Lithium Backup Battery Pack

[Kurt h]

Our plane is due for the 2 year replacement of the backup lithium battery pack. I went through Don Davis Aviation last time for $186 + $95 hazardous shipping charge. Has anyone found a less expensive way to acquire this battery pack?

[Lance Murray]

I hoped someone had this answer too. My battery is also due for replacement.

[Rick]

I am holding in my hand the emergency battery pack I removed 2 years ago. I ran all the part numbers on it, and also looked for something comparable online, but no luck so far. It's a 36-volt 1300mAh Lithium battery pack. Diamond's part number is D41-2560-93-00. This unit also has the following other part numbers on it: 2EXL1240 and 04-156-2336. It appears to be 6 6v Li cells wired in series, wrapped in plastic, with a metal plate attached to the bottom for mounting.

My old pack still tests at 38v with no load.

[Jean]

Is this battery backup pack something the owner/operator can replace himself or does it need to be executed by the avionics shop?

[Rick]

Jean,

It's easy to replace yourself, and my take on it is that you don't need a signoff. Part 41, Appendix A, paragraph C lists the 32 preventive maintenance items a private pilot can do him(her)self, and item 24 is:

(Part 41, Appendix A)
(c) Preventive maintenance. Preventive maintenance is limited to the following work, provided it does not involve complex assembly operations:
:
(24) Replacing and servicing batteries.
:

You need to make a logbook entry for it and sign it yourself.

[Steve]

One wonders if "replacinmg and servicing" could be legally interpreted to be: removing the cells from the backing plate, purchasing some new 6 volt lithium cells from Newark, etc., soldering the leads together, and mounting them on the plate?

I'm glad my emergency battery is 28 AA Duracells...

Steve

[Rick]

So all the questions prompted me to further disassemble my old battery pack. It turns out the "six" cells are actually 12 cells, heavily shrink-wrapped in pairs. Each of the 12 cells is just a standard 5018LC 3v 1300mAh battery. Newark has them for $6.43 each, so you are still looking at nearly $80 for just the cells. $280 still seems like a bit of a markup for Diamond, though - I don't see the need for the hazardous shipping charge, since it doesn't look like there is any special shipping required if I were to order 12 of them from Newark.

[Gary]

So all the questions prompted me to further disassemble my old battery pack. It turns out the "six" cells are actually 12 cells, heavily shrink-wrapped in pairs. Each of the 12 cells is just a standard 5018LC 3v 1300mAh battery. Newark has them for $6.43 each, so you are still looking at nearly $80 for just the cells. $280 still seems like a bit of a markup for Diamond, though - I don't see the need for the hazardous shipping charge, since it doesn't look like there is any special shipping required if I were to order 12 of them from Newark.

Diamond also has to cover the liability of everything they supply.

[Graham]

While it might be good to save a few dollars, considering when you would need the back-up (IFR and no other instruments) I am not sure I would be comfortable doing it myself. I can just imagine the accident report now....

[Steve]

While it might be good to save a few dollars, considering when you would need the back-up (IFR and no other instruments) I am not sure I would be comfortable doing it myself. I can just imagine the accident report now....

Except that you do have the ability to test it before and after installation...

One could make the same argument about anything the FARs allow the owner to do, like change oil, tires and tubes, etc.

Steve