flyingchump Posted March 13, 2021 Report Share Posted March 13, 2021 I'm sure someone has done this before... Thought some of the curious among us might want to see. I just replaced my 1010 ELT battery during the annual so I thought I'd take apart the old one. I've heard they are just D batteries but I want to see how they were configured. I know I shouldn't have been, but I was surprised at just how simple it was... 9 D cell Rayovac High Energy batteries welded in series (1P9S) wrapped in masking tape and hot snotted in a case... Super easy and cheap to build. The battery was only $35 from spruce so I'm not complaining. The pack expires next month (April 2021) and measured 14.56 volts. 9 batteries rated at 1.5volts each only calculates to 13.5. So my battery was measuring a full volt higher than rated. Not bad but not measured under load. The batteries had Feb 2028 printed on them with is a almost 7 years past the replacement date of the pack (4/21)... Seems excessive to replace every 2 years but I'm sure someone had a reason for this 30+ years ago. Quote Link to comment Share on other sites More sharing options...
takair Posted March 13, 2021 Report Share Posted March 13, 2021 I use the old ones in our basement CO detectors, sitting on a shelf.... they last forever for that application and the detector will beep at you when they go bad. Makes me feel like I’m really getting my money out of them. 3 Quote Link to comment Share on other sites More sharing options...
GeeBee Posted March 13, 2021 Report Share Posted March 13, 2021 I found this interesting 2 Quote Link to comment Share on other sites More sharing options...
MooneyMitch Posted March 13, 2021 Report Share Posted March 13, 2021 Always enjoy Paul’s logic mixed in with his sarcastic humor!! He is, undoubtedly, our National general aviation CB’s club president!! Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 13, 2021 Report Share Posted March 13, 2021 Alkaline batteries, though nominally rated at 1.5V, have an open circuit voltage of about 1.55 to 1.65V. The open circuit voltage is a measure of charge state but not capacity which must be tested under load. Batteries produce current by converting the energy released by chemical reactions into electrical energy. These chemical reactions take place to some extent even when the battery is not supplying current to a load. This is called self discharge and affects what is commonly referred to as shelf life. (Someone once noted that a flashlight is a tubular container for storing dead batteries ). The chemical reactions are heat sensitive -- batteries run down faster in hot temperatures. Most alkaline batteries have a shelf life at room temperature of about 5 years. FAR 91.207 requires ELT battery replacement at 50% of useful life. So taking 5 years, adjusting for elevated storage temperature in an airplane sitting on the ramp at Phoenix, and dividing by two yields about 2 years. It's probably overly conservative, but this is a last resort safety device and the batteries are relatively inexpensive. Lithium batteries used in newer 406MHz ELTs have a longer life -- I just replaced the one in my ACK and it has a life of 5 years. id_alkaline_1203_e.pdf Skip 1 Quote Link to comment Share on other sites More sharing options...
A64Pilot Posted March 13, 2021 Report Share Posted March 13, 2021 You don’t replace them when they are dead, the replacement interval is based on being able to guarantee X number of operating hours in a cold environment. 121.5 / 243.0 ELT’s are worthless as those frequencies aren’t even monitored anymore by rescue coordination centers. 406 on the other hand, works and works well. Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted March 13, 2021 Report Share Posted March 13, 2021 IIRC when I ordered my 121.5 replacement battery, it had a replace date that was about 2 years and 3 months away, so the true CB would order it just before it was due Quote Link to comment Share on other sites More sharing options...
EricJ Posted March 13, 2021 Report Share Posted March 13, 2021 An alternative interpretation is that ~30% more crashes were located with ELTs than may have been located without them. There are a lot of screening or testing processes that look bad in percent success rates, but look really good in improvement compared to not doing them. 1 Quote Link to comment Share on other sites More sharing options...
GeeBee Posted March 13, 2021 Report Share Posted March 13, 2021 30% crashes they work, but nothing to say if they did work, that the crash would not have been located anyway. As mentioned, the CAP and search authorities now use ADS-B and cell phone data more than ELT data. In addition newer and more reliable technology exists. The fact is, the legal requirements have not kept pace with the technology and we are saddled with a beacon of dubious reliability in the event it is needed. Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 13, 2021 Report Share Posted March 13, 2021 Modern-ish ELTs... Have a panel mounted switch for them... This allows the PIC to broadcast his position prior to the accident removing the antenna and breaking the switch... -a- 2 Quote Link to comment Share on other sites More sharing options...
A64Pilot Posted March 14, 2021 Report Share Posted March 14, 2021 4 hours ago, GeeBee said: 30% crashes they work, but nothing to say if they did work, that the crash would not have been located anyway. As mentioned, the CAP and search authorities now use ADS-B and cell phone data more than ELT data. In addition newer and more reliable technology exists. The fact is, the legal requirements have not kept pace with the technology and we are saddled with a beacon of dubious reliability in the event it is needed. I’d say your correct for 121.5 ELT, but not the 406. the 406 sends a signal to the RCC that says the tail number to the airplane is down and gives an exact location if it’s a better one, the old ones didn’t give a position and it took a few satellite passes to determine position. ‘But a 406 is registered, so if your 406 ELT goes off, the first thing they do is call the telephone number on the registration, if someone answers and say yes he’s out flying then they get serious. FAA never wanted ELT’s Congress mandated them after a Congressman went missing in Alaska and wasn’t found. Just trivia. https://www.aopa.org/advocacy/aircraft/aircraft-operations/emergency-locator-transmitters Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 14, 2021 Report Share Posted March 14, 2021 I've done a lot of flying in Alaska, Canada and the western US where I'm currently based. I've got a 406 MHz ELT connected to the GPS, a cell phone, a EPIRB and a handheld VHF comm radio. I have often thought of adding a satellite phone. If I go down, and survive, I want lots of signals pointing to my location! When I flew out of Ketchikan we flew over snow (white) mountains (brown) and forest (green). This is the paint scheme the company chose for our airplanes: Quote Link to comment Share on other sites More sharing options...
GeeBee Posted March 14, 2021 Report Share Posted March 14, 2021 I think you need to watch the video. I say that to you only because the Hale Boggs incident was covered. Yes, transmission of position is better, but as the author points out, a lot of ELT do not survive impact making them useless regardless of type. That rate is 50%. IOW, 50% of crashes, the ELT fails to activate. That is not what I would call a good or reliable record. In only 18% could the ELT be definitive in finding the crash site. Look, I was a big believer in the GPS equipped 406 ELT and when I bought my Ovation, I spent big money getting the best unit possible. The more I see of ELT failure and the fact that other methods are becoming primary in locating downed aircraft, the more I believe I wasted my money. Quote Link to comment Share on other sites More sharing options...
ZuluZulu Posted March 14, 2021 Report Share Posted March 14, 2021 My 121.5MHz ELT failed inspection due to “cracks in the case” so I opted to replace it with a 406MHz ELT. The only downside has been that the difficulty in connecting it to the integrated antenna foreward of the vertical stabilizer would have added significant labor costs and introduce risks of unintended consequences, so we installed the whip antenna that came with it from Artex. I have to say — I HATE the aesthetics of the whip antenna. Every time I look at it I cringe. But at least they’ll be able to find me if I wreck! *knock on wood* Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted March 14, 2021 Report Share Posted March 14, 2021 Don’t bother with the gps integration. Our local shop did a test with the Air Force and without the gps they pin pointed the Elt to within 200 feet of their door to their shop. At that point they stopped bothering with gps integration. 1 Quote Link to comment Share on other sites More sharing options...
A64Pilot Posted March 15, 2021 Report Share Posted March 15, 2021 19 hours ago, RobertGary1 said: Don’t bother with the gps integration. Our local shop did a test with the Air Force and without the gps they pin pointed the Elt to within 200 feet of their door to their shop. At that point they stopped bothering with gps integration. Without a GPS signal the position is triangulated by satellite passes, so yes they can accurately triangulate you,but it takes time to get several passes, depends on if your willing to wait a day or so. A good ELT has a built in GPS, ref the EPIRB mentioned above, that’s a boat thing, stands for Emergency Position Indicating Radio Beacon. and an EPIRB for sending out an emergency signal is as good as it gets, but it won’t be automatically activated in a crash. ‘When I ferried aircraft to Central and South America I carried a Sat phone and a PLB, a PLB is pretty much an EPIRB, except it doesn’t float or auto activate in water, and has a shorter battery transmit time. Aircraft I was ferrying didn’t have ELT’s The Garmin Inreach and Spot etc advertise them as rescue devices, but they do not transmit to the RCC, the Air Force Rescue Coordination Center, for those you have to hope the person in the call center or whoever gets the emergency message gets it right. Probably more than you ever wanted to know about EPIRB’s PLB, and ELT’s https://www.sarsat.noaa.gov/faq 2.html 1 Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted March 15, 2021 Report Share Posted March 15, 2021 12 minutes ago, A64Pilot said: Without a GPS signal the position is triangulated by satellite passes, so yes they can accurately triangulate you,but it takes time to get several passes, depends on if your willing to wait a day or so. A good ELT has a built in GPS, ref the EPIRB mentioned above, that’s a boat thing, stands for Emergency Position Indicating Radio Beacon. and an EPIRB for sending out an emergency signal is as good as it gets, but it won’t be automatically activated in a crash. ‘When I ferried aircraft to Central and South America I carried a Sat phone and a PLB, a PLB is pretty much an EPIRB, except it doesn’t float or auto activate in water, and has a shorter battery transmit time. Aircraft I was ferrying didn’t have ELT’s The Garmin Inreach and Spot etc advertise them as rescue devices, but they do not transmit to the RCC, the Air Force Rescue Coordination Center, for those you have to hope the person in the call center or whoever gets the emergency message gets it right. Probably more than you ever wanted to know about EPIRB’s PLB, and ELT’s https://www.sarsat.noaa.gov/faq 2.html I don’t think you’re going to find integrated gps in your standard $500 406 elt. I think you’re better off spending your safety dollars elsewhere as I said the gps adds little Quote Link to comment Share on other sites More sharing options...
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