Meltdown07 Posted December 21, 2007 Share Posted December 21, 2007 Hey guys, I have a stupid question here for you. (or rather what I think is probably a stupid question). Do Power Inverters suck enough juice off the battery where you have to worry about the car losing power on a long trip? Case-in-point, I am driving up to IL starting tonight (14 hour drive), my girlfriend is bringing her laptop in the Legacy to watch movies on the drive. The inverter is a 100W inverter. If the laptop is plugged into it constantly for the drive do I need to worry about the battery dying or anything? I will be using the stereo/HVAC while she watches movies with her headphones on. Thanks guys! Go Cardinals! Link to comment Share on other sites More sharing options...
gary_gnu Posted December 22, 2007 Share Posted December 22, 2007 No, there's no problem with running a 100w inverter in your car while the engine is running. You'll be fine. Link to comment Share on other sites More sharing options...
TSiWRX Posted December 22, 2007 Share Posted December 22, 2007 The wifey's been using "our" laptop a lot lately, so I've taken to using one of my old laptops for datalogging - unfortunately, my old laptops are all 3+ years old, and their NiCd packs have expired...as a result, I usually run the laptops off an inverter. I usually do 20 to 30 minute stretches, probably as long as one or even one-and-a-half hours, but I haven't noticed anything strange from my voltmeter readings. Unfortunately, my electrical knowledge is rather short, and covers only the very basics. Aside from reporting this observation, I can't help you much at all. However, I am interested in this information, myself. <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
CzarDestructo Posted December 23, 2007 Share Posted December 23, 2007 I believe all the Legacys use a 1100watt alternator so the 110-130 watt load from that inverter (they're not 100% efficient) is meager compared to what it actually can handle. Also, just because an inverter can handle 100watts doesn't mean your laptop will actually tax it to full load. The laptop may only need 50 or so watts, for example. To figure out the wattage of the laptop flip over the power brick and read the info on the back. Wattage equals Amperage x Voltage. So if the laptop uses 24V DC and the brick puts out a max of 3.5 amps, thats 84 watts absolute worst case scenario. And even still, the laptop will almost NEVER use the full capacity of the power brick. Probably half of that. If you had a crazy sound system as well as this inverter and some other toys, then you might have to worry! Link to comment Share on other sites More sharing options...
SpecBee Posted December 24, 2007 Share Posted December 24, 2007 I've used a 300 watt inverter for 12 hour road trips without a problem. Your Alternator should be able to put out enough power for all of your loads including the cig lighter or both lighter sockets for say 80% of the amperage rating for the fuse. Link to comment Share on other sites More sharing options...
AKLGT Posted December 24, 2007 Share Posted December 24, 2007 i have run anything from a craptacular Car PC, laptop, 7" LCD monitor, inverter and 6 12V on a 3000 mile road trip. no issues. of course, you'll want to make sure everything is off when the car isn't running or you will have issues. Wiggle wiggle wiggle wiggle wiggle yeah!!! Link to comment Share on other sites More sharing options...
mwiener2 Posted December 24, 2007 Share Posted December 24, 2007 Wow you guys all missed a really simple answer. As long as the car is running, you can't pull enough juice out of the cig lighter port to hurt anything. The fuse will blow long before you get to that point. With the car off, worst case you drain the battery. And the fuse will still blow if you try and suck too much. Stock GT alternator is 110amps. I think the cig lighter is 15 or 20amp fuse. That's 180-240 watts with the engine off and 216-288 watts with the engine on My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
AKLGT Posted December 24, 2007 Share Posted December 24, 2007 Wow you guys all missed a really simple answer. As long as the car is running, you can't pull enough juice out of the cig lighter port to hurt anything. The fuse will blow long before you get to that point. With the car off, worst case you drain the battery. And the fuse will still blow if you try and suck too much. Stock GT alternator is 110amps. I think the cig lighter is 15 or 20amp fuse. That's 180-240 watts with the engine off and 216-288 watts with the engine on right. that's why i said, as long as it's RUNNING. otherwise, you will drain your battery if you forget to turn things off. Wiggle wiggle wiggle wiggle wiggle yeah!!! Link to comment Share on other sites More sharing options...
Meltdown07 Posted December 25, 2007 Author Share Posted December 25, 2007 lol. Thanks guys. Made it up to St. Louis from Austin no problem. The girl slept most of the drive. We left at 7:30PM and arrived in STL at 9AM. Yikes. It was awful. Go Cardinals! Link to comment Share on other sites More sharing options...
apexi Posted December 19, 2010 Share Posted December 19, 2010 I'm new to power inverters and I'm hoping someone can help me. I'm thinking about getting a power inverter that supplies a continuous 200w and 400w peak. I'm worried about this because the lid on my cigarette lighter says 12v 120w, so would this be dangerous to do on the stock cigarette lighter wiring? Do I need to find an inverter that is less than 120w? Link to comment Share on other sites More sharing options...
ssbtech Posted December 19, 2010 Share Posted December 19, 2010 It would be wise to use a smaller inverter. What are you powering from it? Link to comment Share on other sites More sharing options...
apexi Posted December 19, 2010 Share Posted December 19, 2010 Probably just a laptop with a 90w charger, cell phones, etc. Laptop would probably be the biggest item. So it seems like a 100w inverter should work, but im not sure if I should try to find something a little bigger than 100w so theres more than a 10w buffer Link to comment Share on other sites More sharing options...
ssbtech Posted December 19, 2010 Share Posted December 19, 2010 If the laptop's charger is rated at 90 watts then the laptop is most likely pulling less than 90 watts. That will be the maximum current it draws - ie, playing a game while burning a CD with all the USB ports loaded to maximum capacity. Even then it's doubtful it will suck all 90 watts. Your 200w inverter will be fine plugged into your cig lighter, just don't plug anything into it that draws more than 100-110 watts. Link to comment Share on other sites More sharing options...
apexi Posted December 19, 2010 Share Posted December 19, 2010 That's what I was thinking. My desktop computer has a 600w power supply, but accoring to my UPS the computer is only pulling around 140w from the UPS most of the time. So I wasn't sure if I'd be ok going with a higher power inverter, but keeping the power draw less than 120w. Just to be safe, I decided to go with a 100w inverter instead of the 200w one I was considering. Thanks for the help Link to comment Share on other sites More sharing options...
UnXpectedError Posted December 20, 2010 Share Posted December 20, 2010 I have a 1000Watt Inverter and it runs fine from the Cig Lighter provided i'm only using a laptop. If i'm running anything big (Like lights, Sound System etc while camping) I hard wire the inverter to the Battery Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.