Dual Battery Setup


 

So I have been doing some reading and research on battery backup setups and it seems that the most common design is a smaller battery that runs only an emergency bus, separate from the main bus. This setup makes sense, when you consider how heavy full size batteries are but I have an idea I'd like to thoughts on ... What if I have 2 same EarthX batteries which are considerable lighter while more expensive, running in parallel?

For background, I will be running electronic ignition and fuel injection so battery power is key to my O-200 Quickie. With a simple 2 battery setup, they can run in parallel and both can be charged at the same time. Then add a switch that turns on both relays or one or the other battery, to the main bus (coils & ignition) and my VPX (everything else electrical).

Here is yet again my simple drawing for reference ... no comments on my drawing skills please ;-)



Appreciate your thoughts & comments and a HAPPY 4TH OF JULY!!!

--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Corbin <c_geiser@...>
 

I don’t see why that wouldn’t work at 4.1lbs each.  I’m using the one below as my backup.  It’s small and just over 1 lb.  I think it will run one electric coil and a pump for something crazy like 3-4 hours.  And that’s after your main battery depleted itself.

https://www.aircraftspruce.com/catalog/elpages/tcwbackup11-12650-3.php

Corbin
--

Corbin 
N121CG


Kevin R. Walsh
 



On Mon, Jul 4, 2022 at 11:16 AM Robert Schmid <robert@...> wrote:
So I have been doing some reading and research on battery backup setups and it seems that the most common design is a smaller battery that runs only an emergency bus, separate from the main bus.
_._,_._,_

I suggest you look into Bob Nuckols and the AeroElectric Connection. He has done a life’s work in electrical systems for E-AB planes, and his “Z” diagrams are a good place to start.
--
Kevin


 

Here is an interesting article by him ... http://www.aeroelectric.com/articles/bat_iso2.pdf
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Robert Cringely
 

A two-battery setup makes good sense.  I run a similar system on my Thorp T-18, which has dual P-Mags. 

Batteries have improved dramatically and you would be crazy to use lead acid or AGM batteries today. The technology to go for is lithium-iron-phosphate because it doesn't burn like lithium-ion or lithium-polymer and plays nicely with old-school charging systems. Any 8 Ah LiFePO4 motorcycle battery will work as a single power source for a Q-200. If you go with two batteries consider 2X5 Ah. I have built my own batteries from cells, but motorcycle battery prices are so low now it isn't worth the trouble.

Notice I specify motorcycle -- not aircraft -- batteries. The TSO isn't worth the 3-4X premium for aircraft batteries. Just check around and make sure you aren't the first person using that battery in an airplane. Be an early adopter, not a pioneer.

And keep an eye on CG movement with these changes, because pulling 10+ lbs out of your Q-200 can move things around. 

On my T-18 I am finishing-up a weight reduction program involving a new starter, alternator, batteries, composite propeller blades, Vetterman exhaust, titanium tailwheel spring, and carbon prepreg stabilator and main landing gear for a total empty weight reduction from 1002 lbs to 862!  Now it's time for me to lose some weight, too.

On Mon, Jul 4, 2022 at 11:27 AM Corbin via groups.io <c_geiser=icloud.com@groups.io> wrote:
I don’t see why that wouldn’t work at 4.1lbs each.  I’m using the one below as my backup.  It’s small and just over 1 lb.  I think it will run one electric coil and a pump for something crazy like 3-4 hours.  And that’s after your main battery depleted itself.

https://www.aircraftspruce.com/catalog/elpages/tcwbackup11-12650-3.php

Corbin
--

Corbin 
N121CG


Sam Hoskins
 

First off, you should have a copy of Bob Nuckolls Aeroelectric book.

I have a fuel injection system with electronic ignition. I use two Odyssey P625 batteries.I'll make a PDF of my current system and get it uploaded to the file section.

Sam

On Mon, Jul 4, 2022, 1:16 PM Robert Schmid <robert@...> wrote:
So I have been doing some reading and research on battery backup setups and it seems that the most common design is a smaller battery that runs only an emergency bus, separate from the main bus. This setup makes sense, when you consider how heavy full size batteries are but I have an idea I'd like to thoughts on ... What if I have 2 same EarthX batteries which are considerable lighter while more expensive, running in parallel?

For background, I will be running electronic ignition and fuel injection so battery power is key to my O-200 Quickie. With a simple 2 battery setup, they can run in parallel and both can be charged at the same time. Then add a switch that turns on both relays or one or the other battery, to the main bus (coils & ignition) and my VPX (everything else electrical).

Here is yet again my simple drawing for reference ... no comments on my drawing skills please ;-)



Appreciate your thoughts & comments and a HAPPY 4TH OF JULY!!!

--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Jay Scheevel
 

Definitely should read Bob Nuckol’s stuff. I did so thoroughly and also had some phone discussions with him before I designed my rather complex wiring system. I run two EarthX batteries in parallel, similar (but not the same) as what you describe.

 

In my system, main and aux batteries are identical and can run together, one at a time, or both off (provided alternator is turning out current), and everything electric works under any scenario. In my system, if the battery is on, it is also being charged by the alternator. The engine can be started on one or both batteries. I usually start it with both.

 

My design has performed flawlessly in my plane for 4 years. I use two independent master solenoids. One for each battery. Not sure there is a 3-way solenoid connector that can handle the starting loads, so that may be flaw with your design. 

 

Here is my schematic for my plane (http://n8wq.scheevel.com/documents/Main_electrical_schematic3.pdf ). Have a look at the last ten pages of the following pdf to get an idea what my battery installation looks like http://n8wq.scheevel.com/documents/build_logs/10_N8WQ-log_Panel_Electrics_Avionics.pdf .

 

Cheers,

Jay

 

 

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Kevin R. Walsh
Sent: Monday, July 4, 2022 1:00 PM
To: main@q-list.groups.io
Subject: Re: [Q-List] Dual Battery Setup

 

 

 

On Mon, Jul 4, 2022 at 11:16 AM Robert Schmid <robert@...> wrote:

So I have been doing some reading and research on battery backup setups and it seems that the most common design is a smaller battery that runs only an emergency bus, separate from the main bus.


 

Fig 2 in the link looks quite similar in its basics to my drawing, considering I get my "low voltage" voice annunciation from my EFIS which then enables me to do the right battery and components switching.


The one thing I will think about a bit more is this logical split between an essential and master bus ... Hmmm
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Sam Hoskins
 

When you have an airplane that depends on electrical power to stay in the air, you have to make sure that if the alternator fails you can still get where you want to go.

One of the things you need to do in this whole thing is a load analysis. Get a spreadsheet going and put in every electrical component and how much power it will use. That will help you determine what size battery you need to complete whatever mission you are flying. I had an instance where my alternator failed and I was was about an hour and 15 minutes away from home. With my two batteries I know I have about three hours of flight time available.

Your configuration will require some careful consideration.

Sam 

On Mon, Jul 4, 2022, 1:16 PM Robert Schmid <robert@...> wrote:
So I have been doing some reading and research on battery backup setups and it seems that the most common design is a smaller battery that runs only an emergency bus, separate from the main bus. This setup makes sense, when you consider how heavy full size batteries are but I have an idea I'd like to thoughts on ... What if I have 2 same EarthX batteries which are considerable lighter while more expensive, running in parallel?

For background, I will be running electronic ignition and fuel injection so battery power is key to my O-200 Quickie. With a simple 2 battery setup, they can run in parallel and both can be charged at the same time. Then add a switch that turns on both relays or one or the other battery, to the main bus (coils & ignition) and my VPX (everything else electrical).

Here is yet again my simple drawing for reference ... no comments on my drawing skills please ;-)



Appreciate your thoughts & comments and a HAPPY 4TH OF JULY!!!

--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Chris Walterson
 

What I did on my very old Dragonfly with the EA81 was to use only one battery.  I choose to use a lawn tractor battery. It weighs 18 lbs is 325 Amp and is non venting.

Roger Enns, a fellow builder came up with the idea of installing a capasitor in line of the alternator field line. This way, once it is running it will run with the battery taken out of the system or it will run only on the battery with the alternator taken out of the system.

 I have seen alternators short out and catch fire and I have seen batteries blow up. This system gives you the chance to use alternator only , or battery only. Luckily, never had to use it. Take care---------  Chris


--
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Well it looks like there is good precedence for two identical batteries and it can be done, though with a few modifications. I will now go back and draw this all up in more detail, with your input and including my VPX setup.

Thanks for everyones help!
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Jay Scheevel
 

Probably don’t need to do that much designing, Robert. If your alternator and regulator are running, voltage will be system charging voltage at both batteries. If no alternator, then you can switch to the the battery of your choice and the system voltage will be that of the active battery. If using the EarthX batteries, they each have a battery fault external feed wire that you can connect to your EFIS to get the alarm warning through the EFIS.

What Sam says is right. Make sure your battery package can run all systems long enough to get you to a comfortable destination. My batteries will run everything without an alternator for 1.5 hours.

Cheers,
Jay 


On Jul 4, 2022, at 1:51 PM, Robert Schmid <robert@...> wrote:

Fig 2 in the link looks quite similar in its basics to my drawing, considering I get my "low voltage" voice annunciation from my EFIS which then enables me to do the right battery and components switching.

dummyfile.0.part
The one thing I will think about a bit more is this logical split between an essential and master bus ... Hmmm
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.