Is a power inverter safe for laptops and iPods?
During an upcoming vacation in an RV, our family will want to charge their Apple laptops and iPods as usual, but of course there won't be any wall outlets like there are in a house. Instead, we have a little gadget called a power inverter from Radio Shack, made in Taiwan by Enercell, that can be plugged into an electrical outlet connected to the car's battery. Here's a picture of the thing: http://tinyurl.com/ 23fequ8. I wonder if it's safe to the electronics to use this inverter? It says on the package: 150-watt power inverter. Equips your vehicle with a household electrical outlet and USB port! Power your home electronics from your car! Continuous AC power: 150W. Peak power: 300W for one cycle. Output voltage 115 VAC + - 10 VAC, 5 VDC + - 0.25 VDC. Output frequency 60Hz + - 3Hz. No-load current draw 0.4A. Caution: total combined power of devices plugged into this inverter should not exceed 150W. Anybody see a problem with plugging a Powerbook, a MacBook, or an iPod into this thing? (Not all at once, of course). Thanks much! Tom -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
Re: Is a power inverter safe for laptops and iPods?
At 10:51 AM -0700 7/14/2010, Tom wrote: During an upcoming vacation in an RV, our family will want to charge their Apple laptops and iPods as usual, [...] power inverter from Radio Shack [...] Anybody see a problem with plugging a Powerbook, a MacBook, or an iPod into this thing? (Not all at once, of course). My housemates travel all over the country in their RV. Everything works fine on their inverter. But they have had difficulties in the past with cheap inverters... Something about the a/c not being a smooth enough wave to make the wal-warts and rechargers happy. Best to try things in advance... - Dan. -- - Psychoceramic Emeritus; South Jersey, USA, Earth. -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
Re: Is a power inverter safe for laptops and iPods?
On Jul 14, 2010, at 11:08 AM, Dan wrote: At 10:51 AM -0700 7/14/2010, Tom wrote: During an upcoming vacation in an RV, our family will want to charge their Apple laptops and iPods as usual, [...] power inverter from Radio Shack [...] Anybody see a problem with plugging a Powerbook, a MacBook, or an iPod into this thing? (Not all at once, of course). My housemates travel all over the country in their RV. Everything works fine on their inverter. But they have had difficulties in the past with cheap inverters... Something about the a/c not being a smooth enough wave to make the wal-warts and rechargers happy. Best to try things in advance... Ooh, thanks for the advice! Our new car came with one built-in, and we were planning on using it on our vacation this year... -- Bruce Johnson University of Arizona College of Pharmacy Information Technology Group Institutions do not have opinions, merely customs -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
Re: Is a power inverter safe for laptops and iPods?
At 14:08 -0400 7/14/10, Dan wrote: Best to try things in advance... Yep. And it would be pretty hard to find a power converter that would damage any of today's computer power converters. If it doesn't work don't leave it hooked up too long and pay attention to hot spots that shouldn't be. Cheap converters for automotive cigarette lighters almost always convert to a square wave form of AC power. The voltage changes quickly from +115 volts to -115 volts about 60 times per second. That's quite different from utility power that changes as a smooth sine wave that averages out (in delivered power) to 115 volts. More expensive converters as found in mobile homes do a better job matching the voltage waveform. The internal power converters in computers these days make an effort to avoid drawing current that is not sinusoidal. It's called harmonic suppression and is required in many countries but not in the US of A. When the harmonic suppression circuitry encounters a square wave voltage, which has terrible harmonics to start with, it can get confused and not work properly because it tries to accept current only while the voltage is changing. For a square wave the voltage is only changing for very short periods of time. ftp://ftp.macnauchtan.com/Theory/Harmony_101.pdf Is a piece I wrote a long time ago about it. You'll need to know a little math and electricity but it's pretty short. -- -- Evolution made it possible for mankind to invent religion. -- -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
Re: Is a power inverter safe for laptops and iPods?
I have for several years used inverters, for the most part all is well, BUT here are some issues: The output of all under $500. inverters is a simple square wave -(1 step) not even a modified sine wave. Above this price range you may find a stepped sine wave output - the number of steps used to approximate the sine wave is a measure of quality -3 steps or 25 steps, but again is only a problem under specific circumstances. I have charged laptops, ran G4s and printers all with no problems, but some of the power supplies are designed as a switching basis to use less iron and so lower in weight but this causes the effect of the square wave to be more of a problem. It is especially important that you NOT use near the limit - a 50 watt should not be more than 80% loaded as the wave will fail and as you are connecting a transformer to what you want it to see is ac, but when the wave form fails, it is dc and no inductive reactance will cause it to have VERY HIGH CURRENTS burning out your supply. JML From: Dan dantear...@gmail.com Subject: Re: Is a power inverter safe for laptops and iPods? To: g3-5-list@googlegroups.com Date: Wednesday, July 14, 2010, 11:08 AM At 10:51 AM -0700 7/14/2010, Tom wrote: During an upcoming vacation in an RV, our family will want to charge their Apple laptops and iPods as usual, [...] power inverter from Radio Shack [...] Anybody see a problem with plugging a Powerbook, a MacBook, or an iPod into this thing? (Not all at once, of course). My housemates travel all over the country in their RV. Everything works fine on their inverter. But they have had difficulties in the past with cheap inverters... Something about the a/c not being a smooth enough wave to make the wal-warts and rechargers happy. -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
Re: Is a power inverter safe for laptops and iPods?
On 7/14/10 11:41 AM, Doug McNutt wrote: At 14:08 -0400 7/14/10, Dan wrote: Best to try things in advance... Yep. And it would be pretty hard to find a power converter that would damage any of today's computer power converters. If it doesn't work don't leave it hooked up too long and pay attention to hot spots that shouldn't be. Switching power supplies rarely have problems. Linear supplies (the denser wall warts) can have problems but are usually okay. Cheap converters for automotive cigarette lighters almost always convert to a square wave form of AC power. The voltage changes quickly from +115 volts to -115 volts about 60 times per second. That's quite different from utility power that changes as a smooth sine wave that averages out (in delivered power) to 115 volts. They actually switch from +160V (or so) to zero to -160 to zero and back to +160. It's what is called a modified sine wave (modified square wave would be more accurate). More expensive converters as found in mobile homes do a better job matching the voltage waveform. Even many of the high power inverters are modified sine wave. The internal power converters in computers these days make an effort to avoid drawing current that is not sinusoidal. It's called harmonic suppression and is required in many countries but not in the US of A. When the harmonic suppression circuitry encounters a square wave voltage, which has terrible harmonics to start with, it can get confused and not work properly because it tries to accept current only while the voltage is changing. For a square wave the voltage is only changing for very short periods of time. I haven't encountered any problems like that but I could see it happening. I have several battery packs that I charge from solar panels for field use. The loads are either 12V (LED lighting), off an inverter or car adapters for the laptops. I prefer using the car adapter instead of the inverter / AC power supply as it's more efficient. I don't worry about leaving them plugged in and running down the battery. The OP listed an inverter that draws .4 A with no load. While that's not a lot of power it can run down the battery if your not careful. The laptop, once it's fully charged draws much less power when using an auto adapter. Most digital equipment will work okay with an inverter output. TVs (older analog sets) and radios may have significant noise because of the inverter. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting I'm a designated driver on the Information Super Highway -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
