V battery transmitter receiving fast charge
Edition: Model Aviation - 1976/10
Page Numbers: 14, 15, 80
Charging Nicad Batteries long-time flying buddy Karl Birkel left New York rat-race write letters about flying afternoon 6-mile-long strip near Port Charlotte FL has some encouraging things say about column also requested some good words about charging Nicads Since good friends dont come along very often must honor request Judging newsletters subject warrants review Nicad batteries fairly tough items being made chiefly metal used within limitations will yield charge/discharge cycles usually anywhere 1000 30000 depending service conditions things FIG 1 CELL UNBALANCE IN FLIGHT PACK 15 10 J2 I-J 0 -Jo w U 05 0 Technique will reduce battery life High tempera- George M Myers tures time overstress due charging discharging too high rate mechanical damage due shock vibration persistent usage very low states charge Taking opposite view ways prolong useful life Nicads keep cool use youve got charge discharge rates appropriate design later protect shock vibration use foam padding dont crash keep charging regularly whether use dont lie around discharged Ive avoiding subject Nicads some time because felt beaten flat during recent surge battery dischargers onto market Most letters have received requested building instructions either Fast Chargers 15-minute kind Standby all-winter Chargers other hand go field find peo ple generally have battery packs chargers what really think need enough chargers thing once says something about difference between letter-writers talkers Im sure what Lets start defining four types chargers generally recognized review characteristics names given vary manufacturer Im going use names assigned General Electric Company basis RC systems am familiar use GE products Fast Chargers chargers will com pletely charge discharged pack less hour usually require some kind control insure cells damaged charger controls take form temperature sensor bur ied pack voltage sensor measures power put pack starting fully discharged condi tion finally pressure sensor cell indicate cell has gone overcharge evidenced rise cell pressure common concern fast charging schemes possible damage 40506070 overcharging due rapid evolution gases within cell should used near room temperature sintered-plate ventable Nicads Quick Chargers chargers will charge fully discharged pack three six hours Due lower charge rates pressure rise overcharge region slower therefore charging con trollable timed basis GE makes spe cial cells quick charging made slightly larger heavier given capacity common slow charge cells greater size lets stand up temperature effects quick charging graceully other types temperature major con cern class charger Slow Chargers class charger familiar since type supplied RC system manufacturers Charging times range 10 24 hours 16-hour charge has become practically standard Pressure temperature rises overcharge range low enough THIS KIND OF SPREAD IS PROBABLY DUE TO TEST TECHNIQUE THE CELLS ARE OK 3 2 AND SHOULD BE REPLACED II 0102030 DISCHARGE TIME TES FIG 2 SIMPLE TOOL FOR FAST CHARGING AT THE FIELD DC VOLTS DE VOLTS BY lOTO READ AMPS 5 VOLTS MP CHARGING PLUG AND JACK 14 Model Aviation TYPICAL DISCHARGE CURVES CAD PACK maH recombination elements within cell can take care problem spite prolonged overcharging advan tages method Lowest cost cells charger freedom elaborate charging controls ability bring cells multi-cell pack highest possible individual states charge last point important because multi-cell pack such use possible cell become fully discharged remaining cells delivering significant current through re verse charging effect reduces total power available pack can lead early failure reversed cell Slow charging best way avoid problem reversed charging manufacturers provide packs quick fast charging must assemble cells carefully matched capacity Most packs supplied RC manufactur ers pretty well balanced buy become unbalanced age Standby Chargers class charger set fully charge discharged cell week less rate too low effi ciently charge battery pack nec essary first charge fully other means above commercial chargers available service usually part some emergency device such fire-warning burglar alarms Most often operate twostep mode providing slow quick charg ing whenever batteries used reverting standby rate cells fully recharged Fast Charger Recognizing limitations put forth above may want build fast quick charger circuits provided other magazines used proper understanding can effective risks can controlled However fore start using would good idea slow-charge pack discharge connecting 10-ohm 10watt resistor between red k s Open up pack can monitor voltage cell inde pendently Write down cell voltage 10-minute intervals until least cell has dropped 05 volts Fig 1 find cells has less capacity others pack repeat charging test still weak re place unbalance cells can significant problem build up pack surplus other cheap cells Usually such cells have passed 10-year shelf life limit theyare liable have high variable internal resist ances subject should never fast charge flat button cells nor cell has constructed some kind venting provision emergency might use de vice shown Fig 2 field charge flight need plug match continued page 80 FIG 3 ADAPTER FOR CONVERTING CALCULATOR CHARGER OR AC ADAPTER INTO FLIGHT PACK SLOW STANDBY CHARGER THE TIP IS USUALLY POSITIVE BUT CHECK IT 135V LED 110 VAC ..IIZZ1Z PLUGCALCULATORMINIATURER CHARGER ORPHONE JACK AC ADAPTERTO MATCHPLUG TO MATCH THE CALCULATOR JACK ON ITEM TO BE CHARGED C 0 z w 0 z C ci w 1000 500 0 SLOW CHARGE AT 05 AMPS 7891011 OPEN CIRCUIT VOLTAGE OF CALCULATOR CHARGER October1976 15 PICK VALUE OF R FROM GRAPH AT LEFT CHECK CURRENT INTO FULLY-CHARGED PACK BY MEASURING VOLTAGE ACROSS R AND CALCULATING CHARGING AMPS _ VOLTS ACROSS R R IN OHMS ADJUST VALUE OF R TO SUIT YOUR PARTICULAR COMPONENTS IF NECESSARY MINIMUM RESISTANCE 22 OHMS 12 Top photo Fig 4A relates Fig 2 op posite page Just above Fig 48 relates Fig 3 top page Radio Technique/Myers continued page 15 charging jack flight pack some wire two clips 10-ohm 10-watt resistor Connect ween flight pack 12-volt bat tery charge 15 minutes should put about 1/3 full charge enough tie-breaking contest flight Keep resistor away fingers inflam mables because gets hot Depending transmitter pack wired same device can used 15 minutes per 4-cell 450-maH assumed pack 30 minutes per 8-cell pack can monitor charging current connecting multimeter across 10-ohm resistor read ing volts divided 105 volts 05 amps may use rig discharge test described above Mickey Mouse turns off should read little further description Astro Flight Inc R/C System AnalyzerRapid Charger Slow Charger Most have now some kind pocket calculator Usually accom panied some kind AC adapter charger rated 6 7 9 volts DC 50 100 milliamps An LED resistor built top medicine bottle Fig 3 makes up device converts calculator tool either extra charger spare flight pack standby charger flight pack really feel need changes series limiting resistor Remember standby chargers built up memory probably thing does memory gets shorter time goes really dont advise use standby chargers insist LED diode will rectify convert AC DC well light show passage current will work adapter re gardless output calculator adapter main thing remember want charge ro Flight R/C System AnalyzerRapid Charger Mr Bob Boucher president Astro Flight Inc well known electric motors accessories have made practical electric-powered flight available modeling fraternity time interested R/C System AnalyzerRapid Charger Fig 5 must admit first got hands really didnt understand what tool came fine set instructions like people wanted know particular have experimenting fast chargers some time mind filled possibilities caus ing catastrophic cell failures spelled out battery manufacturers engineering handbooks letter Astro Flight precipitated phone call Bob made understand tool covered US patent 3957230 con servatively designed device will harm batteries will follow instructions reality device contains two tools case sharing use panel meter timer connecting cords Analyzer meter resistor series load battery pack actually senses rise internal resistance char acteristic Nicad pack approach ing 90% discharged state Typically change about 005 05 ohms shows meter defi nite reduction discharge current Prior reaching 90% discharged point current falls very slowly actual resistances battery packs varies somewhat according manufacturer Nicad cells current point sudden fall occurs may vary 175 20 amps Kraft KB 4E packs have four years hard use kicked over about 18 amps just last Saturday flew way through gallon fuel glitch out recharge use voltage-indicating pilot light try remember check after flight didnt have pilot light Analyzer would quickly give indication battery charge re maining because shows current avail able under load equivalent four stalled servos unlikely state affairs bodys airplane second tool Rapid Charger useable either transmitter receiver both same time Charging current tapers off exponentially auto matically safe charge partiallydischarged pack 15 minutes tool Fifteen minutes can put up 70% approximately full charge bat teries can tolerate equivalent over charge unnecessary charging 15 minutes about about 25% overcharge room temperature distress order put afull charge compktely discharged pack use two 15-minute charges right after other Since kind charging heats up battery pack fast charging does faster would good idea give pack few minutes cool between cycles going full charge Under normal circumstances 15-minute cy cle should enough anyone Now warning Three row No-No Actually put two night before third morning after batteries chance cool down nothing likely happen let heat pressure build up youll probably cause battery vent Thats very important batteries re-sealable vents type vents puncturing membrane will rapidly become useless rate analyzer section will tell you make such mistake instructions come device explain use detect shorted high-resistance cells bat tery packs determine charge remaining after days flying can also use determine charge capacity Flite Life Tower 200 etc perform deep-discharge full-recharge cycling packs may require after few months inactivity restore full charge capability also referred breaking memory last case full cycle would take 45 minutes put off charging batteries until just after weather clears like will appreciate new freedom device can put life Contact dealer write Astro Flight Inc 13377 Beach Avenue Venice CA 90291 Im told Bridi Fast Charger built under Astro Flight Inc patent uses same principles although Ive never studied have ideas youd like see discussed column please contact 70 Froeh lich Farm Rd Hicksville NY 11801 80 Model Aviation Fig 5 Astro Flight Analyzer-Rapid Charger right belongsbetween 1 2V battery transmitter receiving fast charge