Question about the backup battery.

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Rich
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Re: Question about the backup battery.

Post by Rich »

CFIDave wrote: Mon Mar 29, 2021 12:38 am
shoulderdoc wrote: Mon Mar 29, 2021 12:25 amI voltage tested it, and it was fine, after 14 years!
Yes, but I doubt it would have lasted very long with a load on it (not just testing with a voltmeter). After 14 years the battery probably wouldn't have been able to supply enough watt-hours of power to drive the backup AI and lighting for 30+ minutes.
This is true. I have lots of examples of Li-Ion batteries that lost their oomph well short of the 14 years. It showed up in duration (or lack thereof) in my laptops, phones, GPSs and so on. Somewhere around 6 years it was really noticeable how quickly they would run down.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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gsontheimer
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Re: Question about the backup battery.

Post by gsontheimer »

Laptops, phones, etc. contain a rechargeable lithium-ion battery. They typically have a life time of 300-500 charge cycles or 3 years. The latest modely may outlast 1.000 cycles but no more than 3 years. The lithium batteries in the DA40 come with an expiration date (shelf life) of 10 years printed on them. After 14 years they will not have the full capacity, but probably more than 50%, although this is no longer guaranteed. But we must throw them away after 2 years anyway. Probably because Diamond forgot to change this requirement when they replaced the battery pack with the lithium battery.
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Re: Question about the backup battery.

Post by Rich »

Upon further review (midnight epiphany, really), the Lithium packs are primary LiMn batteries not Li-Ion secondaries as used in cell phones, etc. These should have shelf life of 10+ years but once used are discarded.

Having said that, the alkaline Duracells in my battery pack also have a shelf life of 10 years but also must be replaced on the same schedule.

But I've also had both alkaline and Lithium primary batteries leak/fail after only a few years - unused.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rick
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Re: Question about the backup battery.

Post by Rick »

The emergency battery pack from my 2004 DA40 contained 12 Panasonic CR123A Lithium Metal 3v batteries, just like these. I haven't opened the battery pack from my 2007 yet, but it is a different shape, so probably different cells inside. I still believe the 2-year replacement requirement for the emergency battery pack is left over from the original setup where there was a plastic tray of (24?) AA batteries that were to be replaced every two years. I only wish they had made a tray for the Lithium cells so we could just replace them instead of ordering the entire custom-made very-expensive shrink-wrapped pack directly from Diamond...
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Re: Question about the backup battery.

Post by CFIDave »

Rick wrote: Tue Mar 30, 2021 2:07 pmI only wish they had made a tray for the Lithium cells so we could just replace them instead of ordering the entire custom-made very-expensive shrink-wrapped pack directly from Diamond...
And that have to be shipped via ground because they're obviously too dangerous to ship in an aircraft! :roll:
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Rich
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Re: Question about the backup battery.

Post by Rich »

CFIDave wrote: Tue Mar 30, 2021 2:10 pm
Rick wrote: Tue Mar 30, 2021 2:07 pmI only wish they had made a tray for the Lithium cells so we could just replace them instead of ordering the entire custom-made very-expensive shrink-wrapped pack directly from Diamond...
And that have to be shipped via ground because they're obviously too dangerous to ship in an aircraft! :roll:
Correct. Replacing the original ones isn't much of a hardship and essentially zero cost. In fact, I don't see why a change from the original design was required. Basically the batteries power the same devices when activated.

Mine is now set up to only power the floodlight and has near zero chance of ever being truly needed.
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Re: Question about the backup battery.

Post by Rick »

It doesn't seem like it would be too difficult to 3d-print a plastic case to hold the correct number of off-the-shelf lithium cells to replace the current emergency battery pack. I wonder why Diamond hasn't done this already - it seems like that would be much easier than custom-building the individual packs.
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Re: Question about the backup battery.

Post by gsontheimer »

Maybe $$$$$ ?
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Re: Question about the backup battery.

Post by Rich »

This weekend I'll undertake the biennial rotation of 28 perfectly usable AA batteries into my stash to feed various other gizmos and replace them with 28 more such batteries. Rinse and repeat in 2024 :D

These now feed only my floodlight, should I experience an electrical system failure at night, need to see things not already self-illuminated and decide not to use my iPad to light the panel instead.

It's really zero expense to do this, and it only takes an hour or so to accomplish, but it does seem a futile exercise. :scratch:
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Re: Question about the backup battery.

Post by Steve »

Rich:

Same here, the emergency battery on mine now powers only the floodlight, the AI having its own backup (which I tested by pulling the breaker on a recent flight - it still had 35% after 90 minutes). I also use the exchanged Duracells for flashlights and other devices (my Zaon TPAS uses two, my D/C ancient noise cancelling headset uses another 4). I do like switching them out, since I have seen Duracell AA batteries leak after 2 or 3 years. I always do mine coincident with an Annual Inspection, since the IP cover is already off for that anyway.
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