Sailplane Power Supply

[Andrey Lebedev]

Hello group,

I did a wiring overhaul in my cockpit recently. I learned a lot in the process and decided to document my research for various ways you can connect batteries to your electronics. Hopefully this will be helpful to folks like me half a year ago.

https://medium.com/taming-a-sailplane/sailplane-power-supply-479b6632fedd

For my ship I've chosen scheme I call "Commuted circuits". I must admit I was pretty amazed by elegance of the solution.

Any feedback, especially practical experience, is highly appreciated.

--
Andrey Lebedev
WU

[Charlie M. (UH & 002 owner/pilot)]

Nice writeup and diagrams.
What I, and others, do is similar to one of yours.
Behind the panel, there is a single "common buss" for "+" and "-" that feeds all devices. Feeding that are 2 batteries, each with their own simple on/off master switch.
You then have 3 modes of operation:
-feed everything from battery 1
-feed everything from battery 2
-feed everything from both batteries at once. There is the previously stated issue regarding batteries at different states of charge, different ages, etc.

Plenty of our electronics can display battery voltage or add in a simple panel voltmeter to watch the "device side of the buss" to monitor battery/system voltage.
When voltage gets low, turn on the second battery and THEN turn off the first battery so everything remains powered.

I like to use screw type terminal strips to make it easier to add/remove devices.

These are nice since they've harder to short out.....
http://www.mouser.com/ProductDetail/TE-Connectivity/1776293-5/?qs=bdENzIhz2rlx1zfI7zIhoQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF9MgBsB6Nbc_wifpgMGJfXW1nRYf20nUY6nfHlt tzIEaApPW8P8HAQ

These can be used with ring or fork terminals.....
http://www.mouser.com/ProductDetail/Eaton/KU4-00WCMT/?qs=1zthkiRbLn1IbrW0cLoSdQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF__JCJYtRxzYfMAm0tylQVAdAQUAoB7_gqtJqTJ nNsEaAm_D8P8HAQ

[Andy Blackburn[_3_]]

I've concluded that this is the best solution, with one modification - each battery is connected through and ideal diode so there is no cross-charging.. Unlike Schottky diodes, which have on the order of a 0.5 volt drop at typical glider panel currents, ideal diodes have only a 0.03 volt drop up to about 10 amps.

9B

On Friday, January 27, 2017 at 12:38:59 PM UTC-8, Charlie M. (UH & 002 owner/pilot) wrote:
> Nice writeup and diagrams.
> What I, and others, do is similar to one of yours.
> Behind the panel, there is a single "common buss" for "+" and "-" that feeds all devices. Feeding that are 2 batteries, each with their own simple on/off master switch.
> You then have 3 modes of operation:
> -feed everything from battery 1
> -feed everything from battery 2
> -feed everything from both batteries at once. There is the previously stated issue regarding batteries at different states of charge, different ages, etc.
>
> Plenty of our electronics can display battery voltage or add in a simple panel voltmeter to watch the "device side of the buss" to monitor battery/system voltage.
> When voltage gets low, turn on the second battery and THEN turn off the first battery so everything remains powered.
>
> I like to use screw type terminal strips to make it easier to add/remove devices.
>
> These are nice since they've harder to short out.....
> http://www.mouser.com/ProductDetail/TE-Connectivity/1776293-5/?qs=bdENzIhz2rlx1zfI7zIhoQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF9MgBsB6Nbc_wifpgMGJfXW1nRYf20nUY6nfHlt tzIEaApPW8P8HAQ
>
> These can be used with ring or fork terminals.....
> http://www.mouser.com/ProductDetail/Eaton/KU4-00WCMT/?qs=1zthkiRbLn1IbrW0cLoSdQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF__JCJYtRxzYfMAm0tylQVAdAQUAoB7_gqtJqTJ nNsEaAm_D8P8HAQ

[[email protected]]

On Friday, January 27, 2017 at 9:58:39 PM UTC-6, Andy Blackburn wrote:
> I've concluded that this is the best solution, with one modification - each battery is connected through and ideal diode so there is no cross-charging. Unlike Schottky diodes, which have on the order of a 0.5 volt drop at typical glider panel currents, ideal diodes have only a 0.03 volt drop up to about 10 amps.
>
> 9B
>
> On Friday, January 27, 2017 at 12:38:59 PM UTC-8, Charlie M. (UH & 002 owner/pilot) wrote:
> > Nice writeup and diagrams.
> > What I, and others, do is similar to one of yours.
> > Behind the panel, there is a single "common buss" for "+" and "-" that feeds all devices. Feeding that are 2 batteries, each with their own simple on/off master switch.
> > You then have 3 modes of operation:
> > -feed everything from battery 1
> > -feed everything from battery 2
> > -feed everything from both batteries at once. There is the previously stated issue regarding batteries at different states of charge, different ages, etc.
> >
> > Plenty of our electronics can display battery voltage or add in a simple panel voltmeter to watch the "device side of the buss" to monitor battery/system voltage.
> > When voltage gets low, turn on the second battery and THEN turn off the first battery so everything remains powered.
> >
> > I like to use screw type terminal strips to make it easier to add/remove devices.
> >
> > These are nice since they've harder to short out.....
> > http://www.mouser.com/ProductDetail/TE-Connectivity/1776293-5/?qs=bdENzIhz2rlx1zfI7zIhoQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF9MgBsB6Nbc_wifpgMGJfXW1nRYf20nUY6nfHlt tzIEaApPW8P8HAQ
> >
> > These can be used with ring or fork terminals.....
> > http://www.mouser.com/ProductDetail/Eaton/KU4-00WCMT/?qs=1zthkiRbLn1IbrW0cLoSdQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF__JCJYtRxzYfMAm0tylQVAdAQUAoB7_gqtJqTJ nNsEaAm_D8P8HAQ

My (new to me) ClearNav has an excellent option for monitoring the battery in use. The voltage is displayed as soon as it drops below a level that can be set by the pilot. Now just switch to the secondary power source.
Herb

[OHM Ω http://aviation.derosaweb.net]

Charlie - Two comments on your comments.

1) These are nice since they've harder to short out.....
http://www.mouser.com/ProductDetail/TE-Connectivity/1776293-5/?qs=bdENzIhz2rlx1zfI7zIhoQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF9MgBsB6Nbc_wifpgMGJfXW1nRYf20nUY6nfHlt tzIEaApPW8P8HAQ

OHM - When I use these I crimp on "pin" terminals rather than sticking the bare wire into each hole.

2) These can be used with ring or fork terminals.....
http://www.mouser.com/ProductDetail/Eaton/KU4-00WCMT/?qs=1zthkiRbLn1IbrW0cLoSdQ%3D%3D&gclid=Cj0KEQiA_KvEBRCtzNil4-KR-LIBEiQAmgekF__JCJYtRxzYfMAm0tylQVAdAQUAoB7_gqtJqTJ nNsEaAm_D8P8HAQ

OHM - Use only ring lugs. After months of flying vibrations the screw holding the "Spade" (fork) terminals will back out slightly and the terminal will fall out.

[OHM Ω http://aviation.derosaweb.net]

Diodes - @9B - Yep. Watch out for those lost volts. Regular 1N4xxx series diodes commonly used are even worse than Schottky! And you can also loose volts by using too small of wire (14ga for the main run), or too small of breakers. Breakers? Yes, breakers. Stick with 5A breakers or larger as even 4A breakers loose 0.3V and 1A breakers are awful loosing 1.1V (Klixon spec max voltage drop)!! Who knew?

[Steve Koerner]

On Sunday, January 29, 2017 at 11:19:25 AM UTC-7, OHM Ω http://aviation.derosaweb.net wrote:
> Diodes - @9B - Yep. Watch out for those lost volts. Regular 1N4xxx series diodes commonly used are even worse than Schottky! And you can also loose volts by using too small of wire (14ga for the main run), or too small of breakers. Breakers? Yes, breakers. Stick with 5A breakers or larger as even 4A breakers loose 0.3V and 1A breakers are awful loosing 1.1V (Klixon spec max voltage drop)!! Who knew?

Most new setups use Lithium batteries these days. Lithiums do a very good job of holding voltage until the bitter end. That makes the forward drop from a Schottky combiner pretty insignificant. Agree about the low amp breakers though.

[John Carlyle]

I prefer to keep things simple, similar to Charlie M above. In my ship each battery has a 10 amp fuse and an on-off toggle switch. These toggle switches feed a single master on-off switch, which then feeds individual blade fuses for each instrument. Each instrument also has an on-off switch. Reliable, easy to control, and low voltage loss.

-John, Q3

[SF]

Any glider Wiring Diagram should show a fuse located as close as possible to the battery. I put mine right on the battery using Automotive 5A blade style weather proof fuse holders. There is a lot of energy there, and there are a lot of bad stories out there about wiring shorts, and smoke filled cockpits when fuses were not installed right on the batteries.

I recommend using the automotive blade style fuses instead of circuit breakers. I can't imagine a situation where resetting a circuit breaker in a glider panel results in anything other than a second trip. Circuit breakers have a higher voltage drop, and are a lot less reliable than fuses.

I have always run my glider Batteries in parallel on a common 12V bus, and it's never been a problem. I always buy identical batteries at the same time, and retire them at the same time. The other wiring schemes depicted will work just fine.

SF

[Charlie M. (UH & 002 owner/pilot)]

I believe everyone will agree to use a fuse close to/at each battery to give protection in case a wire is shorted somewhere along it's length, etc.
The OP (in his link) mentions this, but also indicated them being eliminated in his drawings to keep it simple.

As to a pin, ring terminal, fork terminal, soldering a boot at the open end can help with connectivity over time. Just don't wick solder up past the other end of the crimp to preclude making a stress point.

Wiring should also be fine stranded so it's flexible, solid wire can fatigue fail over time due to work hardening of copper with even minor bending.

[[email protected]]

On Friday, January 27, 2017 at 11:35:50 AM UTC-7, Andrey Lebedev wrote:
> Hello group,
>
> I did a wiring overhaul in my cockpit recently. I learned a lot in the process and decided to document my research for various ways you can connect batteries to your electronics. Hopefully this will be helpful to folks like me half a year ago.
>
> https://medium.com/taming-a-sailplane/sailplane-power-supply-479b6632fedd
>
> For my ship I've chosen scheme I call "Commuted circuits". I must admit I was pretty amazed by elegance of the solution.
>
> Any feedback, especially practical experience, is highly appreciated.
>
> --
> Andrey Lebedev
> WU

I like the redundancy of combining two batteries with individual DPDT switches. Flipping a battery selector, creates a power glitch which shuts down my computer and invalidates the trace. The Ideal diodes sound like the way to go with this arrangement. I found this (unpopulated) Ideal diode circuit board online; with parts from Mouser each board would run about $2 each.

https://github.com/xioTechnologies/Ideal-Diode

[[email protected]]

On Monday, January 30, 2017 at 8:43:45 AM UTC-5, wrote:
> On Friday, January 27, 2017 at 11:35:50 AM UTC-7, Andrey Lebedev wrote:
> > Hello group,
> >
> > I did a wiring overhaul in my cockpit recently. I learned a lot in the process and decided to document my research for various ways you can connect batteries to your electronics. Hopefully this will be helpful to folks like me half a year ago.
> >
> > https://medium.com/taming-a-sailplane/sailplane-power-supply-479b6632fedd
> >
> > For my ship I've chosen scheme I call "Commuted circuits". I must admit I was pretty amazed by elegance of the solution.
> >
> > Any feedback, especially practical experience, is highly appreciated.
> >
> > --
> > Andrey Lebedev
> > WU
>
> I like the redundancy of combining two batteries with individual DPDT switches. Flipping a battery selector, creates a power glitch which shuts down my computer and invalidates the trace. The Ideal diodes sound like the way to go with this arrangement. I found this (unpopulated) Ideal diode circuit board online; with parts from Mouser each board would run about $2 each.
>
> https://github.com/xioTechnologies/Ideal-Diode

I have used the individual switches for each battery going to the main bus for over 20 years with no negative issues. When it is time to switch I turn the new one on and then the old off. The current flow that may occur for a couple seconds, given that the voltage differential is less than 2 volts, has never caused me any problems.
I use spade connectors at the bus and have never had one loosen. It no doubt has saved a number of dropped screws into the bottom over the years. We don't have much vibration to worry about, compared to airplanes that have a full time energy to noise/vibration device.
Another experience set.
UH

[Craig Funston]

What Hank said.

Craig
7Q

[Jonathan Foster]

On Friday, January 27, 2017 at 11:35:50 AM UTC-7, Andrey Lebedev wrote:
> Hello group,
>
> I did a wiring overhaul in my cockpit recently. I learned a lot in the process and decided to document my research for various ways you can connect batteries to your electronics. Hopefully this will be helpful to folks like me half a year ago.
>
> https://medium.com/taming-a-sailplane/sailplane-power-supply-479b6632fedd
>
> For my ship I've chosen scheme I call "Commuted circuits". I must admit I was pretty amazed by elegance of the solution.
>
> Any feedback, especially practical experience, is highly appreciated.
>
> --
> Andrey Lebedev
> WU

Has anyone tried these for power distribution? Seems like a robust solution.

https://powerwerx.com/8-position-powerpole-distribution-block

[JS]

On Monday, January 30, 2017 at 3:31:32 PM UTC-8, Jonathan Foster wrote:
>
> Has anyone tried these for power distribution? Seems like a robust solution.
>
> https://powerwerx.com/8-position-powerpole-distribution-block

Not that part exactly, but have used the fused variety in about half a dozen instrument panels. They work great. I don't see the point in fuses on the panel.
https://powerwerx.com/west-mountain-radio-rigrunner-4005
Very clean, and allow you to remove an instrument and run it "on the bench" if your batteries have the same connector.
Include 15A PowerPoles by the bag (at least 25 sets), a crimp tool, and 1A, 2A and 3A fuses when you order from Powerwerx. The connectors are so easy to build that you may find yourself putting them on everything 12V.
They used to have a basic 15A connector crimp tool which worked fine. Don't see it listed any more.
Jim

[Charlie M. (UH & 002 owner/pilot)]

No, I've used what I linked earlier.
I have used powerpole connectors for battery connections in sailplanes as well as electric RC cars. I solder them in, thus I can unsolder them and change the wires if I wish at a later date. Usually get them from a hobby place like Tower Hobbies. An alternative are Deans connectors, also from a hobby place.

[2G]

On Friday, January 27, 2017 at 10:35:50 AM UTC-8, Andrey Lebedev wrote:
> Hello group,
>
> I did a wiring overhaul in my cockpit recently. I learned a lot in the process and decided to document my research for various ways you can connect batteries to your electronics. Hopefully this will be helpful to folks like me half a year ago.
>
> https://medium.com/taming-a-sailplane/sailplane-power-supply-479b6632fedd
>
> For my ship I've chosen scheme I call "Commuted circuits". I must admit I was pretty amazed by elegance of the solution.
>
> Any feedback, especially practical experience, is highly appreciated.
>
> --
> Andrey Lebedev
> WU

Here is an electronic battery isolator that solves all of the problems about voltage drop, cross battery current flow and switch-over glitches:

http://www.powerstream.com/DC-UPS-1212.htm

Disclaimer: I have not used this device

Tom

[[email protected]]

Another simple solution is to choose between the batteries with a simple SPDT switch, but bypass each arm with a (non-ideal) diode (regular silicon, or Schottkey). That way, (1) there is no voltage drop on the line from the battery that is chosen by the switch, (2) there is never any current flowing from one battery into the other, and (3) if you are too busy flying to notice that your chosen battery has run down, and thus fail to switch to the other battery, everything will keep running from the second battery anyway, albeit with a drop of about 0.7 volt or less (which is OK while that battery is still strong).

Disclaimer: in my glider I use a single battery, and in the rare cases where its voltage gets low, I turn off non-essential equipment (and stop yakking on the radio :-)

[[email protected]]

PS: forgot: (4) there is only a small voltage glitch when the switch is flipped.

[SF]

For power distribution I used an industrial terminal strip with a mini blade type fuse between each side. SO the 12V bus is on one side and all the connections are fused on the other side. Not exactly airplane stuff, but they are routinely used in machinery with a lot more vibration & hours than a glider normally sees.

SF

[John Wells]

I just redid my panel and have used individual three-way on-off-on toggle switches together with a DIY MOSFET circuit to enable switching each instrument between battery A or B in flight.

The circuit itself needs a few components (2 N-channel MOSFETs, 2 capacitors and 4 resistors per channel) to facilitate switching in-flight without dropout, but they're all surface mount and the overall circuit isn't much bigger than the simple bus bar it replaced:

http://i.imgur.com/gGsPTU2.jpg

The benefit over running everything off a single battery at a time is that each battery should hold up better with the lower current required from each individual battery, but on a long flight I could separate "priority" and "nice to have" instruments onto separate batteries if power gets low, and I don't need to decide what the configuration might be in advance.

The capacitors on the MOSFET gates give about 2-3 seconds switching time when toggling from battery A to B or vice versa through the "off" position, ensuring flight loggers etc continue to work.

I've also added a simple "always on" channel with a couple of diodes for the gear up warning.

[krasw]

I didn't even know it was possible to have so many complicated solutions to simple problem. My battery1/battery2 toggle switch is clearly from stoneage.

[JS]

On Thursday, February 2, 2017 at 12:38:26 PM UTC-8, krasw wrote:
> I didn't even know it was possible to have so many complicated solutions to simple problem. My battery1/battery2 toggle switch is clearly from stoneage.

Moi aussi.
Jim

[[email protected]]

Re working my DG 400 electrical system. Adding 2 batteries for instruments only and keeping main batts for ships power only.

I have pulled all of the positive wires off everything that is not motor related. At present there is one main ground buss.

Some of the instruments already have breakers and positive wires from the breaker to the instrument and negative to the ground buss.

Would I create any problem using this common ground buss for the instruments already on it as well as the new instruments. All instruments will be supplied by two LiFePo4 batts. The ships chemistry is lead acid and with my current plan they would both share the same ground buss.

I will be using two separate switches for the new batteries that are pull to unlock SPST.

Thanks

Kevin
92