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Lithium battery on the firewall
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EdKranz

Joined: 29 Dec 2010
Posts: 132
Location: Hastings, MN

Posted: Mon Aug 04, 2014 9:17 am Post subject: Lithium battery on the firewall

I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.Â   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.Â   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/        

  [quote][b]

_________________
Ed Kranz
RV10
Finishing
www.edandcolleen.com

AirMike

Joined: 27 Feb 2007
Posts: 514
Location: Nevada

Posted: Mon Aug 04, 2014 9:40 am Post subject: Re: Lithium battery on the firewall

I do not know very much about lithium batteries, but I would be concerned about the heat up there especially when you shut down on a hot day. That area just stays hot for many hours. Computer lithium batteries are not very stable in heat, but I do not know about the battery that you are talking about. 



Secondly, the RV10 is naturally nose heavy. I keep about 40# of lead in my baggage area when only the front two seats are occupied - this with the battery in the normal area behind the rear bulkhead.



Unless you have a very light composite prop, I am not so sure that this is a good idea. Just another note. If I am not mistaken, I think that an early RV10 fatal crash plane had the battery installed forward of the firewall.

_________________
See you OSH '18
Q/B - sold.

carl.froehlich(at)verizon
Guest

Posted: Mon Aug 04, 2014 9:53 am Post subject: Lithium battery on the firewall

I'm running two PC-625s both located using the per plans placement, but with a custom mount. I note that one PC-625 has more amp-hr capacity than the EXT36C.  I would offer the EXT36C is far too limited on this important aspect.  While a second alternator will mitigate the risk you will need to be thoughtful on how you set up your power distribution so you don't end up with a single failure point taking out all power.  This last piece is not trivial.  The other issue is that while the cold cranking amps is impressive for this product, the low amp-hr rating says you will not have that juice for long.  Note the CCA for two PC-625s in parallel is about the same but for a much longer crank time. My experience is I would not want any less.  There is no free lunch.

Other than reduced wiring I don't see any advantage for mounting any battery on the firewall for an RV-10, and a lot of downside.  Please also note that most W&Bs for RV-10s benefit having the battery(s) mounted in the tail cone.  Compensating with a second alternator will only aggravate the W&B issue.

Carl



On Aug 4, 2014, at 12:16 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

[quote]I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/  to      

   	  Quote: 	
		  



D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

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[b]

partner14

Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas

Posted: Mon Aug 04, 2014 9:57 am Post subject: Lithium battery on the firewall

Probably ok... if you have a std compression engine.  If you have a two blade Hartzel, you're nose heavy in the stock configuration... and now you've take the heaviest thing in the tail, eliminated it, and added more weight in the front.  By yourself in the plane might mean 100 pounds in the baggage area.  Weight is almost always an issue with airplanes, but what I can tell you is the 10 will haul anything!  I just brought back from Calif thru Oregon to Texas 220 lbs of steel angle, 47 lbs of #12 wire rolls, ABS plumbing fittings, a box of 6 new construction recessed cans, golf clubs and our bags.  The only fuel stop from Oregon was Spanish Flats (fuel was $4.95), and the density altitude there was 9,500'.... no issue.

Don McDonald

650 hours and still lovin it!



         From: Ed Kranz <ed.kranz(at)gmail.com>

 To: rv10-list(at)matronics.com 

 Sent: Monday, August 4, 2014 12:16 PM

 Subject: Lithium battery on the firewall

  

 

I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a  structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/        

   	  Quote: 	
		  http://www.matronics.com/Navigator?RV10-="nofollow" target="_blank" href="http://www.matronics.com/contributi==

_________________
Don A. McDonald
40636

jeff(at)westcottpress.com
Guest

Posted: Mon Aug 04, 2014 10:10 am Post subject: Lithium battery on the firewall

I've just caught bits of the Bob Nuckolls discussion of Lithium Batteries on the aeroelectric list. Personally, I wouldn't go near them. Risk/Reward seems upside down.



Jeff Carpenter

40304



On Aug 4, 2014, at 10:16 AM, Ed Kranz wrote:

[quote]I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/        

   	  Quote: 	
		  



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[b]

partner14

Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas

Posted: Mon Aug 04, 2014 10:17 am Post subject: Lithium battery on the firewall

Another note.... because I have a little higher compression, and dual lightspeed elec ignition, I have 2 batteries and 2 alternators.... for 500+ hours and 4.5 years I had 2ea, Odyssey 680's.... since then I replace one of them with one with a little more amperage,,,, maybe the 925, but I can't remember.  It's kind of a nice thing knowing the engine is ALWAYS going to turn over.  It also is recommended by some to run a second ground from the engine to the firewall... not much weight, easy to do, and great insurance.



Don McDonald



        From: Ed Kranz <ed.kranz(at)gmail.com>

 To: rv10-list(at)matronics.com 

 Sent: Monday, August 4, 2014 12:16 PM

 Subject: Lithium battery on the firewall

  

 

I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/        

  [quote]http://www======================


[b]

_________________
Don A. McDonald
40636

rv10pro(at)gmail.com
Guest

Posted: Mon Aug 04, 2014 10:41 am Post subject: Lithium battery on the firewall

Read Jim Weir's article in Kitplanes magazine first. 

John

  On Aug 4, 2014 10:19 AM, "Ed Kranz" <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:[quote] I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.Â     The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.    My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.    I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.Â     Does anyone have any comments about placement or capacity of the battery I'm considering?    http://earthxmotorsports.com/product...ntal-aircraft/                

    	  Quote: 	
		  



get="_blank">http://www.matronics.com/Navigator?RV10-List

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[b]

rv10pro(at)gmail.com
Guest

Posted: Mon Aug 04, 2014 10:42 am Post subject: Lithium battery on the firewall

Dan Lloyd with a Subie. On Aug 4, 2014 10:43 AM, "AirMike" <Mikeabel(at)pacbell.net (Mikeabel(at)pacbell.net)> wrote:[quote] --> RV10-List message posted by: "AirMike" <Mikeabel(at)Pacbell.net>

 

 I do not know very much about lithium batteries, but I would be concerned about the heat up there especially when you shut down on a hot day. That area just stays hot for many hours. Computer lithium batteries are not very stable in heat, but I do not know about the battery that you are talking about.

  

 Secondly, the RV10 is naturally nose heavy. I keep about 40# of lead in my baggage area when only the front two seats are occupied - this with the battery in the normal area behind the rear bulkhead.

 

 Unless you have a very light composite prop, I am not so sure that this is a good idea. Just another note. If I am not mistaken, I think that an early RV10 fatal crash plane had the battery installed forward of the firewall.

  

 --------

 See you OSH '14

 Q/B - flying 4 yrs.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=427948#427948

 

 

 

 

 

 

 

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 [b]

kearney

Joined: 20 Sep 2008
Posts: 563

Posted: Mon Aug 04, 2014 11:24 am Post subject: Lithium battery on the firewall

Hi



Dan's battery was in the tunnel or so I thought. In any event, IIRC, it was not the battery per se that caused his crash. See the NTSB report for info.



I saw the Lithium batteries at KOSH and spoke to the reps. I was impressed until I spoke to retired avionics / electrical tech where I was staying. I can't see the potential risk being worth it especially when weight is needed in the tail for W&B considerations.



I did have two Odyssey batteries mounted on my firewall while I had a Subie installed. I used a couple of battery boxes from Vanâ€™s and tied them into the cross braces that run diagonally on the lower part of the firewall. I donâ€™t know if that would work for the IO540 mount.



Given that I am now retrofitting an IO540 (*sigh*), I have moved the batteries back to the tail. I was able to use battery boxes to make a mount that fits in the stock location and that accommodates the two batteries. 



Cheers



Les



---

EdKranz

Joined: 29 Dec 2010
Posts: 132
Location: Hastings, MN

Posted: Mon Aug 04, 2014 11:27 am Post subject: Lithium battery on the firewall

.... and I don't believe that incident had anything to do with the battery chemistry or location.



On Mon, Aug 4, 2014 at 1:42 PM, John Cox <rv10pro(at)gmail.com (rv10pro(at)gmail.com)> wrote:

 [quote]

Dan Lloyd with a Subie. On Aug 4, 2014 10:43 AM, "AirMike" <Mikeabel(at)pacbell.net (Mikeabel(at)pacbell.net)> wrote:

 	  Quote: 	
		    --> RV10-List message posted by: "AirMike" <Mikeabel(at)Pacbell.net>

 

 I do not know very much about lithium batteries, but I would be concerned about the heat up there especially when you shut down on a hot day. That area just stays hot for many hours. Computer lithium batteries are not very stable in heat, but I do not know about the battery that you are talking about.

   

 Secondly, the RV10 is naturally nose heavy. I keep about 40# of lead in my baggage area when only the front two seats are occupied - this with the battery in the normal area behind the rear bulkhead.

 

 Unless you have a very light composite prop, I am not so sure that this is a good idea. Just another note. If I am not mistaken, I think that an early RV10 fatal crash plane had the battery installed forward of the firewall.

   

 --------

 See you OSH '14

 Q/B - flying 4 yrs.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=427948#427948

 

 

 

 

 

 

 



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 " target="_blank">http://www.matronics.com/Navigator?RV10-List

 ===========

 MS -

 k">http://forums.matronics.com

 ===========

 e -

  Â  Â  Â  Â  Â -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 	


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[b]

_________________
Ed Kranz
RV10
Finishing
www.edandcolleen.com

bwestfall

Joined: 22 Oct 2008
Posts: 131
Location: Portland, OR

Posted: Mon Aug 04, 2014 11:55 am Post subject: Lithium battery on the firewall

It does seem very attractive to me to consider swapping my PC925 for say an EarthX 48E for weigh savings.  The 48E states a 56 min reserve as opposed to the 27 min for the 36.  The swap may potentially allow another 20lbs in the baggage compartment at the cost of $725 for the battery though I would hope to get a lot of life out of it.  It would seem for those 10's w/the lighter composite props on the nose the lighter battery in the tail would be doable.



I'd welcome a discussion about "the potential risks" here for the sake of knowledge.



Ben Westfall

--

n223rv(at)wolflakeairport
Guest

Posted: Mon Aug 04, 2014 1:21 pm Post subject: Lithium battery on the firewall

So I'll counter some ideas on battery placement....  



I travelled to Oshkosh with my wife (pax seat) and two children in the back seats (both under 10 yrs old).  Full camping gear for the week.  At take off and full fuel, I was 50 lbs under gross and CG was good, but as I got down to 16 gallons, I was aft CG.  So I had to place some heavy bags in the back seat floor and I was able to keep CG within specifications all the way to 4 gallons remaining.  



I do have an MT prop (lighter) so maybe if I had a metal prop I'd have been at gross and ok on aft CG, not sure...  I am considering moving my battery forward so I can have more options when fully loaded knowing I'll have to carry dead weight in the baggage compartment when flying solo....



Just another perspective....

-Mike



Sent from my iPhone



[quote] On Aug 4, 2014, at 1:53 PM, Carl Froehlich <carl.froehlich(at)verizon.net> wrote:

 

 I'm running two PC-625s both located using the per plans placement, but with a custom mount. I note that one PC-625 has more amp-hr capacity than the EXT36C.  I would offer the EXT36C is far too limited on this important aspect.  While a second alternator will mitigate the risk you will need to be thoughtful on how you set up your power distribution so you don't end up with a single failure point taking out all power.  This last piece is not trivial.  The other issue is that while the cold cranking amps is impressive for this product, the low amp-hr rating says you will not have that juice for long.  Note the CCA for two PC-625s in parallel is about the same but for a much longer crank time. My experience is I would not want any less.  There is no free lunch.

 

 Other than reduced wiring I don't see any advantage for mounting any battery on the firewall for an RV-10, and a lot of downside.  Please also note that most W&Bs for RV-10s benefit having the battery(s) mounted in the tail cone.  Compensating with a second alternator will only aggravate the W&B issue

speckter(at)comcast.net
Guest

Posted: Mon Aug 04, 2014 2:32 pm Post subject: Lithium battery on the firewall

Wt and balance are the issue here.  Some will tell you that you they don't need any additional wt in the rear when flying solo, but I have found that they compensate by landing faster than needed if the cg is correct. 

The Rans solves this problem by putting lead in the tail cone on the S19.  You might run the cg calculations with this method and see if it is do-able.

Gary



On Aug 4, 2014, at 12:16 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

[quote]aircraft/        [b]

charliewaffles

Joined: 15 Mar 2011
Posts: 18

Posted: Mon Aug 04, 2014 4:24 pm Post subject: Re: Lithium battery on the firewall

A couple of things come to mind as I am working through this same issue.



The EarthX 36 is LOWER reserve/usable capacity than the PC925. They do not recommend this as a swap for the 925. 



I currently have an EarthX 48E sitting on my bench waiting for install. However, my plane is to install it in the tail in the original battery mount. My intent is to remove the dead weight that I can't manage and the impact on CG. I already fly with a 25lb bag of shot when flying solo, so I can easily bump that up to accomodate the 20lb loss. But when I am flying with a full bird, it then becomes weight I can move and affect CG and loading much better. I've already had issues where the plane was loaded to the point that I was close to dropping the tail, so the ability to move that big of a weight moment is very helpful.



EarthX also estimates their batteries to be about an 8 year lifetime, so considerably longer than the Odyssey PC925. So on a yearly basis the numbers should work out to be about the same.

partner14

Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas

Posted: Mon Aug 04, 2014 5:40 pm Post subject: Lithium battery on the firewall

Mike, the back seats are so big.... put some heavier items in front of your kids feet.

        From: Michael Kraus <n223rv(at)wolflakeairport.net>

 To: "rv10-list(at)matronics.com" <rv10-list(at)matronics.com> 

 Sent: Monday, August 4, 2014 4:21 PM

 Subject: Re:  Lithium battery on the firewall

So I'll counter some ideas on battery placement....  

I travelled to Oshkosh with my wife (pax seat) and two children in the back seats (both under 10 yrs old).  Full camping gear for the week.  At take off and full fuel, I was 50 lbs under gross and CG was good, but as I got down to 16 gallons, I was aft CG.  So I had to place some heavy bags in the back seat floor and I was able to keep CG within specifications all the way to 4 gallons remaining.  

I do have an MT prop (lighter) so maybe if I had a metal prop I'd have been at gross and ok on aft CG, not sure...  I am considering moving my battery forward so I can have more options when fully loaded knowing I'll have to carry dead weight in the baggage compartment when flying  solo....

Just another perspective....

-Mike

Sent from my iPhone

On Aug 4, 2014, at 1:53 PM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:

[quote]

I'm running two PC-625s both located using the per plans placement, but with a custom mount. I note that one PC-625 has more amp-hr capacity than the EXT36C.  I would offer the EXT36C is far too limited on this important aspect.  While a second alternator will mitigate the risk you will need to be thoughtful on how you set up your power distribution so you don't end up with a single failure point taking out all power.  This last piece is not trivial.  The other issue is that while the cold cranking amps is impressive for this  product, the low amp-hr rating says you will not have that juice for long.  Note the CCA for two PC-625s in parallel is about the same but for a much longer crank time. My experience is I would not want any less.  There is no free lunch.

Other than reduced wiring I don't see any advantage for mounting any battery on the firewall for an RV-10, and a lot of downside.  Please also note that most W&Bs for RV-10s benefit having the battery(s) mounted in the tail cone.  Compensating with a second alternator will only aggravate the W&B issue.

Carl

On Aug 4, 2014, at 12:16 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

 	  Quote: 	
		  I'm strongly considering using an EarthX EXT36C Lithium battery on the firewall of my 10 instead of in the stock battery box in the tail. A buddy did a structural analysis, and there are no issues structurally, by a good margin. What I'm wondering about is placement. The two places that look like good candidates are on the upper firewall between the brake reservoir and the firewall recess, or centered below the brake reservoir.   The battery I'm considering is very small and light (5.9" x 3.4" x 5.4", 3.5lbs), but still has 680 cranking amps, and importantly in Minnesota, 405 cold cranking amps. I think that this combined with the MUCH shorter wire runs to the starter should give me great starting power.  My original plan was for a PC925 in the tail. This would be a 22.5 lb reduction for me with only the battery, plus the weight of that big #2 cable that will get a lot shorter.  I am also planning a TCW Backup Battery for critical avionics, and a secondary alternator.   Does anyone have any comments about placement or capacity of the battery I'm considering?  http://earthxmotorsports.com/product...ntal-aircraft/  to      

   	  Quote: 	

D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

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_________________
Don A. McDonald
40636

EdKranz

Joined: 29 Dec 2010
Posts: 132
Location: Hastings, MN

Posted: Mon Aug 04, 2014 5:47 pm Post subject: Lithium battery on the firewall

You bring up a point I've seen a few people write about, and I admit, I'm not sure I fully understand.

What do we really need starter battery capacity for? I'm planning on a primary and secondary alternator, as well as a backup TCW battery for critical avionics (PFD, GTN, etc). Possibly a second TCW backup battery for electronic ignition, depending on what I decide to do with that. The capacity of the starter battery will become the 4th redundancy in an electrical system failure. 

 



Other than an electrical emergency, isn't the ship's battery capacity mostly just useful for starting the motor? I don't know how many amp-hours is used during, say a 10 second crank. 



 



On Mon, Aug 4, 2014 at 7:24 PM, charliewaffles <mcooper(at)live.com (mcooper(at)live.com)> wrote:

[quote] --> RV10-List message posted by: "charliewaffles" <mcooper(at)live.com (mcooper(at)live.com)>

 

 A couple of things come to mind as I am working through this same issue.

 

 The EarthX 36 is LOWER reserve/usable capacity than the PC925. They do not recommend this as a swap for the 925.

 

 I currently have an EarthX 48E sitting on my bench waiting for install. However, my plane is to install it in the tail in the original battery mount. My intent is to remove the dead weight that I can't manage and the impact on CG. I already fly with a 25lb bag of shot when flying solo, so I can easily bump that up to accomodate the 20lb loss. But when I am flying with a full bird, it then becomes weight I can move and affect CG and loading much better. I've already had issues where the plane was loaded to the point that I was close to dropping the tail, so the ability to move that big of a weight moment is very helpful.

  

 EarthX also estimates their batteries to be about an 8 year lifetime, so considerably longer than the Odyssey PC925. So on a yearly basis the numbers should work out to be about the same.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=427987#427987

 

 

 

 

 

 

 

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 " target="_blank">http://www.matronics.com/Navigator?RV10-List

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 e -

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 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

_________________
Ed Kranz
RV10
Finishing
www.edandcolleen.com

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Aug 04, 2014 6:16 pm Post subject: Lithium battery on the firewall

It depends entirely on how you are designing your electrical system. If you have electronic ignition, a battery needs to be your primary backup. A backup alternator is a nice secondary backup.

 

Ditto instrument panel. If you rely on glass panels for primary IFR display, then you need something, whether mechanical or independent electrical as backup display.



I have chosen to have a single alternator, a single main ship's battery, with dual displays, dual ADAHARs, with independent backup batteries for each display. I am using two magnetos for ignition. IOW, very old school except for the glass panels. My ship's battery is the primary backup to the alternator. After the ship's battery drops below 12.3 volts, the EFIS backup batteries take over. So Ship's battery is of paramount concern to me. I want around 30-40 minutes power with a navcom and a glass panel powered before I go to EFIS only with all radios and transponder shutdown. At that point I get another 45 min before the first EFIS quits and I turn the second back on to give me another 45 min.  So I should have 2  hours before I lose all electrical and instrument display. If I haven't either gotten on the ground or found VFR in 2 hours I have made multiple mistakes.

 

The Odyssey 925 looks to be very comparable in capacity to the RG25 Van's planned for. Engine starting is the least important use of the ship's battery IMHO.



 

On Mon, Aug 4, 2014 at 6:46 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

[quote] You bring up a point I've seen a few people write about, and I admit, I'm not sure I fully understand.

What do we really need starter battery capacity for? I'm planning on a primary and secondary alternator, as well as a backup TCW battery for critical avionics (PFD, GTN, etc). Possibly a second TCW backup battery for electronic ignition, depending on what I decide to do with that. The capacity of the starter battery will become the 4th redundancy in an electrical system failure. 

  



Other than an electrical emergency, isn't the ship's battery capacity mostly just useful for starting the motor? I don't know how many amp-hours is used during, say a 10 second crank. 

 

 

 

 

 Read this topic online here:

 

 

 	  Quote: 	
		  http://forums.matronics.com/viewtopic.php?p=427987#427987 

 

 

 

 

 

 

   

 

 

 





get="_blank">http://www.matronics.com/Navigator?RV10-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

saylor.dave(at)gmail.com
Guest

Posted: Mon Aug 04, 2014 6:31 pm Post subject: Lithium battery on the firewall

I think the idea is that if you use a starting battery that's a little bigger than you need for starting, you can also use it as one of the redundancies. Â So in your case if you use something with the capacity of a 925, you might do without the extra alternator.   



Another reason for extra starting capacity is that sometimes starting can be a challenge. Â Yes, good maintenance and EI can make starting easier, but extra capacity can be a big help too. Â I've learned that my engine, for example, usually fires on a hot start about four blades after I hear the starter start to complain. Â And, I can run the panel for a few minutes with any anxiety about what I'm doing to the battery. Â So a little extra is nice to have. Â So is a ground power plug, big enough for starting.   



Ed, keep in mind that you're proposing a fairly complex system with a lot of interconnects and maybe a few unknowns. Â Ideally each component is transparent and just "works" but in my experience it's usually not that simple.

   



--Dave

PP 60A, PC 925, TCW backup for AP & GNS, Internal batts for EFIS 1, 2, & GPS 2





  



On Mon, Aug 4, 2014 at 6:46 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

[quote]  You bring up a point I've seen a few people write about, and I admit, I'm not sure I fully understand.

What do we really need starter battery capacity for? I'm planning on a primary and secondary alternator, as well as a backup TCW battery for critical avionics (PFD, GTN, etc). Possibly a second TCW backup battery for electronic ignition, depending on what I decide to do with that. The capacity of the starter battery will become the 4th redundancy in an electrical system failure. 

   



Other than an electrical emergency, isn't the ship's battery capacity mostly just useful for starting the motor? I don't know how many amp-hours is used during, say a 10 second crank. 



   



On Mon, Aug 4, 2014 at 7:24 PM, charliewaffles <mcooper(at)live.com (mcooper(at)live.com)> wrote:

 	  Quote: 	
		     --> RV10-List message posted by: "charliewaffles" <mcooper(at)live.com (mcooper(at)live.com)>

 

 A couple of things come to mind as I am working through this same issue.

 

 The EarthX 36 is LOWER reserve/usable capacity than the PC925. They do not recommend this as a swap for the 925.

 

 I currently have an EarthX 48E sitting on my bench waiting for install. However, my plane is to install it in the tail in the original battery mount. My intent is to remove the dead weight that I can't manage and the impact on CG. I already fly with a 25lb bag of shot when flying solo, so I can easily bump that up to accomodate the 20lb loss. But when I am flying with a full bird, it then becomes weight I can move and affect CG and loading much better. I've already had issues where the plane was loaded to the point that I was close to dropping the tail, so the ability to move that big of a weight moment is very helpful.

    

 EarthX also estimates their batteries to be about an 8 year lifetime, so considerably longer than the Odyssey PC925. So on a yearly basis the numbers should work out to be about the same.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=427987#427987

 

 

 

 

 

 

 

 ===========

 " target="_blank">http://www.matronics.com/Navigator?RV10-List

 ===========

 MS -

 k">http://forums.matronics.com

 ===========

 e -

  Â  Â  Â  Â  Â -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 



get="_blank">http://www.matronics.com/Navigator?RV10-List

tp://forums.matronics.com

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[b]

flying-nut(at)cfl.rr.com
Guest

Posted: Mon Aug 04, 2014 6:39 pm Post subject: Lithium battery on the firewall

Starters can draw about 200 amps from a       new battery when cranking.Â  Add cold weather and CCA goes down       along with increased drag of thick oil and some age ..... not a       pretty combination.Â  After starting the battery load is really       small, especially with the new avionics designs so I'd guess you       could run out of gas before you depleted the battery.Â  Just       depends on what you can shut down .... strobes and transponder are       good current suckers.

       

       The CCA is the batteries capacity and is the number of amps a       battery can deliver over 30 seconds at zero degrees F ..... before       the battery voltage drops to 7.2 volts.

       

       

       Linn

       

       

       On 8/4/2014 9:46 PM, Ed Kranz wrote:

     

     [quote]                           You bring up a point I've seen a few people write about,             and I admit, I'm not sure I fully understand.

             

           

           What do we really need starter battery capacity for? I'm           planning on a primary and secondary alternator, as well as a           backup TCW battery for critical avionics (PFD, GTN, etc).           Possibly a second TCW backup battery for electronic ignition,           depending on what I decide to do with that. The capacity of           the starter battery will become the 4th redundancy in an           electrical system failure. 

           

         

         Other than an electrical emergency, isn't the ship's battery         capacity mostly just useful for starting the motor? I don't know         how many amp-hours is used during, say a 10 second crank. 

         

         

       

       

         

         On Mon, Aug 4, 2014 at 7:24 PM,           charliewaffles <mcooper(at)live.com (mcooper(at)live.com)>           wrote:

            	  Quote: 	
		               --> RV10-List message posted by: "charliewaffles" <mcooper(at)live.com (mcooper(at)live.com)>

             

             A couple of things come to mind as I am working through this             same issue.

             

             The EarthX 36 is LOWER reserve/usable capacity than the             PC925. They do not recommend this as a swap for the 925.

             

             I currently have an EarthX 48E sitting on my bench waiting             for install. However, my plane is to install it in the tail             in the original battery mount. My intent is to remove the             dead weight that I can't manage and the impact on CG. I             already fly with a 25lb bag of shot when flying solo, so I             can easily bump that up to accomodate the 20lb loss. But             when I am flying with a full bird, it then becomes weight I             can move and affect CG and loading much better. I've already             had issues where the plane was loaded to the point that I             was close to dropping the tail, so the ability to move that             big of a weight moment is very helpful.

             

             EarthX also estimates their batteries to be about an 8 year             lifetime, so considerably longer than the Odyssey PC925. So             on a yearly basis the numbers should work out to be about             the same.

             

             

             

             

             Read this topic online here:

             

             http://forums.matronics.com/viewtopic.php?p=427987#427987

             

             

             

             

             

             

             

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             t="_blank">http://www.matronics.com/contribution

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         Checked by AVG - www.avg.com

         08/04/14     [b]

carl.froehlich(at)verizon
Guest

Posted: Mon Aug 04, 2014 6:54 pm Post subject: Lithium battery on the firewall

There is nothing as reliable as a maintained battery.  As such the battery(s) provides the foundation for electrical power distribution capacity calculations.  The other issue is the confidence of design that a single point failure will not take out non-vital power distibution.  A classic example of this is a twin engine plane having two alternators and two batteries but a common master buss.  This led to a twin having sudden and total loss of all power when the common buss failed as a result of a high resistance connection.

For me I used a design criteria of 2 hours of IFR flight using just one of the two installed PC-625 batteries and no altenator.  This is the "must have battery amp-hr capacity" for my plane.  Here again one must be thorough in design to make sure that under practical failure modes at least one battery can always be directed to the avionic loads.  If you are running dual LightSpeed ignitions this criterial becomes exceptionally important.

Some procedural rules follow.  For example if one flogs a battery(s) into the ground on a hard start the reserve amp-hr capacity will not be available for at least the first part of the flight.  Another example is leaving a master on.  At this point even if you can breath some life back into it the battery, capacity is compromised and it should be replaced.  As an alternative to doing periodic battery discharge testing to verify amp-hr capacity I just replace one of the two PC-625 batteries every two years.  The pulled batteries end up providing many years of service in tractors here at the airpark.

 

Carl



On Aug 4, 2014, at 8:46 PM, Ed Kranz <ed.kranz(at)gmail.com (ed.kranz(at)gmail.com)> wrote:

[quote]You bring up a point I've seen a few people write about, and I admit, I'm not sure I fully understand.

What do we really need starter battery capacity for? I'm planning on a primary and secondary alternator, as well as a backup TCW battery for critical avionics (PFD, GTN, etc). Possibly a second TCW backup battery for electronic ignition, depending on what I decide to do with that. The capacity of the starter battery will become the 4th redundancy in an electrical system failure. 

 



Other than an electrical emergency, isn't the ship's battery capacity mostly just useful for starting the motor? I don't know how many amp-hours is used during, say a 10 second crank. 



 



On Mon, Aug 4, 2014 at 7:24 PM, charliewaffles <mcooper(at)live.com (mcooper(at)live.com)> wrote--> RV10-List message posted by: "charliewaffles" <mcooper(at)live.com (mcooper(at)live.com)> 	  Quote: 	
		  A couple of things come to mind as I am working through this same issue

 The EarthX 36 is LOWER reserve/usable capacity than the PC925. They do not recommend this as a swap for the 925.

 

 I currently have an EarthX 48E sitting on my bench waiting for install. However, my plane is to install it in the tail in the original battery mount. My intent is to remove the dead weight that I can't manage and the impact on CG. I already fly with a 25lb bag of shot when flying solo, so I can easily bump that up to accomodate the 20lb loss. But when I am flying with a full bird, it then becomes weight I can move and affect CG and loading much better. I've already had issues where the plane was loaded to the point that I was close to dropping the tail, so the ability to move that big of a weight moment is very helpful.

  

 EarthX also estimates their batteries to be about an 8 year lifetime, so considerably longer than the Odyssey PC925. So on a yearly basis the numbers should work out to be about the same.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=427987#427987

 

 

 

 

 

 

 

 ===========

 " target="_blank">http://www.matronics.com/Navigator?RV10-List

 ===========

 MS -

 k">http://forums.matronics.com

 ===========

 e -

           -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 



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