dunpeal Posted November 2, 2012 Share Posted November 2, 2012 Hi, I recently bought a 1990 toyota Itasca with stock electric setup in the coach. I am trying to power a 210watt 10amp laptop using a group 27 deep cycle battery. How do i do this ? I bought a 100-500watt black and decker inverter but it will not give enough power from the cigarette lighter connection. Are 12volt cigarette port connections not powerful enough to run this ? what is the most cost effective route to power my laptop ? thanks!! so glad these forums exist! inverter http://www.homedepot...r&storeId=10051 the product description states Also includes a 100-watt DC plug and a 500-watt battery clip for use in automobiles as a 100-watt output or hooked directly to a battery for a full 500-watt output this sounds like I have to take the coach battery out to use the full 500watts? Quote Link to comment Share on other sites More sharing options...
linda s Posted November 2, 2012 Share Posted November 2, 2012 Gotta wonder what kind of lap top your powering. I'm looking at my old compaq laptop cord and it's 65 watts. Newer ones are usually way less than that. You can always forget the inverter and get a universal 12 volt adapter like this. http://www.amazon.com/gp/product/B008OPWDVM/ref=gno_cart_title_1 Linda S Quote Link to comment Share on other sites More sharing options...
stamar Posted November 2, 2012 Share Posted November 2, 2012 You need to connect directly to the battery. It won't work with the cigarette adapter. When I was using my 300 watt inverter I used the alligator clips and opened up the fuse door and clipped it directly to power there. my laptop uses less power than yours but it sucked the juice out of a group 27 deep cycle very fast. Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 2, 2012 Share Posted November 2, 2012 Think you reversed you numbers 120 watt @ 12 volts 10 amp. That must be a pretty big laptop that's about what my desktop draws. Most group 27's are 80 amp batteries so absolute best case 8 hours. With that kind of current draw you pretty well maxed out the cigarette lighter wiring they have pretty small wiring, clips or direct wired will be the only way. Quote Link to comment Share on other sites More sharing options...
waiter Posted November 2, 2012 Share Posted November 2, 2012 My cigarette plug used to be (the one on the Antenna amplifier) wired directly to the coach battery, thru a self resting Circuit Breaker. (I can't remember the size) It should support a small inverter Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 2, 2012 Share Posted November 2, 2012 My cigarette plug used to be (the one on the Antenna amplifier) wired directly to the coach battery, thru a self resting Circuit Breaker. (I can't remember the size) It should support a small inverter I don't know how much that ones good for either but the truck one's only wired with a #16 wire the coach one's more of an acc. plug so your right it probably has a higher current rating. Quote Link to comment Share on other sites More sharing options...
90toydolphin Posted November 2, 2012 Share Posted November 2, 2012 i use a 175 watt inverter plugged into the truck lighter and it runs our laptop fine. the laptop is about 3 years old, so not newer technology. maybe your lighter isn't supplying any power? bad fuse? Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 2, 2012 Share Posted November 2, 2012 I to have used 150 watt inverters for laptops I wonder if the OP's power supply's rating is what he assumed the laptop would draw? I hooked up a watt meter to one of my desk tops today here is what I got, box motherboard fans etc. 64 watts 17" monitor 26 watts so the whole works 90 watts. I plugged in my 15.3 " laptop max 45 watts while charging it's battery. So both are doable easily with a 150 watt inverter don't think I would like to run around with a desktop but the 150 would run it and even the truck lighter socket should run it. Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 2, 2012 Share Posted November 2, 2012 Just for kicks I just looked at the power supply for my brand new wiz bang all in one 23" do it all touch screen desk top computer, current draw max 2.4 amps @ 120 volts (288 watts) 7.2 amps @ 19 volts output. Quote Link to comment Share on other sites More sharing options...
stamar Posted November 3, 2012 Share Posted November 3, 2012 My laptop is an asus g72 from about two years ago about 150 watt power supply it will not work through a cigarette lights it needs a 300 Watt inverter connected directly to power. Quote Link to comment Share on other sites More sharing options...
Skydancer2992 Posted November 5, 2012 Share Posted November 5, 2012 My personal experience is that today's 12 volt accessory plug may short out the 90's vintage cigarette lighter socket, dependent on the orientation of the plug going into the outlet. I regularly run my laptop off my cigarette lighter via a 200 watt inverter but I keep spare fuses available. My longterm intention is to wire directly to the battery via an appropriate fuse. A 210 watt laptop at 120 volt will draw less than 2 amps (current = power divided by voltage) or (210 watts/ 120 volts). Most Toyota auto accessory circuits are rated at 15 amps max. Plenty amperage to spare while listening to the radio and cruising the internet in the McDonalds parking lot. Quote Link to comment Share on other sites More sharing options...
stamar Posted November 6, 2012 Share Posted November 6, 2012 In general you need twice the watts in an inverter than the laptops power supply. In general 200 watts and above need a direct connection. My inverter by go power has connections for both. It works connected directly and chirps in and out through the 12 volt receptacle in back My dolphin has a panel of glass fuses I put the alligator clips on the fuse for power in Quote Link to comment Share on other sites More sharing options...
zero Posted November 19, 2012 Share Posted November 19, 2012 . Are 12volt cigarette port connections not powerful enough to run this ? what is the most cost effective route to power my laptop ? thanks!! so glad these forums exist! Cigarette lighter type power outlets in automotive use are usually limited to 20 amps at 12-14 volts. An inverter can make a max output of around 200 watts when plugged into such an outlet. The normal wattage demand for a laptop power-supply is 65 watts. Your inverter should power your laptop just fine when plugged into that power-port unless that inverter makes such a poor modified wave - your lap-top power--supply is not compatible. Cheap inverters do NOT make the same type of AC power you get in your house. They make a stepped modified-wave with low voltage peaks and dips that do not work great with everything -especially some small AC to DC converters. Quote Link to comment Share on other sites More sharing options...
zero Posted November 19, 2012 Share Posted November 19, 2012 A 210 watt laptop at 120 volt will draw less than 2 amps (current = power divided by voltage) or (210 watts/ 120 volts). If a laptop was actually rated at 210 watts - it would draw around 20 amps at 12 volts when run through a small inverter. 20 amps is the "industry standard" limit on my 12 volt power outlets in cars and trucks. Quote Link to comment Share on other sites More sharing options...
zero Posted November 19, 2012 Share Posted November 19, 2012 In general you need twice the watts in an inverter than the laptops power supply. Not "generally" true. A typical mod-wave inverter runs at 85-90% efficiency. A lap top has a steady draw unlike a device with an electric motor that can surge on start-up. A lap-top rated at 65 watts usually draws 65 watts max. A device with a motor rated 65 watts may need 200 or 300 watts at first start-up. So, a lap-top with a 65 watt rating hooked to an 85% efficient inverter needs an extra 15% in wattage. That comes to a 75 watt total demand. A typical automotive power-port or cigarette lighter is usually rated at 200 watts. There are other factors though. With cheap inverters the quality of the AC "fake" sine wave is sometimes a big issue with certain devices including . . . AC to DC converters or battery chargers, GFIC outlets, and smoke/CO alarms. Since there is NO good way to know the quality of the AC power a cheap inverter makes by reading the published specs - finding out what works is often "trail and error." Note also that most of the much more expensive "True Sine Wave" inverters also do not make true sine waves. They do work better with many problem appliances - but will also work worse on a few then with a cheap mod-wave. This is why a consumer-level 2000 watt mod-wave inverter costs $120, and a consumer level "True/Pure Sine Wave" inverter costs $450, and 2000 watt inverter certified to make a true 60 cycle sine wave can cost $4000. Quote Link to comment Share on other sites More sharing options...
stamar Posted November 19, 2012 Share Posted November 19, 2012 nope a 200 watt inverter will not run a 150 watt laptop brick. but a 300 watt one will. personal testing for modified sine wave inverters obviously. a 200 watt one will chirp in and out off and on. in general for running a laptop you will need an inverter twice as big as the power brick, or more. and if you have apx 100 watt power brick or more, you will have to connect the inverter directly to a battery. several sources confirm this. dont bother trying to run a 65 watt laptop with a 100 watt inverter. Quote Link to comment Share on other sites More sharing options...
zero Posted November 20, 2012 Share Posted November 20, 2012 nope a 200 watt inverter will not run a 150 watt laptop brick. Some 200 watt units certainly will run a laptop from a power port and some will not. Not all inverters sold as "200 watt" are the same. That goes for inverters at any claimed wattage. Also - since most newer inverters have "unified trip breakers" they can turn off, and/or chirp and may not indicate to the user WHY it's happening. It can be an AC overload but can also be a DC input low-voltage problem, a heat problem, a incompatibility problem, etc. I've got a 150 watt inverter that can run my laptop just fine. Maybe what is needed is a thread that actually discusses specific makes and model numbers on inverters and what they can, or cannot do. I've got over 30 inverters and could add a good bit of test and use data. AIMs, Trace/Xantrex, Vector, Cobra, Black & Decker, Ramsond, Outback, Chicago Electric, Duracell, and more. I have them from 150 watts up to 10,000 watts in modified wave, so-called "true sinewave" and grid-power certfied 60 cycle sine-wave. Worst I ever had was a 4000 watt Vector/Black&Decke. It could not even run a small AC refridgeratror I have that only draws 6 amps max AC. I replaced the 4000 watt inverter with a 1000 watt AIMs and it works flawlessly on the same fridge. Note that after the bad experience with the 4000 watt unit I did NOT claim that no 4000 watt inverter can run a small fridge. Just that particular one. Quote Link to comment Share on other sites More sharing options...
stamar Posted November 20, 2012 Share Posted November 20, 2012 Your 150 watt inverter would not run my laptop that's some weird logic. Mine is a 150 watt brick. A 300 watt inverter will not run it through a cigarette lighter so really no inverter will regardless of what it is called as its beyond the maximum. If you were to type into google what size inverter should I buy what will come up is one that's twice the size of the power brick. And from there you're gold because if its 300 or over it will also include dirct connection clips or just noting. That's just a consumer grade inverter and they are going to be similar. Some are sold with their maximum number not their running number. But that's easy to figure out Mine is gopower but a cobra vector etc all roughlyy the same I have run the same laptop on 200 watt vector inverter and it did the same thing in fact any would because that's the maximum amount of juice the cigarette lighter let's out. Same inverter works directly connected and turns off and on in the cigarette lighter. Works bbetter with the laptop battery removed Quote Link to comment Share on other sites More sharing options...
zero Posted November 20, 2012 Share Posted November 20, 2012 Your 150 watt inverter would not run my laptop that's some weird logic. Mine is a 150 watt brick. A 300 watt inverter will not run it through a cigarette lighter so really no inverter will regardless of what it is called as its beyond the maximum. If you were to type into google what size inverter should I buy what will come up is one that's twice the size of the power brick. And from there you're gold because if its 300 or over it will also include direct connection clips or just noting. That's just a consumer grade inverter and they are going to be similar. Some are sold with their maximum number not their running number. But that's easy to figure out Mine is gopower but a cobra vector etc all roughly the same I have run the same laptop on 200 watt vector inverter and it did the same thing in fact any would because that's the maximum amount of juice the cigarette lighter let's out. Same inverter works directly connected and turns off and on in the cigarette lighter. Works better with the laptop battery removed We've got five laptops in my household. Three use a 65 watt power supply. My wife's Toshiba that has a 220 watt power supply. My Compaq has a 200 watt power supply. All our laptops are the same size. Some have AMD processors and some Intel. I suspect the power supply for the Toshiba is oversized and wastes a lot of power just making heat. Ironically my wife's computer is the slowest of the bunch. I'll also note that all our computers are not run on the fullest power setting. Most laptops are not unless you purposely set them that way. My Compaq with the 200 watt power supply usually draws 96 watts. In regard to power outlets in cars or trucks . . . 20 amps is the industry standard. Since a power plug makes its connection by friction, 20 amps seems to be the normal limit. 20 amps at 12-14 volts is 240 watts to 280 watts. That's the reason why the highest rated inverters for power-port use are usually maxed at 200 watts. Inverters typically are 90-95% efficient. So, if the inverter selling is telling the truth about it's max wattage - the math is fairly easy to do and an inverter does not need to be twice the rating of the laptop. That being said, MANY inverters are not capable of making near the wattage they claim. Same goes for many portable gas-powered generators. I have on occasion used my Compaq laptop hooked to a 150 watt inverter plugged in the cigarette lighter and it worked fine. I don't do it often since my RV already has three hard-wired inverters. A 1500 watt unit and two 2000 watt units. I not only camp with it. I also use it for mobile AC power and run power tools from it. There are many variables. One is the quality of the power port itself. Another is the inverter and IF it can really do as advertised. I have found MANY that cannot come close to their ratings. Vector/Black& Decker is one and there was another that was being sold in the Homeland catalogs I keep getting in the mail. I think the brand name was "Steel City" or something like that. I got a 1000 watt inverter from them that could not even supply 400 watts without tripping its breaker. Sometimes you cannot even rely on past experience with a particular model. I have a 2000 watt Chicago Electric inverter I bought 5 years ago for $89 (Harbor Freight). It has been rock-solid and a workhorse. I was so impressed with it's quality I bought another this spring for $129 on-sale from Harbor Freight. The new one looks the same but it's a piece of junk. Quote Link to comment Share on other sites More sharing options...
83 SunRader Posted December 28, 2012 Share Posted December 28, 2012 You need to connect directly to the battery. It won't work with the cigarette adapter. When I was using my 300 watt inverter I used the alligator clips and opened up the fuse door and clipped it directly to power there. my laptop uses less power than yours but it sucked the juice out of a group 27 deep cycle very fast. I'm also using a 500w inverter to run/charge my laptop. I can only charge the battery via the cigarette lighter, but to actually use and charge the laptop I have to be connected directly to the battery. Quote Link to comment Share on other sites More sharing options...
stamar Posted December 28, 2012 Share Posted December 28, 2012 ya through the cigaretter lighter mine can start strong but eventually will fade in and out to battery power. It can work if the battery is already charged or removed. It can definitely just charge the battery. Quote Link to comment Share on other sites More sharing options...
zero Posted December 28, 2012 Share Posted December 28, 2012 I'm also using a 500w inverter to run/charge my laptop. I can only charge the battery via the cigarette lighter, but to actually use and charge the laptop I have to be connected directly to the battery. The cigarette lighter itself is good for 200 watts. Are you saying your laptop uses more then 200 watts? Quote Link to comment Share on other sites More sharing options...
83 SunRader Posted December 29, 2012 Share Posted December 29, 2012 The cigarette lighter itself is good for 200 watts. Are you saying your laptop uses more then 200 watts? LOL - I actually have no idea how many watts my laptop uses (the label says 19.5 volts). I'm just saying that with the inverter that I purchased I can only charge the battery via the cigarette lighter, if I want to use the laptop I have to be connected directly to the battery. The inverter cost $50 perhaps it falls under what you had written in a previous post. "Cheap inverters do NOT make the same type of AC power you get in your house. They make a stepped modified-wave with low voltage peaks and dips that do not work great with everything -especially some small AC to DC converters". Quote Link to comment Share on other sites More sharing options...
zero Posted December 29, 2012 Share Posted December 29, 2012 LOL - I actually have no idea how many watts my laptop uses (the label says 19.5 volts). I'm just saying that with the inverter that I purchased I can only charge the battery via the cigarette lighter, if I want to use the laptop I have to be connected directly to the battery. The inverter cost $50 perhaps it falls under what you had written in a previous post. "Cheap inverters do NOT make the same type of AC power you get in your house. They make a stepped modified-wave with low voltage peaks and dips that do not work great with everything -especially some small AC to DC converters". The wattage will be on your AC power supply (that can waste a lot of power before it gets to your computer). A standard power port or cigarette lighter is rated at 240 watts. Most computers even with the AC power supply run on less then that. What inverter do you have? I've never heard of anyone offering a cigarette-lighter plug powered inverter rated over 200 watts. 500 watts makes no sense since that's twice what any port can supply.. Quote Link to comment Share on other sites More sharing options...
83 SunRader Posted December 30, 2012 Share Posted December 30, 2012 What inverter do you have? I've never heard of anyone offering a cigarette-lighter plug powered inverter rated over 200 watts. 500 watts makes no sense since that's twice what any port can supply. The inverter is a Schumacher PID-500-usb. It offers a cigarette input and 2 alligator clips to connect directly to the battery. Schumacher's 500 Watt Power Inverter features a 1000 Watt peak and 500 continuous Watt, with two 120 Volt, 3 prong, AC household outlets and a USB Port. Also features a convenient and easy-to-read digital display, two LED indicators, an on/off switch, and a built-in high speed cooling fan. Includes thermal and surge protection, with a low battery alarm and cut-off, and a high battery voltage shutdown for safe and easy use. Quote Link to comment Share on other sites More sharing options...
Maineah Posted December 31, 2012 Share Posted December 31, 2012 You should have no problem running your laptop with a 100 watt inverter so say 150 for a little hard room the worst power draw I have seen directly from the ac mains through a watt meter was 58 watts charging a dead battery during boot up with 3 different computers the power draw was in the 20-30 watts range with a charged battery. Using a 500 watt inverter to power up less than 100 watts is not the most efficient the closer to rated power the more efficient they become. Most of the inverters sold just for laptops are in the 100 to 200 watt range mostly around 150 watts. If yours won't work from the lighter socket the problem is the socket and or wiring. Was the previous owner a smoker? If they were the socket maybe nasty. A 500 watt unit isn't going to make 500 watts with a lighter socket. One of the tests I did the idling current with a 350 watt inverter was 8 watts at 12 volts that's a fair amount of current for doing nothing and it does carry over to the operating current. The best way to simply power your laptop is a DC to DC converter I have found that laptops will work directly powered with 12 volts but the way the internal computer power supply is designed 12 volts is not enough to properly charge the battery. The difference is actually slight between 12 volts direct and a DC to DC converter (around a 1/2 a watt) so the DC to DC converter wins by convenience and the ability to charge the battery. Quote Link to comment Share on other sites More sharing options...
zero Posted December 31, 2012 Share Posted December 31, 2012 The inverter is a Schumacher PID-500-usb. It offers a cigarette input and 2 alligator clips to connect directly to the battery. The Schmacher manual for the PID-500-USB says it has a max of 120 watts if used with their cigarette lighter cord/plug. That's a pretty poor rating its only half the power available from a standard power outlet or cigarette lighter. Schumacher also shows an unusually low efficiency of less then 80%. I've never seen any other inverter rated that low. Usually the cheaper modified-wave inverers are 85-92% efficient. Going by Schumacher's own ratings of your inverter - once the large loss is factored in - it is only rated for 100 watts when used in a power port. That might be your problem. Many laptop AC to DC power supplies run at 120 watts. I suspect if you bought a different make and smaller inverter more sized for the laptop it would work much better. Something like a 200 watt. Of course, better yet is to just use a DC to DC boost converter like you posted links to Quote Link to comment Share on other sites More sharing options...
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