Question about the backup battery.

Any DA40 related topics

Moderators: Rick, Lance Murray

User avatar
Don
4 Diamonds Member
4 Diamonds Member
Posts: 377
Joined: Tue Jul 06, 2010 9:15 pm
First Name: Don
Aircraft Type: DA40
Aircraft Registration: N623DS
Airports: KTOA
Has thanked: 123 times
Been thanked: 162 times

Question about the backup battery.

Post by Don »

Does anyone know if the backup battery behind the panel gets recharged during flight or is just charged once at the factory?

Thanks,
Don
Diamond Star XLS, N623DS, SN40.1076
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Question about the backup battery.

Post by Rick »

Assuming you are talking about the Li-ion battery pack that is energized by the "Emergency" switch on the panel, it is completely disconnected from the aircraft electrical system when the switch is off. So no charging ever happens in the plane. This applies to the original AA-cell battery pack as well.
Roanoke, VA (KROA)
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Question about the backup battery.

Post by Rich »

Lithium in a battery does not automatically equate to what we refer to as lithium-Ion. Further, not all lithium-based batteries are secondary (rechargeable). There are many different chemistries of lithium-anode batteries. Some are primary and some secondary. I have a Lithium Iron Phosphate in my motorcycle as a substitute for the much heavier Lead-acid OEM battery. It is, of course, a secondary type.

I have used primary lithium batteries in headsets. Use 'em up and throw 'em away. I don't know if these can be recycled.
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
User avatar
Rick
5 Diamonds Member
5 Diamonds Member
Posts: 1575
Joined: Tue Jul 06, 2010 10:09 pm
First Name: Rick
Aircraft Type: DA40
Aircraft Registration: NONE
Airports: KROA
Has thanked: 107 times
Been thanked: 297 times

Re: Question about the backup battery.

Post by Rick »

Yikes! I forgot you are a battery expert - I should have thought a bit more about how I identified the battery! :bow

The one emergency battery pack I cut open simply contained 8 Panasonic CR123A batteries wired in series. Every battery pack I have replaced over the years has measured the same voltage when I took it out as the new replacement I was installing. Given that the battery pack just sits in the plane for 2 years, disconnected, I guess that would be expected.
DSC01593a.jpg
Roanoke, VA (KROA)
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Question about the backup battery.

Post by Rich »

Rick wrote: Thu Aug 20, 2020 11:48 pm Yikes! I forgot you are a battery expert - I should have thought a bit more about how I identified the battery! :bow

The one emergency battery pack I cut open simply contained 8 Panasonic CR123A batteries wired in series. Every battery pack I have replaced over the years has measured the same voltage when I took it out as the new replacement I was installing. Given that the battery pack just sits in the plane for 2 years, disconnected, I guess that would be expected.DSC01593a.jpg
Too bad Diamond didn't set this up like they did with the AA Duracells, where you buy a few relatively cheap batteries and replace them in a reusable carrier. These CR123A cells themselves are relatively inexpensive, though more limited in what you could use them for after replacement. Effectively the AA Duracells are free.

In my plane the emergency pack is only available for the AI and floodlight. Unless I lose electrical power at night, I wouldn't need both. If it happened in day IMC, only the AI. With new electronic AI's now routinely having their own backup battery, the equation is changed. And with the way I now use my iPad, the floodlight probably also becomes redundant.
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
User avatar
Boatguy
5 Diamonds Member
5 Diamonds Member
Posts: 1827
Joined: Mon Jan 22, 2018 4:48 am
First Name: Russ
Aircraft Type: DA62
Aircraft Registration: N962M
Airports: KSTS
Has thanked: 1327 times
Been thanked: 1163 times

Re: Question about the backup battery.

Post by Boatguy »

How about we install a GI-275 and remove the battery pack, flood light strip and switch entirely?
User avatar
Steve
5 Diamonds Member
5 Diamonds Member
Posts: 1953
Joined: Thu Aug 12, 2010 1:23 am
First Name: Steve
Aircraft Type: DA40
Aircraft Registration: N432SC
Airports: 1T7
Has thanked: 81 times
Been thanked: 493 times

Re: Question about the backup battery.

Post by Steve »

Boatguy wrote: Sat Aug 22, 2020 12:19 am How about we install a GI-275 and remove the battery pack, flood light strip and switch entirely?
Russ:

The backup battery powers only the AI and pilot's map light. The flood is powered off the lighting bus. Apart from that, I don't think you could do that without a 337, and maybe not even then, since the airplane was certified with a backup battery-powered light. One of the many reasons the Experimental world is much more...


...reasonable.

Steve
User avatar
Boatguy
5 Diamonds Member
5 Diamonds Member
Posts: 1827
Joined: Mon Jan 22, 2018 4:48 am
First Name: Russ
Aircraft Type: DA62
Aircraft Registration: N962M
Airports: KSTS
Has thanked: 1327 times
Been thanked: 1163 times

Re: Question about the backup battery.

Post by Boatguy »

My plane does not have a "lighting" bus. The flood light and backup AI, are powered by the Essential bus in the event of alternator failure, and then the backup battery after the main battery is depleted. From the AFM:

"In addition, a non-rechargeable dry battery is installed in the I FR model as a further source
of power for the attitude gyro (artificial horizon) and the flood light. When the EMERGENCY
switch is set to ON, these two systems are supplied with power for 1 hour, independent
of all other electrical consumers. During each 100 hour inspection , this battery is checked
for proper functioning. Every 2 years or after use (broken seal on the switch) the battery
pack must be replaced."

But you are correct that the battery and flood light are part of the KOEL in the AFM; don't leave home without them.

But since it would be less expensive for Diamond, in both parts and labor, to eliminate the battery, switch, backup altimeter, backup AI and backup airspeed, I would not be surprised if they re-certified the plane with a GI-275, or even two. They have to periodically re-certify the plane anyway for avionics changes. I think they could convince Transport Canada that the self contained GI-275 is more reliable than three analog electro-mechanical devices, one of which requires a backup battery and all of which require external illumination.

And then I can "update" my plane to a currently certified configuration and be entirely legal, just as owners can update a non-WAAS airplane to WAAS.

Hope springs eternal!
User avatar
Steve
5 Diamonds Member
5 Diamonds Member
Posts: 1953
Joined: Thu Aug 12, 2010 1:23 am
First Name: Steve
Aircraft Type: DA40
Aircraft Registration: N432SC
Airports: 1T7
Has thanked: 81 times
Been thanked: 493 times

Re: Question about the backup battery.

Post by Steve »

Ah, I see that you have an NG. You are correct, the Flood is powered from the Essential Bus, but the backup battery on mine does not power the Flood (or anything else on the Essential Bus) in any configuration. Only the Pilot's map light and the AI. I dutifully replace the AA Duracells every 2 years, and measure the voltage at every Annual Inspection. One of these days, I'm going to flip the Emergency switch during the Annual, and see how long they last.

Steve
User avatar
Boatguy
5 Diamonds Member
5 Diamonds Member
Posts: 1827
Joined: Mon Jan 22, 2018 4:48 am
First Name: Russ
Aircraft Type: DA62
Aircraft Registration: N962M
Airports: KSTS
Has thanked: 1327 times
Been thanked: 1163 times

Re: Question about the backup battery.

Post by Boatguy »

Steve wrote: Sat Aug 22, 2020 1:47 am One of these days, I'm going to flip the Emergency switch during the Annual, and see how long they last.
That's a great idea! I think somebody else said they measured the voltage. But yeah, turn it on since we have to pay to replace it anyway!
Post Reply