---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 01/02/18: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:36 AM - Re: Battery, Alternator, CB (Robert L. Nuckolls, III) 2. 07:28 AM - Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator (Jared Yates) 3. 08:03 AM - Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator (Kent or Jackie Ashton) 4. 08:13 AM - Re: Battery, Alternator, CB (Bernie) 5. 08:31 AM - Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator (Charlie England) 6. 09:02 AM - Tech Edge "MODA" Fuel Level Probe (William Hunter) 7. 09:26 AM - Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator (Jared Yates) 8. 09:58 AM - Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator (Charlie England) 9. 10:23 AM - Re: Battery, Alternator, CB (Robert L. Nuckolls, III) 10. 10:27 AM - Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind (user9253) 11. 01:35 PM - Re: Battery, Alternator, CB (Charlie England) 12. 01:56 PM - Re: Battery, Alternator, CB (Eric Page) 13. 01:57 PM - Product Alert (Robert L. Nuckolls, III) 14. 02:16 PM - Re: Battery, Alternator, CB (Robert L. Nuckolls, III) 15. 02:30 PM - Re: Battery, Alternator, CB (Charlie England) 16. 02:36 PM - Re: Product Alert (Eric Page) 17. 06:34 PM - Re: Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind (Charlie England) 18. 07:18 PM - Re: Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind (Jared Yates) ________________________________ Message 1 _____________________________________ Time: 03:36:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Battery, Alternator, CB At 05:01 PM 1/1/2018, you wrote: > >Happy New Year! > >The quest for understanding continues: Here=99s >the issue - A recent post described a situation >where a field switch CB had been opened in >flight accidentally and the battery had run >down. When it was discovered and closed the >alternator came back on line but opened the >Alternator CB because it was rated less than the >charging rate of the alternator. So there was >no way to charge the battery. Hence the >recommendation to size the alternator CB to the >alternator capacity. But what about the battery capacity? > >I believe its true that the alternator puts out >is rated capacity whenever the field circuit >allows it to operate. So after engine start a >70 amp alternator rapidly recharges the battery >and the field circuit opens and closes to keep >the system up to the set voltage of say >14.2. I=99ve read elsewhere that the charging >rate should not be over 40% of the amp hour >capacity of the AGM batteries. So if I have a 70 >amp alternator and a 35 amp hour battery it >looks like it won=99t last very long because of too high a rate of charging. > >Do I understand what I=99m writing about? Any suggestions? The alternator b-lead breaker protects the b-lead wire . . . it has no duties with respect to limiting output of the alternator. B-lead protection is best accomplished under the cowl with a current limiter (really FAT fuse) thus keeping the alternator's b-lead out of the cockpit. This has be common practice on TC aircraft for 50 years. That admonition for limiting recharge rate on ANY battery is the fondest fantasy of the battery designers . . . a condition that may well maximize battery service life in deep discharge applications but doesn't apply to service as a cranking battery in vehicles. Suggest you move your b-lead protection out to the firewall adjacent to the starter contactor as illustrated in Z13/8 https://goo.gl/BKufLb . . . and other z-figures. Protect with a current limiter rated for 50-70A. You can get miniature devices off eBay at reasonable prices . . . https://goo.gl/wG73m1 You can build a fuse holder with 10-32 or 1/4-28 hardware and some suitable base material. https://goo.gl/cMQtA4 For years during the changeover from generators to alternators, TC aircraft featured b-lead breakers on the panel DESIGNED to nuisance trip under certain conditions as explained in the narrative for Figure 17-2 of the 'Connection. Emacs! Current limiters are EXCEEDINGLY robust for their 'current carry ratings' . . . A 50A limiter will carry 90A indefinitely. But opens in about 300 milliseconds with a 200A load. Emacs! The battery-sources hard fault will be hundreds of amps . . . the current limiter will open very quickly while being immune to nuisance trips for normal, expected operating conditions. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:28:17 AM PST US From: Jared Yates Subject: AeroElectric-List: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator It's not good to initiate a takeoff with a 2-stroke engine that isn't warm enough, so I'd like to find or make a circuit that measures the temperature and extinguishes an LED when the temperature reaches a certain threshold. Preferably I'd like to adjust that threshold with software or a potentiometer. The result would be a "wait" light: start the engine, and don't take off until the LED is out. That would also function as a "you forgot to turn off the master" warning, after the flying is done. My first thought was a type K thermocouple measuring CHT under the spark plug, feeding to a hobbyist micro controller like this: https://learn.adafruit.com/introducing-trinket with a thermocouple amplifier like this: https://www.adafruit.com/product/1778 But since I'm only wanting a simple and binary wait/go indication rather than a readout in degrees, I wonder if the above plan is going a little overboard. The electrical system has an 18.5 volt battery for starting, with no onboard charging, so energy consumption is a minor consideration. Tiny size, durability, and reliability are high priorities. Does anyone have an idea for a simpler design, or better yet, is someone already selling one? ________________________________ Message 3 _____________________________________ Time: 08:03:07 AM PST US From: Kent or Jackie Ashton Subject: Re: AeroElectric-List: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator Jared, maybe you could substitute a small (about 10cm X 20cm) voltage meter as sold on ebay. Search for mini voltage meter. Youd have the additional advantage of being able to watch the warmup and you wouldnt have to calibrate an LED on-off setpoint. They are cheap, I gotta try that on my bike! -Kent > On Jan 2, 2018, at 10:27 AM, Jared Yates wrote: > > It's not good to initiate a takeoff with a 2-stroke engine that isn't warm enough, so I'd like to find or make a circuit that measures the temperature and extinguishes an LED when the temperature reaches a certain threshold. Preferably I'd like to adjust that threshold with software or a potentiometer. The result would be a "wait" light: start the engine, and don't take off until the LED is out. That would also function as a "you forgot to turn off the master" warning, after the flying is done. > > My first thought was a type K thermocouple measuring CHT under the spark plug, feeding to a hobbyist micro controller like this: > https://learn.adafruit.com/introducing-trinket > with a thermocouple amplifier like this: > https://www.adafruit.com/product/1778 > > But since I'm only wanting a simple and binary wait/go indication rather than a readout in degrees, I wonder if the above plan is going a little overboard. The electrical system has an 18.5 volt battery for starting, with no onboard charging, so energy consumption is a minor consideration. Tiny size, durability, and reliability are high priorities. > > Does anyone have an idea for a simpler design, or better yet, is someone already selling one? > ________________________________ Message 4 _____________________________________ Time: 08:13:45 AM PST US From: Bernie Subject: Re: AeroElectric-List: Battery, Alternator, CB Bob, Makes sense, ordered Aero Connection for a back up. Bernie Sent from my iPhone > On Jan 2, 2018, at 2:35 AM, Robert L. Nuckolls, III wrote: > > At 05:01 PM 1/1/2018, you wrote: .com> >> >> Happy New Year! >> >> The quest for understanding continues: Here=99s the issue - A rece nt post described a situation where a field switch CB had been opened in fli ght accidentally and the battery had run down. When it was discovered and c losed the alternator came back on line but opened the Alternator CB because i t was rated less than the charging rate of the alternator. So there was no w ay to charge the battery. Hence the recommendation to size the alternator C B to the alternator capacity. But what about the battery capacity? >> >> I believe its true that the alternator puts out is rated capacity wheneve r the field circuit allows it to operate. So after engine start a 70 amp al ternator rapidly recharges the battery and the field circuit opens and close s to keep the system up to the set voltage of say 14.2. I=99ve read e lsewhere that the charging rate should not be over 40% of the amp hour capac ity of the AGM batteries. So if I have a 70 amp alternator and a 35 amp hour battery it looks like it won=99t last very long because of too high a rate of charging. >> >> Do I understand what I=99m writing about? Any suggestions? > > The alternator b-lead breaker protects the b-lead > wire . . . it has no duties with respect to limiting > output of the alternator. B-lead protection is best > accomplished under the cowl with a current limiter > (really FAT fuse) thus keeping the alternator's > b-lead out of the cockpit. This has be common practice > on TC aircraft for 50 years. > > That admonition for limiting recharge rate on ANY > battery is the fondest fantasy of the battery > designers . . . a condition that may well maximize > battery service life in deep discharge applications > but doesn't apply to service as a cranking battery > in vehicles. > > Suggest you move your b-lead protection out to the > firewall adjacent to the starter contactor as illustrated > in Z13/8 > > https://goo.gl/BKufLb > > . . . and other z-figures. Protect with a current > limiter rated for 50-70A. You can get miniature > devices off eBay at reasonable prices . . . > > https://goo.gl/wG73m1 > > You can build a fuse holder with 10-32 or 1/4-28 > hardware and some suitable base material. > > https://goo.gl/cMQtA4 > > For years during the changeover from generators > to alternators, TC aircraft featured b-lead > breakers on the panel DESIGNED to nuisance > trip under certain conditions as explained in > the narrative for Figure 17-2 of the 'Connection. > > > > Current limiters are EXCEEDINGLY robust for their > 'current carry ratings' . . . A 50A limiter will > carry 90A indefinitely. But opens in about 300 > milliseconds with a 200A load. > > > > > The battery-sources hard fault will be hundreds of > amps . . . the current limiter will open very quickly > while being immune to nuisance trips for normal, expected > operating conditions. > > Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:31:25 AM PST US Subject: Re: AeroElectric-List: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator From: Charlie England On 1/2/2018 9:27 AM, Jared Yates wrote: > It's not good to initiate a takeoff with a 2-stroke engine that isn't > warm enough, so I'd like to find or make a circuit that measures the > temperature and extinguishes an LED when the temperature reaches a > certain threshold. Preferably I'd like to adjust that threshold with > software or a potentiometer. The result would be a "wait" light: start > the engine, and don't take off until the LED is out. That would also > function as a "you forgot to turn off the master" warning, after the > flying is done. > > My first thought was a type K thermocouple measuring CHT under the > spark plug, feeding to a hobbyist micro controller like this: > https://learn.adafruit.com/introducing-trinket > with a thermocouple amplifier like this: > https://www.adafruit.com/product/1778 > > But since I'm only wanting a simple and binary wait/go indication > rather than a readout in degrees, I wonder if the above plan is going > a little overboard. The electrical system has an 18.5 volt battery for > starting, with no onboard charging, so energy consumption is a minor > consideration. Tiny size, durability, and reliability are high priorities. > > Does anyone have an idea for a simpler design, or better yet, is > someone already selling one? > My 1st thought is that the 'forgot' mode probably won't be effective (at least for me), since it takes time for the heads to cool down. I know I'd be likely to walk away before the light came on. 2nd thought is that since I'd want CHT gauges anyway, why not just use them? I'd be sitting in the plane with the engine running, looking at the instruments, so why not just look at the CHT? No power required, no extra instrument. If you really want the light, an LM34 feeding a comparator circuit (op amp and some resistors) would work. Charlie --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 6 _____________________________________ Time: 09:02:04 AM PST US From: "William Hunter" Subject: AeroElectric-List: Tech Edge "MODA" Fuel Level Probe Hi All, I've been working like crazy on my project and am getting ready to fly soon!!! One obstacle (among many) is a solution to my header tank fuel level sensor. I have a 5 gallon fiberglass header tank that the two wing tanks gravity flow into and then the engine uses this header tank as its sole source of fuel so it is good to know if this header tank is full. It had an ON/OFF float switch however that switch is no longer working and I tried to unscrew the float switch to replace it however it is so tight that I am worried the plastic body/hex nut will break off so it is best at this point to just leave it installed as a "plug" and pursue another solution. Has anyone used a MODA tank sensor kit from tankedge.com ? https://tankedge.com/accessories.html It is a sensor that attaches to the outside of a fiberglass tank with dual parallel strips of aluminum and copper tape. Somehow it measures the resistance between the two strips and determines the fuel quantity on the other side of the tank wall. Since I have a fiberglass header tank I am interested in this system...IF...it will integrate with my Dynon Skyview. It seems like it should work just fine because it puts out a variable voltage from zero to 5.0 volts. Naturally I want it to work but I also want it to be durable in the long run so if anyone has any experience with this unit please do share. Here is a quote from a cyber friend who used it however he is not running a Dynon: Once it is set-up you give the sensor 12 volts, and then reads the blue wire for voltage based on the tank level from 0-5 V. Here were my values during my initial test: Voltage provided - 12.4 V Empty - 1.1V 1 Gal - 2.7 V 2 Gal - 3.8 V 3 Gal - 4.5 V 4 Gal - 4.7 V (didnt measure beyond this value) Moving metal objects nearby (like an aileron bell crank) can change the voltage by as much as .15V. It also responds well to moving the tank around attempting to simulate flying conditions with low fuel in the sump and sloshing fuel. .. As always THANKS FOR YOUR HELP and I will report back if I get this airplane to fly!!! Bill Hunter ________________________________ Message 7 _____________________________________ Time: 09:26:15 AM PST US From: Jared Yates Subject: Re: AeroElectric-List: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator Thanks Charlie, this is a foot launch ultralight with no panel, so pilot viewing space is especially premium. Does the LM34 need to be in contact with the cylinder? I wonder how to best accomplish that, mechanically speaking. On January 2, 2018 11:37:25 Charlie England wrote: > > On 1/2/2018 9:27 AM, Jared Yates wrote: >> It's not good to initiate a takeoff with a 2-stroke engine that isn't >> warm enough, so I'd like to find or make a circuit that measures the >> temperature and extinguishes an LED when the temperature reaches a >> certain threshold. Preferably I'd like to adjust that threshold with >> software or a potentiometer. The result would be a "wait" light: start >> the engine, and don't take off until the LED is out. That would also >> function as a "you forgot to turn off the master" warning, after the >> flying is done. >> >> My first thought was a type K thermocouple measuring CHT under the >> spark plug, feeding to a hobbyist micro controller like this: >> https://learn.adafruit.com/introducing-trinket >> with a thermocouple amplifier like this: >> https://www.adafruit.com/product/1778 >> >> But since I'm only wanting a simple and binary wait/go indication >> rather than a readout in degrees, I wonder if the above plan is going >> a little overboard. The electrical system has an 18.5 volt battery for >> starting, with no onboard charging, so energy consumption is a minor >> consideration. Tiny size, durability, and reliability are high priorities. >> >> Does anyone have an idea for a simpler design, or better yet, is >> someone already selling one? >> > My 1st thought is that the 'forgot' mode probably won't be effective (at > least for me), since it takes time for the heads to cool down. I know > I'd be likely to walk away before the light came on. > > 2nd thought is that since I'd want CHT gauges anyway, why not just use > them? I'd be sitting in the plane with the engine running, looking at > the instruments, so why not just look at the CHT? No power required, no > extra instrument. > > If you really want the light, an LM34 feeding a comparator circuit (op > amp and some resistors) would work. > > Charlie > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > ________________________________ Message 8 _____________________________________ Time: 09:58:20 AM PST US Subject: Re: AeroElectric-List: Simplest way for a go/no-go 2-Stroke Engine Temperature Indicator From: Charlie England Any temp sensor that you use will need to be in contact with the cyl, unless you want to use a laser thermometer. The TI doc describes soldering or gluing the LM34 to...whatever...., so you could use a metal case version, solder it to a bolt or pipe thread adapter that fits the CHT fitting in the head, and screw it in. http://www.ti.com/product/LM34/datasheet/layout#SNIS1613881 Just saw one possible limitation for the LM34; max operating temp is 300F. You might be able to work around that by mounting it on a fin, near the edge, instead of directly to the head. You'd need to 'calibrate' the temp delta between actual head temp & the temp at the edge of the fin, & set your trigger point based on that. On 1/2/2018 11:24 AM, Jared Yates wrote: > > > Thanks Charlie, this is a foot launch ultralight with no panel, so > pilot viewing space is especially premium. Does the LM34 need to be in > contact with the cylinder? I wonder how to best accomplish that, > mechanically speaking. > > > On January 2, 2018 11:37:25 Charlie England wrote: > >> >> >> On 1/2/2018 9:27 AM, Jared Yates wrote: >>> It's not good to initiate a takeoff with a 2-stroke engine that isn't >>> warm enough, so I'd like to find or make a circuit that measures the >>> temperature and extinguishes an LED when the temperature reaches a >>> certain threshold. Preferably I'd like to adjust that threshold with >>> software or a potentiometer. The result would be a "wait" light: start >>> the engine, and don't take off until the LED is out. That would also >>> function as a "you forgot to turn off the master" warning, after the >>> flying is done. >>> >>> My first thought was a type K thermocouple measuring CHT under the >>> spark plug, feeding to a hobbyist micro controller like this: >>> https://learn.adafruit.com/introducing-trinket >>> with a thermocouple amplifier like this: >>> https://www.adafruit.com/product/1778 >>> >>> But since I'm only wanting a simple and binary wait/go indication >>> rather than a readout in degrees, I wonder if the above plan is going >>> a little overboard. The electrical system has an 18.5 volt battery for >>> starting, with no onboard charging, so energy consumption is a minor >>> consideration. Tiny size, durability, and reliability are high >>> priorities. >>> >>> Does anyone have an idea for a simpler design, or better yet, is >>> someone already selling one? >>> >> My 1st thought is that the 'forgot' mode probably won't be effective (at >> least for me), since it takes time for the heads to cool down. I know >> I'd be likely to walk away before the light came on. >> >> 2nd thought is that since I'd want CHT gauges anyway, why not just use >> them? I'd be sitting in the plane with the engine running, looking at >> the instruments, so why not just look at the CHT? No power required, no >> extra instrument. >> >> If you really want the light, an LM34 feeding a comparator circuit (op >> amp and some resistors) would work. >> >> Charlie --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 9 _____________________________________ Time: 10:23:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Battery, Alternator, CB I'd agree with Joe. 'Traditionally', field breakers have been around 5 amps, but some regulators can try to draw more than that to get the alternator's output *voltage* up to the set point when there's a really heavy load on its output (like all the electrical stuff operating and suddenly hitting it with the load of a dead battery). The current draw of a regulator is no greater than the maximum current draw of the alternator field . . . which in turn is limited by its resistance. Few alternators of any size will exceed 4A of field current, most are in the 3A range. The alternator/regulator don't really control output *current*; they just try to maintain setpoint *voltage*.=C2 If a really big load is added, like pitot heat + landing lights + etc etc, plus a totally dead battery, then the alt/reg pair will try to supply whatever current is required to keep the voltage at the setpoint. (Ohm's Law). Only up to the alternator's inherent current limit which is set by the design of the alternator. Generators used to require independent output current limiting . . . they would willingly grunt a load far in excess of their ratings often resulting in burned armature wires and commutators. An alternator is inherently current limited. If you discover an alternator with burned stator wires and/or fused diodes, then yes . . . it was no doubt subjected to loads in the upper range of its ratings . . . BUT INADEQUATELY COOLED. As Joe said, 14.x volts applied to a fully charged battery will result in virtually no current flow into the battery. But the same 14.x volts applied to a nearly dead battery will likely result in close to full available current from the alternator into the battery. A lead-acid battery, fully charged, sitting at room temperature presents an open circuit terminal voltage of about 13.0 volts. Applying an external source at slightly above 13.0 will not charge the battery (i.e. convert the state of its chemistry) but it will SUPPORT any self discharge currents inherent in the physics of ANY lead-acid battery. This is what a maintainer does . . . got a couple 100a.h. batteries in the shop right now. One sitting on Battery a Tender showing a green light (charged), it measures 13.11 volts; the other sitting open circuit for the past week, it measures 12.88 volts. A deeply discharged battery floated on a 13.8v charger will eventually accumulate a charge at or near 100% of rated capacity . . . it might take weeks. For example, the two batteries cited above were purchased in July and installed in a friend's John Deere road grader . . . two 100a.h. batteries in series for 24v system. I became aware that the grader had not been used in several months. Went out to his ranch and absconded with both batteries. Just for grins, I put them both on Battery Tenders (0.75A charge rate). It took about a week for the BTs to show a green light . . . but they DID ultimately boost the batteries tot he 14.4 or so volts that causes the BT to transition from CHARGE to MAINTENANCE. Emacs! I am pleased to suggest that the little Battery Tender Jr. should not be discounted as a useful charge/maintenance tool for just about any size battery. Oh, yeah . . . the plot above was measured as an exemplar BT recharge profile . . . it was not taken on the batteries cited. The battery size vs alternator size 'waters' got muddied badly on another aviation forum by a certain lithium battery company telling its customers that they *did* have to limit alternator current capacity based on the lithium battery's capacity. That battery has a charge controller built in, so it shouldn't care about alternator size (just like a little 0.01 amp LED lamp doesn't care if it's hooked to a battery capable of 400 amps). Unfortunately, they've never been able to give a rational explanation for their rule. Pretty simple . . . not all lithium ion products are the same irrespective of their common chemistry. LiFePO4 is the chemistry of choice for robustness and generally 'airplane friendly' resistance to catching fire. However, the cell's ability to either sink or source high current values for extended periods of time is related to internal resistance (i.e. losses expressed as heating). There are LiFePO4 cells specifically tailored to accept and/or deliver large currents . . . an ESSENTIAL quality for miniature motive power (models, etc.) For example, this A123 product is speced to accept/deliver 30A https://tinyurl.com/yanszgtb This is approx 28 times the a.h. rating of the cell. This cell . . . https://tinyurl.com/y88ca38m while 'rated' at 9x the capacity of the A123 would toss in the towel at 10A of either charge/discharge. Most of the Lithium suppliers for light aircraft cranking batteries are using ROBUST cells. The direct answer to your question about too much charge current is that it shouldn't be dead in a flying airplane. :-) Seriously, the fact that it was allowed to go dead while in flight created a 'no good answer' situation, since an a/c charging system isn't designed to do a conditioned recharge of a dead battery. This goes to the core of the alternator vs. battery size discussion. When you crank an engine, the battery is generally tasked to the tune of about 5% of the contained energy. Yes, when the alternator comes on line, it will happily deliver whatever it can to meet the battery's acceptance rate which could be quite high . . . for a minute or so whereupon it begins to taper off. When operated in this 'normal' set of circumstances, even the smallest batteries are not damaged by what might otherwise appear to be an abusive recharge rate. However, allowing the ship's alternator to recharge a deeply discharged battery is another matter. This generally NEVER happens over the lifetime of the battery in your car . . . or your airplane. Most manuals for TC aircraft call for removing the deeply discharged battery from the airplane for bench recharge and inspection for airworthiness. The short answer: Select a lithium battery fabricated from robust cells. Be wary of "jump starting" the airplane and allowing the ship's alternator to stuff electrons back into a deeply discharged chemistry. If you can, go for the more sophisticated lithium products that emulate the features built into batteries qualified for TC aircraft . . . i.e. adequate, built in protection for over discharge, over charge, excessive current draw, etc. EarthX is one such product . . . there may be others by now. Haven't been tracking the market. ________________________________ Message 10 ____________________________________ Time: 10:27:18 AM PST US Subject: AeroElectric-List: Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind From: "user9253" Perhaps some kind of temperature switch would work? https://www.omega.com/pptst/TSW-TT.html -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477017#477017 ________________________________ Message 11 ____________________________________ Time: 01:35:54 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Battery, Alternator, CB On Tue, Jan 2, 2018 at 12:22 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > I'd agree with Joe. 'Traditionally', field breakers have been around 5 > amps, but some regulators can try to draw more than that to get the > alternator's output *voltage* up to the set point when there's a really > heavy load on its output (like all the electrical stuff operating and > suddenly hitting it with the load of a dead battery). > > The current draw of a regulator is no greater > than the maximum current draw of the alternator > field . . . which in turn is limited by its > resistance. Few alternators of any size will exceed > 4A of field current, most are in the 3A range. > > The alternator/regulator don't really control output *current*; they just > try to maintain setpoint *voltage*.=C3=82 If a really big load is added, like > pitot heat + landing lights + etc etc, plus a totally dead battery, then > the alt/reg pair will try to supply whatever current is required to keep > the voltage at the setpoint. (Ohm's Law). > > Only up to the alternator's inherent current limit > which is set by the design of the alternator. Generators > used to require independent output current limiting . . . > they would willingly grunt a load far in excess of > their ratings often resulting in burned armature > wires and commutators. > > An alternator is inherently current limited. If > you discover an alternator with burned stator > wires and/or fused diodes, then yes . . . it was > no doubt subjected to loads in the upper range > of its ratings . . . BUT INADEQUATELY COOLED. > > As Joe said, 14.x volts applied to a fully charged battery will result in > virtually no current flow into the battery. But the same 14.x volts appli ed > to a nearly dead battery will likely result in close to full available > current from the alternator into the battery. > > A lead-acid battery, fully charged, sitting at room > temperature presents an open circuit terminal > voltage of about 13.0 volts. Applying an external > source at slightly above 13.0 will not charge the > battery (i.e. convert the state of its chemistry) > but it will SUPPORT any self discharge currents > inherent in the physics of ANY lead-acid battery. > > This is what a maintainer does . . . got a couple 100a.h. > batteries in the shop right now. One sitting on Battery a > Tender showing a green light (charged), it measures > 13.11 volts; the other sitting open circuit for the past > week, it measures 12.88 volts. > > A deeply discharged battery floated on a 13.8v charger > will eventually accumulate a charge at or near 100% of > rated capacity . . . it might take weeks. For example, > the two batteries cited above were purchased in July > and installed in a friend's John Deere road grader . . . > two 100a.h. batteries in series for 24v system. > > I became aware that the grader had not been used in > several months. Went out to his ranch and absconded with > both batteries. Just for grins, I put them both on Battery > Tenders (0.75A charge rate). It took about a week > for the BTs to show a green light . . . but they DID > ultimately boost the batteries tot he 14.4 or so > volts that causes the BT to transition from CHARGE > to MAINTENANCE. > > [image: Emacs!] > > I am pleased to suggest that the little Battery Tender Jr. should > not be discounted as a useful charge/maintenance tool for just > about any size battery. Oh, yeah . . . the plot above was measured > as an exemplar BT recharge profile . . . it was not taken on the > batteries cited. > > The battery size vs alternator size 'waters' got muddied badly on another > aviation forum by a certain lithium battery company telling its customers > that they *did* have to limit alternator current capacity based on the > lithium battery's capacity. That battery has a charge controller built in , > so it shouldn't care about alternator size (just like a little 0.01 amp L ED > lamp doesn't care if it's hooked to a battery capable of 400 amps). > Unfortunately, they've never been able to give a rational explanation for > their rule. > > Pretty simple . . . not all lithium ion products are the same > irrespective of their common chemistry. LiFePO4 is the chemistry > of choice for robustness and generally 'airplane friendly' resistance > to catching fire. However, the cell's ability to either sink or source > high current values for extended periods of time is related to > internal resistance (i.e. losses expressed as heating). > > There are LiFePO4 cells specifically tailored to accept and/or > deliver large currents . . . an ESSENTIAL quality for miniature > motive power (models, etc.) For example, this A123 product is > speced to accept/deliver 30A > > https://tinyurl.com/yanszgtb > > This is approx 28 times the a.h. rating of the cell. This > cell . . . > > https://tinyurl.com/y88ca38m > > while 'rated' at 9x the capacity of the A123 would toss in the towel at > 10A of either charge/discharge. Most of the Lithium suppliers > for light aircraft cranking batteries are using ROBUST cells. > > The direct answer to your question about too much charge current is that > it shouldn't be dead in a flying airplane. :-) Seriously, the fact that i t > was allowed to go dead while in flight created a 'no good answer' > situation, since an a/c charging system isn't designed to do a conditione d > recharge of a dead battery. > > This goes to the core of the alternator vs. battery size > discussion. When you crank an engine, the battery is generally > tasked to the tune of about 5% of the contained energy. Yes, > when the alternator comes on line, it will happily deliver > whatever it can to meet the battery's acceptance rate which > could be quite high . . . for a minute or so whereupon it begins > to taper off. When operated in this 'normal' set of circumstances, > even the smallest batteries are not damaged by what might otherwise > appear to be an abusive recharge rate. > > However, allowing the ship's alternator to recharge a deeply > discharged battery is another matter. This generally NEVER happens > over the lifetime of the battery in your car . . . or your airplane. > Most manuals for TC aircraft call for removing the deeply discharged > battery from the airplane for bench recharge and inspection > for airworthiness. > > The short answer: Select a lithium battery fabricated from > robust cells. Be wary of "jump starting" the airplane and allowing > the ship's alternator to stuff electrons back into a deeply > discharged chemistry. If you can, go for the more sophisticated > lithium products that emulate the features built into batteries > qualified for TC aircraft . . . i.e. adequate, built in protection > for over discharge, over charge, excessive current draw, etc. > > EarthX is one such product . . . there may be others by now. Haven't > been tracking the market. > When I said 'try', that's what I meant; that it would *try* to supply whatever it *could* to keep the voltage at setpoint. The OP did say that his *field* breaker tripped. There have been several cases reported on various forums of 5A field breakers popping under high alternator output loads, and IIRC, someone actually posted on one of the forums (don't recall if it was here or elsewhere) at least one alternator spec sheet showing its field current could run very close to, or even above, 5A. I've never experienced the problem, but apparently others have, on multiple occasions. The mfgr I referenced that was muddying the waters on battery cap vs alternator cap is, in fact, EarthX. I've swapped posts with their public face on the VAF forum several times, and it would seem that even if they have a perfect product, their marketing face has no idea how it works. Scroll to the chart near the bottom of this page: earthx Charlie ________________________________ Message 12 ____________________________________ Time: 01:56:51 PM PST US Subject: AeroElectric-List: Re: Battery, Alternator, CB From: "Eric Page" nuckolls.bob(at)aeroelect wrote: > This cell... > > https://tinyurl.com/y88ca38m (https://tinyurl.com/y88ca38m) > > while 'rated' at 9x the capacity of the A123 would toss in the towel at 10A of either charge/discharge. Most of the Lithium suppliers for light aircraft cranking batteries are using ROBUST cells. I just want to point out, hopefully before anyone orders them, that these cells are most assuredly fakes. It's a symptom of a common problem with electronic components and "modules" from Chinese sellers; they frequently, and sometimes grossly, exaggerate the ratings or capabilities of their products. "High capacity" 18650s like these always test very poorly, often under 1,000maH. The highest legitimate capacity rating for an 18650 Li-Ion cell at present is the Panasonic NCR18650G at 3,600maH, but those are exceedingly hard to find in the wild. The highest capacity cells that are readily available are the LG MJ1 at 3,500mAh (rated 10A discharge) and the Panasonic NCR18650B at 3,400maH (rated 4.875A discharge). Generally speaking there's an inverse relationship between cell capacity and maximum discharge rate, though the MJ1 is challenging this notion. If you need 18650 cells for a project, you should stick to Panasonic, Sanyo, LG, Samsung, Sony or A123. Many of the other names-you've-never-heard-of brands use cell manufacturer and battery pack producer rejects, or used/salvaged cells (from laptop and tool batteries, typically). Some of these are stripped and re-wrapped to look like genuine high-spec OEM cells. Some sellers will even rewrap genuine cells of lower capacity (and cost) to look like high-spec cells. About 18 months ago there was a shortage of Samsung HG2 cells (3,000mAh, 20A discharge) when the factory shut down for retooling, and Chinese counterfeiters quickly began rewrapping HE2 cells (2,500maH, 20A discharge) as HG2s. Since the HE2 costs about $1 less in bulk and looks identical except for wrapping color, it was an easy moneymaker. Finding a seller with genuine name-brand cells can be a challenge on eBay, and the problem isn't limited to Chinese sellers since they wholesale their fakes to resellers around the globe. Be careful out there... Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477023#477023 ________________________________ Message 13 ____________________________________ Time: 01:57:17 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Product Alert A venerable digital multimeter from my Beech "GoBox" finally went belly up after 10-12 years. Ordered this item for replacement: https://goo.gl/TSJsij This turns out to be an amazing value for accuracy and utility. Its an auto-ranging multimeter that measures ac/dc volts rms, millivolts rms, ohms, frequency to 10Khz, ac/dc amps and microamps and is even an signal generator. I've not checked the accuracy extensively . . . but the parameters I did look at tracked nicely with readings from the bench Fluke and Tektronix instruments. Better yet, it's about 1/4th the volume and weight of the instrument it's replacing . . .t he toolbox was getting tight. The banana jacke are actually on 0.75" centers! Will report new discoveries when and if they arise . . . Bob . . . ________________________________ Message 14 ____________________________________ Time: 02:16:21 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Battery, Alternator, CB > >The OP did say that his *field* breaker tripped. >There have been several cases reported on >various forums of 5A field breakers popping >under high alternator output loads, and IIRC, >someone actually posted on one of the forums >(don't recall if it was here or elsewhere) at >least one alternator spec sheet showing its >field current could run very close to, or even >above, 5A. I've never experienced the problem, >but apparently others have, on multiple occasions.=C2 Hmmmm . . . I'd like to know which brand/model of alternator has so high a power requirement. Recall that an alternator's output is de-rated by what ever current is required to excite the field. I.e. a 60A ND alternator is 'really' ginning out 63A at minimum speed for full output. This is the condition where the regulator is full-ON and field voltage is equal to bus voltage. 5A of field current would dump 5 x 14 = 70 watts of no-value-added heat into the alternator's interior or about 10% of total energy. When a field breaker opens in flight, the first thought questions whether or not the system is fitted with crowbar ov protection . . . and they have suffered a nuisance trip. Another question explores the possibility of a shorted field winding where apparent field resistance goes down and potential field current goes up to compensate for the 'lost turns'. I've got a situation like that right now in my Minivan. A/C was popping clutch fuse . . . every so often. Measurement of current through the 7A fuse showed that clutch current was about 9A. Fewer turns of wire . . . but higher current . . . and the a/c continued to function if I put a 10A fuse in the holder. Ordered a new compressor/clutch assembly and put it on the shelf in anticipation of needing to replace it soon. The system ran though the rest of the summer . . . so I don't have to go turn any wrenches until spring. I have no foundation from which to argue with anyone's observations . . . but if they were suffering nuisance trips of a 5A breaker on an alternator field, I think it VERY likely that the 5+ amp draw is not related to the field current requirements of a normally functioning alternator. Bob . . . ________________________________ Message 15 ____________________________________ Time: 02:30:42 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Battery, Alternator, CB On Tue, Jan 2, 2018 at 4:15 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > > The OP did say that his *field* breaker tripped. There have been several > cases reported on various forums of 5A field breakers popping under high > alternator output loads, and IIRC, someone actually posted on one of the > forums (don't recall if it was here or elsewhere) at least one alternator > spec sheet showing its field current could run very close to, or even > above, 5A. I've never experienced the problem, but apparently others have , > on multiple occasions.=C3=82 > > > Hmmmm . . . I'd like to know which brand/model of alternator > has so high a power requirement. Recall that an alternator's > output is de-rated by what ever current is required to excite > the field. I.e. a 60A ND alternator is 'really' ginning out > 63A at minimum speed for full output. This is the condition > where the regulator is full-ON and field voltage is equal > to bus voltage. > > 5A of field current would dump 5 x 14 = 70 watts > of no-value-added heat into the alternator's interior > or about 10% of total energy. > > When a field breaker opens in flight, the first thought > questions whether or not the system is fitted with crowbar > ov protection . . . and they have suffered a nuisance trip. > Another question explores the possibility of a shorted > field winding where apparent field resistance goes down > and potential field current goes up to compensate for the > 'lost turns'. > > I've got a situation like that right now in my Minivan. > A/C was popping clutch fuse . . . every so often. Measurement > of current through the 7A fuse showed that clutch current > was about 9A. Fewer turns of wire . . . but higher current . . . > and the a/c continued to function if I put a 10A fuse in > the holder. > > Ordered a new compressor/clutch assembly and put it on > the shelf in anticipation of needing to replace it soon. > The system ran though the rest of the summer . . . so > I don't have to go turn any wrenches until spring. > > I have no foundation from which to argue with anyone's > observations . . . but if they were suffering nuisance > trips of a 5A breaker on an alternator field, I think it > VERY likely that the 5+ amp draw is not related to > the field current requirements of a normally functioning > alternator. > > Bob . . . > That could well be the case. There are a lot of 'alternative facts' on the interwebs these days.... ________________________________ Message 16 ____________________________________ Time: 02:36:59 PM PST US Subject: AeroElectric-List: Re: Product Alert From: "Eric Page" Indeed, these are nice little units and I agree, they're an amazing value. I bought the AN8009 recently, which is identical to your AN8008 except that it replaces the signal generator feature with temperature measurement and comes with a Type-K thermocouple. Mine appears to be quite accurate and is easy to use. My only complaint is a minor one: the LCD display could be a bit better on-axis; it's easiest to read if the meter lays flat on the bench and is viewed at a low angle from below the meter. Otherwise, at Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477027#477027 ________________________________ Message 17 ____________________________________ Time: 06:34:56 PM PST US Subject: Re: AeroElectric-List: Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind From: Charlie England On 1/2/2018 12:26 PM, user9253 wrote: > > Perhaps some kind of temperature switch would work? > https://www.omega.com/pptst/TSW-TT.html > > -------- > Joe Gores > I like Joe's find. Still have to watch the max temp, though. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 18 ____________________________________ Time: 07:18:36 PM PST US From: Jared Yates Subject: Re: AeroElectric-List: Re: Simplest way for a go/no-go 2-Stroke Engine Temperature Ind I like the temperature switch very much, thanks! Now I just need a little trial and error to sort out the right temperature range. On Tue, Jan 2, 2018 at 9:39 PM, Charlie England wrote: > ceengland7@gmail.com> > > On 1/2/2018 12:26 PM, user9253 wrote: > >> >> Perhaps some kind of temperature switch would work? >> https://www.omega.com/pptst/TSW-TT.html >> >> -------- >> Joe Gores >> >> I like Joe's find. Still have to watch the max temp, though. > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.