power inverters and laptops question
Submitted: Sunday, Apr 06, 2008 at 12:56
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Member - Dirk B (VIC)
G'day all. I'm planning to run Oziexplorer on my laptop with a GPS mouse for my next trip. But I've struck trouble with the power inverter and the laptop. Would appreciate some advice from anyone with experience of the following:
I've purchased an IFONX 150 watt inverter. The back of the package, and everything I've read elsewhere, suggests that a laptop draws about 80 watts. So that should be plenty of room. So long as the laptop is not turned on, I have a green light on the inverter that says 'everything's cool'. However, if I turn on the laptop, then I get the red overload switch. This seems odd, since the DC output from the inverter on the laptop is 16V x 3.75 amps. So given Ohm's law, should draw 60 watts.
The other thing that crossed my mind is that the laptop may want a pure sine wave, but the output of the inverter is a modified one. But this contradicts the advice I was given by the bloke at TJM. Since the power supply charges the laptop's battery and the battery supplies power to the laptop when it is running, this shouldn't matter. It would matter if you were running a desktop PC in your truck, but not a laptop.
Or is it possible that different laptops do it differently? For the record, the laptop is an old Fujitsu Lifebook S6120. Not particularly flash, but compact, rugged and lightweight.
Would love to hear from anyone who's got any insight into this problem.
Reply By: Member - joc45 (WA) - Sunday, Apr 06, 2008 at 15:12
Sunday, Apr 06, 2008 at 15:12
Hi Dirk,
Some laptop power supplies require quite high transient input current pulses. Some smaller
inverters cannot deliver these high current pulses, and a higher wattage inverter is required. This does not mean that the laptop will consume more than the 60 watts specified.
But really, I suggest you look at a DC-DC converter.
Places like Dick Smiths and Jaycar flog a range of them, especially made for laptops, with selectable output voltages and a range of dc adaptor plugs for the laptop. eg, Jaycar CAT. NO. MP3463 for about $35.
Gerry
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Reply By: Member - Jim S (NSW) - Sunday, Apr 06, 2008 at 19:01
Sunday, Apr 06, 2008 at 19:01
I have no trouble running my laptop from a 150W modified sine wave inverter .... (It's a Toshiba 100 with 14" screen purposely bought for low power consumption) A friend had heaps of trouble (tripping out) but it turned out to be the aux battery was buggered and voltage was low ... Installed new aux battery .... BINGO works fine..... (he had a 17" screen Toshiba, too big for the bush)
If you measure the current on the DC side of the inverter for your laptop it's would be about 6 amps (may be higher) allowing for the efficiency of the inverter,etc .... You could try connecting your inverter directly to the battery and run a 240V lead to the PC, can help sometimes as voltage drop on the 12V side can have quite a large effect on the inverter ... Plugging
inverters into cigarette lighter sockets can cause problems with voltage drop also ....
The best solution is to get a 12V power supply to suit your laptop but ensure that it has enough power to run the laptop as they are not always available or able to run large laptops ....
NOTE: Some large Laptops, eg. those with 17" screens, powerful processors and DVD players need a 300w inverter .... (If the battery is low, the inverter will trip out when the laptop is connected) Also note that running a DVD movie uses quite a bit of power and the laptop needs to be connected to the inverter while running the movie .... The internal battery will only last about 15 minutes .....
With regard to getting an electric shock from a 240V inverter .. You would need to be connected between the active and neutral as
inverters are usually isolated from earth so VERY unlikely ...
AnswerID:
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Follow Up By: Member - Graham H (QLD) - Sunday, Apr 06, 2008 at 20:27
Sunday, Apr 06, 2008 at 20:27
Projecta make several models of laptop 12volt converters.
I see they are up over 90 watts now so you should be able to get one to suit. If you are worried about the battery take it out.
Most will run on exterior power Ok.
I also have a WAECO 100watt can type inverter which runs my 14 in Compaq ok but prefer the low voltage way.
The 65 watt Projecta runs it fine with all the bells and whistles like Bluetooth, 4 way USB hub, cordless mouse USB wireless internet etc
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