Lithium Backup Battery Pack

[Lance Murray]

I believe the difference may be with the shipping company. UPS will not take the batteries unless they are declared. We have had two airplanes destroyed due to lithium batteries. Fedex has lost more than one also.

[

Good question, Gary. The guys in this forum thread don't seem to have a mail-order or shipping problem with CR-123A cells into or within Canada.

Slowly but surely I get the idea that the Diamond Aircraft pricing is a bit like the printer cartridge business: get the printer for 39,99$ and if you need a replacment cartridge, you have to pay nearly the same.

But hazardous shipping does not help Diamond so why do they use it if it is not required?

[Lance Murray]

This discussion makes me think about the FAA allowance for "Owner Produced Parts". Maybe it is time to think about this again.

http://150cessna.tripod.com/parts.html

If someone would be able to send me an expired pack I can start finding an alternative method of compliance. I am nearly certain that Diamond won't send the specs and drawings but this can't be hard to reverse engineer. They are off the shelf Panasonic CR123A cells and likely a charging and protection circuit. Shouldn't be too tough unless the circuits are proprietary. Someone could even produce a kit with the paperwork for final assembly to be accomplished by the owner. The owner could obtain the cells locally to avoid the HAZMAT charge.

[Kai]

Following up on my post regarding the Li battery replacement, let me now make clear that the problem is with Diamond. The director of maintenance at the FBO has been on the phone with three different departments up there and has been stonewalled; there has been no offer of compromise, and now they're saying "send us a photo of the date on the battery so we can confirm what you allege"--like maybe nobody here can read. Of course the battery is already in the plane, so if we do what they want the glareshield has to come back off and probably the battery removed to get a picture. One of the silly things about this is that when the FBO first tried to order the battery (when the annual was scheduled) they were told batteries were backordered, and in fact took over a month to arrive. One would think, then, that newly stocked batteries would be fresh, no?

Very annoying. Very, very annoying. Even if they would now change their opinion and replace the batteries, it still shows Diamond Aircraft Industries in a bad light.

[Rick]

This discussion makes me think about the FAA allowance for "Owner Produced Parts". Maybe it is time to think about this again.

http://150cessna.tripod.com/parts.html

If someone would be able to send me an expired pack I can start finding an alternative method of compliance. I am nearly certain that Diamond won't send the specs and drawings but this can't be hard to reverse engineer. They are off the shelf Panasonic CR123A cells and likely a charging and protection circuit. Shouldn't be too tough unless the circuits are proprietary. Someone could even produce a kit with the paperwork for final assembly to be accomplished by the owner. The owner could obtain the cells locally to avoid the HAZMAT charge.

Lance, I can send you my old pack. I don't believe there is any circuit involved, though - simply 8 CR123A cells strung together in series with a wire attached to each end. According to the wiring diagram, this battery pack is not connected to the electrical system at all, so it is never charged. It just sits there until you flip the Emergency switch. I opened it up a bit when I removed it a couple of years ago, but not completely. I will investigate more when I get home tonight and report back.

[Lance Murray]

Oh yes, I forgot that it doesn't charge. There should be some sort of low voltage cutoff circuit to not drain the batteries below the safe voltage. Protected CR123A's do have internal protection and venting to prevent explosion. Not sure if that would be enough though. From what I understand the danger in using cr123s is when using multiple batteries together in series.

This discussion makes me think about the FAA allowance for "Owner Produced Parts". Maybe it is time to think about this again.

http://150cessna.tripod.com/parts.html

If someone would be able to send me an expired pack I can start finding an alternative method of compliance. I am nearly certain that Diamond won't send the specs and drawings but this can't be hard to reverse engineer. They are off the shelf Panasonic CR123A cells and likely a charging and protection circuit. Shouldn't be too tough unless the circuits are proprietary. Someone could even produce a kit with the paperwork for final assembly to be accomplished by the owner. The owner could obtain the cells locally to avoid the HAZMAT charge.

Lance, I can send you my old pack. I don't believe there is any circuit involved, though - simply 8 CR123A cells strung together in series with a wire attached to each end. According to the wiring diagram, this battery pack is not connected to the electrical system at all, so it is never charged. It just sits there until you flip the Emergency switch. I opened it up a bit when I removed it a couple of years ago, but not completely. I will investigate more when I get home tonight and report back.

[Lance Murray]

We can use these batteries in a survival situation. Start a fire or use as a signal flare. Diamond thinks of everything.

I opened the pack.
It's made of PANASONIC CR-123-A cells.

LOL. We have a bomb in our planes which can be conveniently brought to explosion with a simple vice...

[Rick]

So tonight I tore into the battery pack I removed from my first DA40 several years ago. Here is the top of the pack before dissection (interesting - the "expiry date" was crossed out when we removed the pack)

Top of battery pack -

DSC01586a.jpg (487.32 KiB) Viewed 3438 times

Here is the bottom of the pack, showing the Diamond part number sticker

Bottom of battery pack -

DSC01587a.jpg (475.14 KiB) Viewed 3438 times

And here are the individual cells, after removing the outer wrapper which holds the pack to the metal plate, and then the middle wrapper which holds the 6 packs of 2 cells each together, and then cutting into the inner wrapped which holds the pair of cells together:

Individual battery cells -

DSC01593a.jpg (408.26 KiB) Viewed 3438 times

There is no circuit of any kind. The 12 cells (yes, 12) are simply wired in series, giving 36 volts. Each pair of cells has a bent piece of metal soldered between them, and then the alternating ends are also soldered together, as you might expect. By the way, I measured the voltage on my now-at-least-6-year-old battery pack at 39.1 volts with no load.

It seems like the logical thing to do would be to design a holder for the 12 cells that allows for just the individual cells to be replaced every 2 years, like we do with the ELT and the older DA40's that took a bunch of D-cell batteries...

We can use these batteries in a survival situation. Start a fire or use as a signal flare. Diamond thinks of everything.

Lance, you really cracked me up!

[Lance Murray]

Seems to me that this would be very simple to "owner produce" these packs.

I agree with the replaceable battery holder concept however this would require at a minimum a form 337 field approval. I have been told that FSDO's have been reluctant to do anything in regards to field approvals though.

It also looks like this two year cycle is designed to increase profits at Diamond. If a pack has an expiry date ten years after assembly then why the replacement? Shouldn't a voltage test suffice?

Maybe as a group we can petition the FAA for an AMOC. Remove, test for minimum voltage, inspect for physical damage, re-install or replace at a time period near the expiry date.

[Steve]

There may be some hope for increasing the replacement interval. The DPU memory battery in the VM-1000 originally had a two year replacement interval specified by Diamond, despite an eight year interval being specified by Vision Microsystems. Interestingly, the battery manufacturer guarantees > 20 years at 60 degrees C! After a few years, Diamond adopted the eight year interval.

So, I'm on my third memory battery now, the first being replaced at two years, the second at ten years. I never tested these lithium cells, but I never had an issue with them operationally. Next due...

...2019.

Steve

[Eric N]

Somewhat sheepish update on my "nearly outdated" battery pack: today we opened the glareshield and, behold, the actual expiration date is 2022, not 2013! The avionics chief is embarrassed--says he can't understand how he could have read it that way--and I get a new logbook stickie saying the pack doesn't have to be replaced until 2014, and Diamond is off the hook. I plan to ask for the pack when it is removed in 2 years; the tech says it can't be legally reinstalled but I wonder if we all couldn't have a "battery exchange" and just pass around our recently removed but not expired lithium packs.