Power from your automobile's standard plug in

Make sure you have some extra fuses along. Several years ago, I used a power inverter to plug in a laptop (using it for navigation with Delorme Street Atlas) along with a USB charger for an iPod. It worked fine on our 3000 mile trip, but it did blow the 15 amp fuse a couple of times when the laptop was drawing extra power.

A fuse in the inverter, or one of the car's fuses?

I have a switched 12v for the lighter and a "hot" 12v receptacle. They each use a 20amp fuse. At home I use a 115 to 12v convertor rated at 1 amp. It powers two GPS devices easily.
My old laptop needs 12v 3.68 amps.

Power can be estimated by multiplying the current (amps) by voltage. Assuming a 12v source and a 1/2 amp current draw, that's 6W for your Nuvi. You can figure out the draw for the video players by knowing either the wattage or the amount of current needed. Devices that run off a USB port won't draw more than a 1/2A.

Won't have that info until halfway into the first trip.

all that I would be teaching class in a school.

Word.

You can probably get a good idea of the amps available through your accessory outlet by checking the fuse powering it. My Viair 70P air compressor draws 14 amps and works fine from the accessory outlet of my BMW but blew fuses quickly in my son's Mazda. My guess is his outlet is only 10A while the bimmer is 15A. With DC, volts times amps = watts so if you know the watts needed and the amps available it is pretty easy to see if there will be enough power.

Jim

I have a Wagan "cup holder" splitter with two 12V outlets and two USB power ports. It has a 10A fuse in the plug. From what I've seen that seems to be pretty standard for splitters that plug into the cigarette lighter socket.

Of course, if the DVD players run on battery and only have AC adapters then you'll need an inverter and a power bar. A comment on that: One day I plugged a surge-protected power bar into my 600W inverter and nothing that I plugged in to the power bar would work, but the individual devices would work when I plugged them directly into the inverter. I verified that the power bar worked when plugged into house current. It seems that the surge protector was blocking the non-sinusoidal power from the (inexpensive) inverter. When I switched to a "dumb" power bar everything worked fine.

All devices have the standard "cigarette lighter" type of plugin.

What year make and model of car Dave?

01 Honda Accord Sedan, 6cyl

It was the car fuse for the cig. lighter.

I, too, have had similar concerns over the years. I have a Chevrolet Silverado C10 that has a cigarette lighter and two power ports. Each power port is lsited at 20 amps.

I also have a Honda Accord. The power port in front is listed at 10 amps.

As far as the various USB devices, it would be a good idea to check it out before you go. I remember taking the family to Branson MO a couple of years back. I brought a Slacker Radio with and connected it with a 12 volt to 5 volt USB power cord. The Slacker Radio stopped playing hours later in Kansas City. I assumed that since it was plugged in it was charging. As it turned out the cord I had only provided 500 milliamps, but the radio needs 1 amp! Just because it has a USB connector doesn't mean the cord will provide enought current to charge a particular device.

http://www.scosche.com/consumer-tech/product/2207 Scosche, and others, now have some devices that provide 2.1 amps, or more.

Dave, according to page 319 of the 2001 Honda Accord Owner manual the fuse for the Radio/Cigarette lighter is a 20 Amp fuse. It's fuse No. 9 on the Passenger side fuse panel. Remember the amount of current a radio draws is a function of volume, so the louder the radio the more power is required P(Watts)= E(volts) times I(amps). That's about a normal rating for a lighter fuse.

Here's the page reference URL.

http://techinfo.honda.com/rjanisis/pubs/om/AC0101/AC0101O003...

Thanks Prof!

They should read a book - it's more educational, and you won't have to worry about blowing a fuse!

I WISH!

The traditional "cigarette lighter" is nothing more than an electrical heating element -- and one that draws a relatively large amount of power for a short period of time. That's why those circuits have 10, 15, or 20 amp fuses on them. These circuits have been hijacked to serve far different purposes in most vehicles.

Most consumer entertainment stuff, such as DVD players, our GPS Nav goodies, cell phone chargers and stands, stuff like that, is 1 amp or so each. So you could put quite a few of them together before you hit that 10 to 20 amp limit.

We know that the large print giveth, and the fine print taketh away...

Some cars have switched accessory outlets, some have unswitched accessory outlets, and some have a mix of both.

Switched simply means the gadget plugged in thereto turns on and off with the engine of your car. Engine off, gadget off. Engine on, gadget on. I have my GPS and my radar detector on a switched circuit.

Now entering the discussion is Murphy, the Patron Saint of (bad) engineering and unintended consequences. Murphy says that when something fails, it will do so at the worst time and/or in the worst way. Murphy also guarantees that when a system is designed to be "foolproof," a better fool WILL emerge.

Gotcha #1 -- putting a lot of gadgets on an UNswitched outlet can run your battery down when the engine is off, and Murphy says that will happen quicker than you'd believe possible, and in the worst possible circumstance. When in doubt, unplug things at the end of the day/when everyone gets out of the vehicle. That "Lion King" DVD set on infinite repeat may be good for the kids in the back, but your battery will NOT forgive you.

Those "cigarette lighter" jacks aren't what engineers consider high reliability... They wiggle and bounce, and may not want to keep seated, particularly for long periods of time, bumpy roads, little ones kicking the wires or trying to use them to garotte their siblings.

Remember what these outlets were designed for? A simple (resistive) heater. So what if the circuit is broken for a few milliseconds when you hit a bump? That doesn't matter to the heating element, which is off the vast majority of the time, and if it did bounce while it was on a heating cycle, so what?

Gotcha #2 -- those brief intermittent circuit openings will usually make devices such as DVD players reset or reboot. Charging circuitry for a mobile phone or laptop isn't going to matter -- so what if the charging current gets interrupted for a few milliseconds and returns. But that DVD player will probably reset/reboot, greatly upsetting the (usually young) viewer in the back seat. Once again, Murphy says this will happen when the results will be the worst. "Daddy! It did it again! WAAAAAA!!!!!" as Daddy is trying to decide which lane to be in in the face of confusing signs and a plurality of voices telling him to do different things all at once...

Please DO NOT respond to such incidents by wrapping your nightmare of accessory splitters and plugs (or spouse and/or offspring) with tape. You will have some kind of failure where you really, really want to disconnect something right now really quickly, such as when the wire going to something STARTS SMOKING.

Either live with the possibility/probability of the occasional interruption, or talk to a local mobile sound installer, or a local mobile ham radio operator, who can help you get things wired into your vehicle in a more stable and safe manner.

A lot of the mobile crowd use connectors called Power Poles that are easy to work with, safe, and reliable.

And yeah, rental cars can be a pain...

But remember the difference between a four wheel drive vehicle like a Jeep and a rental car -- there are some places you can't get to in a Jeep...

Drive safe -- remember the other threads on this forum about avoiding distractions.

And happy Father's Day for all those dads, all those hours driving while being kicked by a young one in the back seat, listening to "ARE WE THERE YET?," "TELL BILLY TO STOP LOOKING AT ME," and our favorite, "I NEED TO PEE NOW!"

Thanks for information on the power outlets.
I never thought of that, this may very well be the culprit when people complain of reboots believing it's the GPS at fault.

That would only be true if the GPS had no battery or the battery was completely dead.

Almost every electronic device will list on it's label how much current, in amps, it needs. Add all of the current draws together and you will have the size fuse you will need. Don't worry about watts or any other measurement. Fuses are rated in amps, not watts.

Since our society has gotten all 'big brother', all of the latest cigar lighters are de-rated. They no longer need to supply 15 or 20 amps to a heating element so car manufactures have reduced the size of the wire feeding them. This means that they are fused, in some cases, as low as 10 amps. Get your owners manual out and find out what size fuse they used. Remember that there needs to be a fudge factor in fuse size. It really isn't a good idea to try to draw 10 amps through a 10 amp fuse. You need at least a 50% fudge on fuse size. If your load is 10 amps then your fuse size should be 15 amps.

If the power adapter has a 10 amp fuse on it, and you are running 10 amps, DO NOT increase the fuse size. The fuse rating is there due to wire size as jackj180 mentioned. Increasing the fuse and running maximum amps will cause the wire to heat up. It will possibly melt and cause a fire. Do you remember the "I didn't have a fuse so I stuck a penny (tin foil) in the holder"?

Trip was better than I expected. Girl did not have a device that needed power. Read a book the entire trip!

Wife forgot headphone to her DVD player so decided not to use it.

Only grandson and I needed power.

Thanks to everyone for their teaching.

Good info in this thread.