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Old 30-12-2011, 15:42   #1
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Hummm ? Using an Inverter to charge a laptop ...

Hi all ..
I have a new HF Freedom 1000w charger/inverter installed on my sailboat. I believe it puts out a modified sine wave. When I plugged in my Dell laptop to charge it, the adapter began to hum. ... The Link battery monitor showed that there was a 2.5 amp load on system (which is what the adapter says it draws), but the humming concerned me (as well as my brother's opinion that he thought he smelled something overheating -- not sure about that though).
I tried to look at Dell's website and other posts, but the opinions were all over the map whether there is an issue doing that .... I don't "mind" frying the adapter, but I don't want to risk doing anything to the interter or the computer (as they are both big bucks!)....
Thanks.
SG
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Old 30-12-2011, 15:49   #2
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Re: Hummm ? Using an Inverter to charge a laptop ...

see previous posts on pure sine wave inverters,mod sine waves dont allways work with some types of voltage regulators or electronics with switching circuits in them

think the thread was "dremel drill doesnt work on inverter"
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Old 30-12-2011, 16:16   #3
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Re: Hummm ? Using an Inverter to charge a laptop ...

I have a 600w inverter and found that charging a laptop on it was highly inefficient. Bought a DC power adapter cable and that seems to work much better for my laptop.
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Old 30-12-2011, 16:25   #4
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Re: Hummm ? Using an Inverter to charge a laptop ...

Have a look at sine wave and modified sine wave converters on Google,
They have a lot of info on there about the inverters,

Mine was a pure sine wave inverter so I didnt have any problems with my computer plugged in,or charging it,

The modified inverter does have some kind of Flow thingy problem with it,

I was looking for a new bigger inverter to replace mine after it sank, So I got a lot of good info on it,

Pure sine wave inverter against modified pure sine wave converter,

Whats the difference between Pure sine wave and Modified sine wave inverters,

I am Mechanical, not Electrical,

I was looking at a 10,000 watt, Pure Sine Inverter, 12 volt DC, 240 AC 50 Hrtz, 100 % duty cycle $500-00 AUD delivered from China. The charger was $150-00 AUD and the meter was $50-00 AUD

Hope this helps,
Brian,
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Old 30-12-2011, 17:21   #5
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Any time you hear these 100-120 Hz hums you can be sure it is a problem with the AC service. These days I see no reason to install anything other than true sine inverters, which will eliminate all these problems around modified sine wave. Some people however prefer those and select everything they buy on being able to use modified sine

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Old 30-12-2011, 17:29   #6
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Re: Hummm ? Using an Inverter to charge a laptop ...

We have been using modified square wave (cheapo) inverters to run our (then) Dell and Acer, (now) an Asus. No issues.

The only piece of equipment we did run into issues was our AA (NiMH) battery charger - and yet it worked too (even though I expect the batteries got less than optimally charged).

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Old 30-12-2011, 17:41   #7
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Re: Hummm ? Using an Inverter to charge a laptop ...

Like barnakiel, we have been charging our laptops for years with modified sine wave inverters, including this one right now. BUT, if you are having a problem and don't want to replace the entire system just to charge your laptop, then get a DC to DC converter and run the laptop off your 12 volt system and charge it at the same time. Problem solved with very little expense. Chuck
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Old 02-01-2012, 11:25   #8
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Re: Hummm ? Using an Inverter to charge a laptop ...

Thanks for the all the help. The computer is a newer Dell ... It seems to be hit or miss because the powerpack did start to hum for me ... I think that I'll look into a DC to DC ... and/or Dell sells a 12V for my computer so maybe I'll get that and plug it into the 12V slot instead of inverter.
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Old 02-01-2012, 11:30   #9
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Re: Hummm ? Using an Inverter to charge a laptop ...

Quote:
I think that I'll look into a DC to DC
Much more efficient that way
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Old 02-01-2012, 11:43   #10
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Re: Hummm ? Using an Inverter to charge a laptop ...

Quote:
Originally Posted by sailgreen View Post
Hi all ..
I have a new HF Freedom 1000w charger/inverter installed on my sailboat. I believe it puts out a modified sine wave. When I plugged in my Dell laptop to charge it, the adapter began to hum. ... The Link battery monitor showed that there was a 2.5 amp load on system (which is what the adapter says it draws), but the humming concerned me (as well as my brother's opinion that he thought he smelled something overheating -- not sure about that though).
I tried to look at Dell's website and other posts, but the opinions were all over the map whether there is an issue doing that .... I don't "mind" frying the adapter, but I don't want to risk doing anything to the interter or the computer (as they are both big bucks!)....
Thanks.
SG
Dell makes a nice travel power supply for their notebooks. Can use AC or 12 vdc.
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Old 02-01-2012, 12:20   #11
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Re: Hummm ? Using an Inverter to charge a laptop ...

You may be surprised as to how inefficient DC to DC power converters can be. I bought a cheap Chinese unit (and maybe that is the problem) to power my netbook. It drew about 4 amps at 12V DC to produce about 2+ amps at 19 V DC to power the netbook.

A West Marine cigarette lighter plug in inverter uses 3-3.5 amps DC to power the inverter while it feeds the netbook's power brick.

So the inverter/brick power source uses less amperage than the DC converter.

David
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Old 02-01-2012, 13:06   #12
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Re: Hummm ? Using an Inverter to charge a laptop ...

Quote:
Originally Posted by Waterwayguy View Post
Like barnakiel, we have been charging our laptops for years with modified sine wave inverters, including this one right now. BUT, if you are having a problem and don't want to replace the entire system just to charge your laptop, then get a DC to DC converter and run the laptop off your 12 volt system and charge it at the same time. Problem solved with very little expense. Chuck
That little one looks nice with the included plugs.

Anyone seen one with a USB plug?

Seems lots are arriving at that system now to charge "things".
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Old 02-01-2012, 13:11   #13
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Re: Hummm ? Using an Inverter to charge a laptop ...

I had an old Fredom 1000 that charged the laptop fine. One toshiba laptop I had was 12volt, i considered going 12v direct but never got around to doing it...
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Old 02-01-2012, 13:59   #14
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Re: Hummm ? Using an Inverter to charge a laptop ...

Quote:
Originally Posted by djmarchand View Post
You may be surprised as to how inefficient DC to DC power converters can be. I bought a cheap Chinese unit (and maybe that is the problem) to power my netbook. It drew about 4 amps at 12V DC to produce about 2+ amps at 19 V DC to power the netbook.

A West Marine cigarette lighter plug in inverter uses 3-3.5 amps DC to power the inverter while it feeds the netbook's power brick.

So the inverter/brick power source uses less amperage than the DC converter.

David
It is unusual for a DC to DC converter to use more power than an inverter and AC to DC converter. Generally they use about 30% less, but the electronics can be done several ways so its not impossible to design a very inefficient DC to DC converter, but it is unusual. I never seen one that was worse than the inverter alternative .Are you sure the battery was not charging when you took the readings?
The consumption of my netbook on a DC to Dc converter is about 1.2A @ 12.5v which is much lower than you are getting .
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Old 02-01-2012, 18:03   #15
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Re: Hummm ? Using an Inverter to charge a laptop ...

Nolex:

The numbers I quoted are from memory, but the relative difference is accurate. They were measured with a clamp on DC ammeter on the actual circuit feeding the inverter or converter.

I agree, DC converters should be more efficient, but this Chinese POS certainly wasn't. But it was really cheap, about $15 from Hong Kong!!!

David
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