Laptop Usage

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Monty

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New to forum and appreciate any and all advice. We now have a 21 foot MH which will be a test bed for future travel plans - not full time but larger and nicer for extensive use. I have been able to get a handle on most things but, as usual, understanding electrical on my weak side. My question is laptop usage. We will not have, althought it would be nice, any mobile net capabality - at least not yet. In the interim I shall be dependent on various hot spots for wi-fi usage. The lap top is 6.3 amps and as I understand it one needs to multiply by 110-120 volts for watts. But I just can't believe the laptop is about 700 watts! Is there a built in transformer which will allow me to use an inverter in the 400 watt range - - I need to use on the road as I have a lot of misc data to imput. My apologies for the ignorance but this sort of thing drives me nuts.? Tom M.........? ? ?
 

Tom

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I doubt your laptop consumes 6.3 Amps at 110 Volts. The laptop I typing on is a power hog and its power supply is rated at only 90 watts. I suspect the 6.3 amps is at 15 volts or whatever the input voltage of the computer is. Check the values on the power supply (mine is stated as 4.7 amps at 19 volts). The current drawn at 110 volts is less than an amp, although the label actually says 2 amps.
 

Carl L

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But I just can't believe the laptop is about 700 watts! Is there a built in transformer which will allow me to use an inverter in the 400 watt range - - I need to use on the road as I have a lot of misc data to imput. My apologies for the ignorance but this sort of thing drives me nuts.

Why do the inverter thing when you can just get a car/truck adapter for your laptop and use the 12VDC outlets that tap on to your house battery(s).  That rascal has a lot of amp-hours to devote to powering your laptop.
 

Tom

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Oops, didn't answer the inverter question. There are inexpensive inverters that plug into a cigarette adapter. In addition to several el cheapo brands, I have one rated at 140 watts continuous and  made by Xantrex. It powers this laptop with power to spare.

BTW here's the small Xantrex I'm talking about. I have some of the bulkier 400W ones, but rarely need them for anything.
 

Karl

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If your only concern is for the laptop, do what Carl said - get a cigarette lghter plug for it. On the other hand, an inverter, even a small one, might come in handy for a SMALL tv set or other 110V appliances like a light fixture. Don't expect it to run some devices like electric clocks, for example, because they rely on a pure sine wave to keep correct time and those small invertors put out a modified siine wave, not a pure sine wave. If you go the inverter route, get one that's around 300-400 watts so you can run a few low-current devices simultaneously.
 

John From Detroit

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Commodore said:
The lap top is 6.3 amps and as I understand it one needs to multiply by 110-120 volts for watts. But I just can't believe the laptop is about 700 watts! Is there a built in transformer which will allow me to use an inverter in the 400 watt range - - I need to use on the road as I have a lot of misc data to imput. My apologies for the ignorance but this sort of thing drives me nuts.  Tom M.........     

Generally a Laptop is less than 100 watts operating though the power supply may be rated well over the power requirement of the laptop itself, also the power ratings stated are PEAK power, not operating power, Peak means you are turing the computer on with a dead battery just after plugging it in.

Other than that Xantrex Prosines are among the finest inverters made, true SINE WAVE, very computer friendsly, and come in power ratings well over 700 watts, Mine is a 2,000 watt unit

I say they are AMONG the finest because there are other true sine-wave inverters out there and I suspect that many of them will be very competive with the Prosine, some may well be better
 

Karl

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Just to keep apples and oranges in their respective boxes, PEAK power is the highest voltage level produced by a sine wave, which is 1.414 times the true or RMS (Root Means Square) power of the wave or, inversely, RMS is .707 the Peak voltage. The Maximum power is the most current (or wattage) that the power supply will draw when it's outputs are loaded to the max. In computers, that's usually the point when power is first turned on, power is applied to the motherboard, processor, and peripherals, and the disk drive(s) start turning. While desktop or tower computers may well need a 200 - 300 watt power supply, most laptops require much less power to operate. That 6.3 amps you mentioned is, in all probability, at 12-15 Volts; or about 64-90 watts.

Next, pure sine wave inverters vs. modified sine wave inverters: Most, repeat most appliances will operate properly using a modified sine wave. My microwave oven does not. Electric blankets with electronic controls do not. Clocks do not. SOME computers do not. There's no way to tell until you try it out. Almost any purely resistive devices like incandescent lamps, toasters, electric heaters will operate fine. Should you opt for a pure sine wave inverter instead? Given the current use of electronic controls and small yet efficient switching power supplies being used in many modern appliances, I would go with the pure sine wave over the modified. However, a like-size pure sine wave inverter - say a 2kW unit, will cost about double that of it's modified sine wave cousin. Because I already have a modified sine wave inverter installed, I can't cost justify replacing it with a new one just for those few things that don't operate properly. I've modified my electric blanket control to be happy with it, and use my generator when I want to use the microwave (assuming I'm not on shore power) If you're doing a new install, then definitely go with a pure sine wave unit. Just my humble opinion; others may not feel the same way.
 

John From Detroit

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Thanks for the Peak/Max power clairification.  I missed the voltage mentioned in the earlier post too

With a laptop maximum power also involves re-charging the battery.

I have a over-size power supply for my Thinkpad R-31 (1.xGHZ CPU, 256 Meg Ram, 80Gig HD) and it is still only 100 watts max (the power supply, the laptop only takes what it needs)

And the reasons you cited were primary factors in my choice of a Prosine over a modified sine wave inverter (which I already had "in stock" though not "installed")  I felt the Prosine was worth the added cost, again, for exactly the reasons you posted

It can and does run the microwave, the Forward (and rearward) entainerment centers and one additional outlet whivh will be where I plug in the computer when running on 120... Normally in the MH the computer runs on whatever is handy 12v or 120v only difference is which brick pluggs into the wall
 

Monty

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Great response(s) and much, much appreciation to all. I checked the laptop once again and it is 6.3 at 19 volts so my small inverter should handle just fine - - certainly hope so. Tom M. 
 

John From Detroit

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Commodore said:
Great response(s) and much, much appreciation to all. I checked the laptop once again and it is 6.3 at 19 volts so my small inverter should handle just fine - - certainly hope so. Tom M.? ?

6.3 at 19 volts rounds to 120 watts, Just remember that is the turn on requirement with a dead battery, and overhead (The actual power requirement is likely less than that, most computer builders overbuild the power supply slightly), and of course if you let the battery charge BEFORE you turn on the laptop the power useage goes down.

also the laptop will draw battery power if it needs to while booting

Once booted the power requirements drop a bit too.... I've had occasions when I plugged the "Brick" into my inverter, but not the computer, (This is a high load point too) then booted the computer on its internal battery, then plugged the brick into the computer... any other procedure popped the safety shut down on the inverter.

I've since gotten a better inverter (3 of them in fact)
 

John From Detroit

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Karl said:
John,

It must have been a pretty small inverter; like one of those that will handle an electric razor and not much more - similar to ac outlets in bathrooms of many Canadian hotels/motels. :p

The battery charge level was the issue
 

valleygeocacher

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For years, I've used a 70-watt, cigarette-pack sized inverter in the Tow Vehicle to keep my laptop (with a defective battery) working.

I can assure you that 110VAC current required by your laptop will NEVER exceed 100 milliamps -- 1/10Amp. You can confirm these numbers by using a Low-Current clamp-on Ammeter on ONE ONLY of the incoming power supply wires. Ask your electrician friend to do it for you.
 

Jeff

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I am not sure why but on the trip to Maine this summer my airline type power supply for my Dell could not keep the battery charged. (I think it is related to the USB GPS receiver I keep hooked up when traveling that draws its power from the laptop.

I started trying different laptop power supplies and cigarette type inverters from Best Buys from Illinois to Massachusetts trying to find one that did not overload or allow the Dell's battery to discharge over a couple of hours.  Thank goodness for BB's return policy! I have two bricks and two batteries that I tried in different combinations with no luck. I now run with the coach inverter on supplying 110 power to the Dell's brick.
 

Tom

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valleygeocacher said:
I can assure you that 110VAC current required by your laptop will NEVER exceed 100 milliamps -- 1/10Amp.

That wouldn't work for my 90W notebook power supply.
 

Ned

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I can assure you that that the 110VAC current required by your laptop will ALWAYS exceed 100 milliamps if it's plugged in.? My Toshiba has a 120W power supply.
 

BruceinFL

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Jeff /Washington said:
I am not sure why but on the trip to Maine this summer my airline type power supply for my Dell could not keep the battery charged. (I think it is related to the USB GPS receiver I keep hooked up when traveling that draws its power from the laptop.

I started trying different laptop power supplies and cigarette type inverters from Best Buys from Illinois to Massachusetts trying to find one that did not overload or allow the Dell's battery to discharge over a couple of hours.  Thank goodness for BB's return policy! I have two bricks and two batteries that I tried in different combinations with no luck. I now run with the coach inverter on supplying 110 power to the Dell's brick.

Jeff,
I use the iGo auto/air power adapter all the time to run my Dell laptop with a USB GPS and never have a problem. Maybe something is wrong with your power adapter. If not, perhaps you can go into the laptop's software and make sure the unused periphials like CD/DVD are not powered fulltime to reduce the power requirement. Or, you might have a bad battery.
 

Jeff

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Bruce:

I assumed the power supply was bad so tried three new onws, same result. Also switched to a brand new battery. ??? ???
 

Karl

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Jeff,

You say your GPS is always plugged in. Is it self-powered (e.g. has it's own p.s.) or is it getting power from the laptop USB port? If the latter, you could conceivably be drawing up to 500mA from that port which may or may not be hogging most of the laptop's ability to maintain the charge of the battery. If possible, power your GPS separately from a cigar lighter adapter or whatever else it will allow you to use. What is the maximum output rating of the laptop power supply? Does it get unusually warm in operation? You could try paralleling the two bricks to increase the maximum available power.

Bruce, good suggestion, but I don't believe the CD/DVD drive is configureable in the power settings. Without a disk inserted, current draw is minimal. It does, however, bring up another good point: If Jeff is using the GPS software directly from the CD/DVD all the time, that WOULD or COULD be a factor, and I would suggest copying the contents of the CD/DVD to the hard drive and using it from there. Jeff, you'd have to remove the software from the laptop, copy the entire contents of the CD/DVD to the hard drive, then do a re-install using the "setup.exe" (or whatever the file is called) from the directory where you copied your CD/DVD into. After all, your hard drive is running most of the time anyway, so there shouldn't be much more overhead in terms of power usage except for additional disk seeks. Maybe worth a try. 
 

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