Hand held appliance voltages
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weirdjim
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Tom-D
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Thanks Jim.
kgruber
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Tom-D
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A lighter element draws almost that much
Olsen0353
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Do you have an ampere meter to monitor system draw?
Tom-D
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Yes, but I don't have a bunch of stuff to plug in to take a reading.
Geico266
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3-5 amps is what we use when building EAB, BUT if you are going to leave it hot (direct to the battery) for a battery charger connection you might want to leave it at 10 amps.
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Tom-D
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It's wired thru the master, but not one of the circuit breakers. It will have its own fuse. thus the question. I think I'll put a 2 amp in it to start that should carry a GPS or hand held radio.
The fuse should be rated to the wire or fixture limitation, not appliance requirement.
Tom-D
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Then I could put a 100 watter in it, that would really help …. right?
weirdjim
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Please don't. Part 23 allows UP TO 5 amps to be drawn directly from the battery without going through the master only if the fuse/breaker is located immediately adjacent to the battery.
Jim
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100 watt what? You mean 100 amp? You've gotten everything so confused here starting with the title. The appliance voltage is Pre determined and one uses what voltage is supplied. Different appliances are rated in Watts determined by how much electricity they use. How many amps that will be is figure by the formula Volts * Amps = Watts which is worked Watts/Volts=Amps. Fuses are rated in Amps, not Watts. If you have a 12v Source and a 100 Watt requirement you would need 8.33 amps, so best to use a 10 amp fuse. If the wiring and fixture are able to handle 100 amps, then you could put a 100amp fuse in it and the appliance will still only draw 8.3 amps.
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Tom-D
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Don't get off on a rant, I know how to do the volts/amps formula.
I doubt the fixture is rated for more than 30 amps. I don't know what the wire gauge or length is, the combination will determine how many amps it can handle.
Tom-D
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I also know how to do the graph given in the 43.13 to figure the wire size.
but in both cases you must know the numbers to plug in.
Do you plan to plug in a GPS, use the cigarette lighter, or plug in an electric heater? I think the limiting factor will be the socket fixture, typically they are 30amp if designed for a lighter. If it's designed as a power point I've seen them in 10 & 15 amp ratings. The fixture should be stamped.
Tom-D
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You can only plug in one device at a time, and nothing I have will require more than a 2 amp fuse. My old GPS rated draw is in milli amps, so I think a 2 amp will do.
any one know of a device that will draw more than 2 amps ? How much does the new phones draw while charging?
iPad charger ?
Tom-D
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Did you forget, I'm building 34V ? the old OEM fixture is gone, the wire to it was a # 10. We will no longer use it as a high draw heater element type for which it was designed.
If some one rolls a seat roller over one of those flimsy power chords typically found on a GPS or hand held radio, I don't want this to become a welder or burn off the chord.
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Go with whatever the fixture you replace it with is rated for. The 30a fixture is available at any auto parts store on the HELP display. You might also consider putting in a USB bar as well to directly plug in iPads, phones, and so forth without need of an adaptor.
Tom-D
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30 amp rating is a maximum I certainly do not want anything near that. I'm not going to try to jump start the engine from this, I'm only running low voltage hand held devices. And would like to minimize the damage as much as possible. If the circuit board in one of these devisees decides to self district I don't want it to turn into a road flare.
Typically an external fuse won't prevent that which is why the plug in method is nice, just pull the plug. Much of the internal componentry is of such small size it will not be protected by the source fuse. Most things are internally fused, especially with the lighter style power points, they contain the fuse inside the point itself in the tip. The primary source fuse to the receptacle is there to protect the lead in wire and fixture, fuse for it since you don't know what future owners will want to plug in. Besides, shouldn't it be rated to what was removed?
Tom-D
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no...
jesse
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My Flybaby has a 1 amp which is way too small. If I'm charging my iPad I'll pop it everytime I transmit on my radio.
5 amp would do everything you'd want to do with electronics, more or less, but if you can size it higher it may be worth doing. Generally you would choose breaker size for something like this based on what the wire feeding it can provide.
5 amp would do everything you'd want to do with electronics, more or less, but if you can size it higher it may be worth doing. Generally you would choose breaker size for something like this based on what the wire feeding it can provide.
jesse
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Any respectable device is going to have it's own form of fuses to handle an internal short. Damage to modern electronics via internal shorts can happen with very few amps - you're not going to be able to prevent that.
Tom-D
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I know that, the intention is to protect the chord to the device. Twice I have seen these chords frayed due to the seat rails in a Cessna.
jesse
Touchdown! Greaser!
In every device I own there is a fuse before the chord running to the device (inside the plug).
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3393RP
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Tom, a direct short to ground like are describing will blow any rated fuse that will fit in a typical inline holder. I would use a 10 amp so it could power the odd larger load, like a hand held light for instance. That's a personal preference, of course.
But do whatever you're comfortable with, I know you have a little experience. :wink2:
denverpilot
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Most automotive applications are 10A for in-rush current and/or that old cigar lighter heating element. Just adding to the info pile. Doesn't really apply to aviation, I know... But you could check your car...
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Your thread title says "appliance voltages". Devices that you will plug into a lighter power socket will be 12 volt devices. In the quote above you said you are building a 34 volt system and the lighter socket will be wired off of the master switch. You have me scratching my head here since the airplane electrical systems I'm familar with are either 12 or 24 volts. I have to ask the question why you would be putting in a 34 volt system in your plane? Plus it would really be 39.6 volts(18 cells x 2.2 volts per cell). Simply put, you will NOT be able to plug up any handheld devices to your system if your socket is wired for 39.6 volts since they are expecting 12volts regardless of what size fuse you use. What about the rest of your avionics? They will be expecting either 12 or 24 volts too. We need more information about your system to be able to help you.
34V is a tail number, not voltage. Many electronics will accept 9-36 Volts.
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Go back with 10 amp. Insure the wire leading to the lighter socket is up to correct gauge. I've used the socket for a spotting light before, and it draws about 5 amps(60Watt lamp).
The lighter socket is rated for 10 amps for a short duty cycle of about a minute, to heat the lighter element. Stick with the original amperage and you can't go wrong. If there is a dead short on a wire being served by the socket, the wire will either fry due to it's small gauge, or if it supports the 10 amp load, it will pop the fuse.
The lighter socket is rated for 10 amps for a short duty cycle of about a minute, to heat the lighter element. Stick with the original amperage and you can't go wrong. If there is a dead short on a wire being served by the socket, the wire will either fry due to it's small gauge, or if it supports the 10 amp load, it will pop the fuse.
MickYoumans
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Sorry for my mistake about the 34v. It had me shaking me head. This thread has seemed like such a train wreck that I was really wondering.
The main concept to understand is that the fuse for the socket is for protecting the electrical system of the airplane, not any devices plugged into the socket. The fuse in your plug shown in post 31 above is for protecting your device. The amp rating for the socket fuse should be smaller than the design amperage of the socket and less than the current capacity of the wire size used to wire it. You seem to be hung up about protecting against damage to the power cord plugged into the socket. Regardless of what size fuse is used, if a short circuit condition occurs due to a damaged cable allowing the two wires to touch, the fuse will blow immediately due to the excessive current draw. The fuses are sized in devices like your GPS to blow if current draw within the device exceeds an amount determined by the manufacturer to be abnormal. Since the GPS fuse will be a lower amp rating than the socket fuse, it is the one you would expect to blow first although it would be possible for both to blow.
I don't think Henning was going off on a rant toward you. It sounded to me like he was trying to provide you with good solid information that seemed to be lacking prior to his post.
The main concept to understand is that the fuse for the socket is for protecting the electrical system of the airplane, not any devices plugged into the socket. The fuse in your plug shown in post 31 above is for protecting your device. The amp rating for the socket fuse should be smaller than the design amperage of the socket and less than the current capacity of the wire size used to wire it. You seem to be hung up about protecting against damage to the power cord plugged into the socket. Regardless of what size fuse is used, if a short circuit condition occurs due to a damaged cable allowing the two wires to touch, the fuse will blow immediately due to the excessive current draw. The fuses are sized in devices like your GPS to blow if current draw within the device exceeds an amount determined by the manufacturer to be abnormal. Since the GPS fuse will be a lower amp rating than the socket fuse, it is the one you would expect to blow first although it would be possible for both to blow.
I don't think Henning was going off on a rant toward you. It sounded to me like he was trying to provide you with good solid information that seemed to be lacking prior to his post.
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jesse
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What he said.
kgruber
Final Approach
Light aircraft electrical systems are mostly 14V and 28V. Only the batteries are 12V and 24V.
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Agreed. The alternator/voltage regulator output has to be greater than the battery voltage for the alternator to carry the load and provide charging current for the battery while the plane is in operation. Using a 12 volt battery for an example, a new fully charged battery is really 13.2 volts (6 cells x 2.2 volts per cell). The alternator/voltage regulator has to be greater than this 13.2 volts in order supply the current to the electrical loads in the plane instead of the battery doing it. The difference in voltage between the alternator output and the battery provides a small charging current to the battery. Hence the 14v system. The 12v/14v designations are used interchangeably since they are both refering to the same system.
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