Usb charger for 28v system

[r0ckst4r]

I was looking at a USB charger for the "cigarette lighter" socket in the M20R.  I know its a 28v system and commonly available usb adapters say they are 24v compatible.  I'm just wondering the importance of those extra 4 volts.  Am I over thinking this or am I setting myself up for an electrical fire?

[KSMooniac]

You might check your POH, but I believe the socket is 12V.  (I'm flying an old 12V plane, so don't take my word for it!)

Make sure you get a good one that won't cause interference with the radios or GPS.  Or consider a real permanently installed version...

[r0ckst4r]

17 minutes ago, KSMooniac said:

You might check your POH, but I believe the socket is 12V.  (I'm flying an old 12V plane, so don't take my word for it!)

Make sure you get a good one that won't cause interference with the radios or GPS.  Or consider a real permanently installed version...

I was actually thinking about that myself as well as there are a few things on the plane the for some reason do convert the voltage to 12v.   I'll give it a test when I head to the hangar again and report unless someone chimes in first with an answer. 

[GeeBee]

It was 12 volt on my Ovation. There is a stepper.

[PT20J]

My 1994 M20J was 28V at the cigar lighter. 

The battery is about 24V, the alternator puts out about 28V. Some stuff is labelled 24V; some 28V. It's the same thing -- just how you look at it. So something labelled 24V or 28V will work, assuming that the lighter is not stepped down to 12V as apparently some are. Just get a multimeter and measure it.

[r0ckst4r]

I just happened to have a scanned copy of my POH and I'll be damned, it's 28V at the cigar lighter.  They even specifically warn you.  I'm still going to test this out when I get to the hangar.

[KSMooniac]

That is surprising to me... The universe of devices that run on 28V cigarette lighter plugs has got to be very small!

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[Slick Nick]

Cigarette lighters are 14V, Cigar lighters are 28V.

[r0ckst4r]

So here is the voltmeter result.  Sure enough, it gets about 24V at the socket.  (engine off)

Edited December 3 by r0ckst4r
Specify engine off

[LANCECASPER]

13 hours ago, r0ckst4r said:

I just happened to have a scanned copy of my POH and I'll be damned, it's 28V at the cigar lighter.  They even specifically warn you.  I'm still going to test this out when I get to the hangar.

It depends on the serial number of your Ovation. Later Ovations, Bravos and all Acclaims had a converter mounted on the back of the baggage bulkhead to convert from 28 to 14 volts, along with a circuit breaker back there. 

[hypertech]

You could call the manufacturer of the charger you want to use, but anything labeled 24V should be fine.  A "12V" system charges at 14ish volts and a 24V system charges at 28ish volts.  Things labeled for use on 12/24V systems would typically be able accept more than the expected charging values.  A 12/24V rating in marketing materials is not necessarily a tech spec for maximum input voltage.

[Aerodon]

Cessna typically installed a honking great resistor in line with the cigar lighter.  That works when you use a 5A device, but not a 0.5A device.  I installed a voltage converter where the avionics cooling fan used to be so I can properly use 12/14V devices like tire air compressor, mattress inflater, fuel pump etc.  And the occasional USB or other device that really needs 14V.

Search for Lonestar voltage converters.  Or KGS LT-71.  

I have this KGS 4A  that I would sell, but they are not inexpensive.

Cessna put the Astron N2412-12 in their 28V planes - quite affordable but a little big and heavy.

Aerodon

 

[FlyingDude]

6 hours ago, Slick Nick said:

Cigarette lighters are 14V, Cigar lighters are 28V.

I've always wondered why cigars have to be bigger than cigarettes! Because 2x voltage!

[Pinecone]

20 hours ago, Aerodon said:

Cessna put the Astron N2412-12 in their 28V planes - quite affordable but a little big and heavy.

Aerodon

 

Astron makes boat anchors.

But they LAST.  The one in my ham shack has been on for over 30 years.

 

[Ed de C.]

For my M20R I bought the cigarette lighter adaptor sold by Mountain High Oxygen systems.  Idea was to power the EDS modules and MH said the quality mattered.  The unit is probably overkill at $55, but it works fine.  I'll note that at night, the voltage display is too bright, so I yank it out.  I think I have a cheap adaptor kicking around from my wife's car that also worked fine to power an i-phone.  Mostly, it's my i-pad that needs power mid-flight and I plug that into my portable battery in the pocket by my left knee.

Ed

[LANCECASPER]

11 hours ago, Ed de C. said:

For my M20R I bought the cigarette lighter adaptor sold by Mountain High Oxygen systems.  Idea was to power the EDS modules and MH said the quality mattered.  The unit is probably overkill at $55, but it works fine.  I'll note that at night, the voltage display is too bright, so I yank it out.  I think I have a cheap adaptor kicking around from my wife's car that also worked fine to power an i-phone.  Mostly, it's my i-pad that needs power mid-flight and I plug that into my portable battery in the pocket by my left knee.

Ed

Anker makes good USB adapters that accept from 12-24 volts. https://www.amazon.com/s?k=anker+535+car+charger&crid=27XSFUPZC1XWI&sprefix=anker+535%2Caps%2C173&ref=nb_sb_ss_ts-doa-p_2_9

The other cheap ones can cause interference with radios. 

[N201MKTurbo]

Just go to a truck stop, they usually have a good selection of USB adapters that work on 28V. If you get radio interference, go get a different one.

[Ragsf15e]

21 minutes ago, N201MKTurbo said:

Just go to a truck stop, they usually have a good selection of USB adapters that work on 28V. If you get radio interference, go get a different one.

And, truck stops can be fun!  You never know what you’ll see, hear, or smell there!

[N201MKTurbo]

1 hour ago, Ragsf15e said:

And, truck stops can be fun!  You never know what you’ll see, hear, or smell there!

And the best selection of beef jerky ever!

[Pinecone]

Another thumbs up for Anker adapters.  And cables.

[glenn reynolds]

I have installed four USB adapters,  the first two are 1 amp output which is too low for an Ipad.  the next two were 2 amp units which the iPad likes.  I got them all on Amazon and they are wired in series with my 24 volt cig lighter that way they are fused.  they have worked great with no issues.  I did use the better quality aviation wire of the correct size so my mechanic was okay with my work.  if you put 24 volt in your search engine you should get a couple USB units which will take that input. 

[kortopates]

Be careful not all USB adapters will work without causing interference noise on the radio. You are looking for one okay for 12/24V. I can’t recall the brand i use which fits in the hole flush but if you use Google to search older threads on MS for 24v USB adapters you’ll find at least one thread that mentions a popular brand that has been shown not to cause interference noise.


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[glenn reynolds]

Good information.  I tested mine after purchase, but before permanently mounting it and had no difference.  I wired it temporarily to the lighter circuit and then pulled and reset the breaker while flying with all the avionics on and functioning including shooting an ILS.  I got zero change and so permanently installed them.  My mechanic said it would have been simpler to use an oscilloscope, but I don't own one and besides it was more fun flying the test.