Inverter or DC-to-DC for laptop, etc.? - SailNet Community
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post #1 of 27 Old 10-27-2009 Thread Starter
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Inverter or DC-to-DC for laptop, etc.?

Hello,

I'm in the process of figuring out what minimal addition to make to the electrical system of boat to support my mobile office . Essentially, I only need to run my laptop and a few other lower power devices, most of which can be charged via USB or 12V adapter. I'm trying to decide whether to get a simple pure sine wave inverter, or just a DC-to-DC converter (the laptop runs at 15V). Any thoughts out there? I'd like to be an energy miser. Which option would be more efficient? I was looking at a Sinergex PureSine II 200W inverter. Anyone have any opinion on these or Sinergex?

Thanks, Colin
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post #2 of 27 Old 10-27-2009 Thread Starter
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Actually, it looks like the iGo everywhereMAX might work very well for my needs (minus not resisting the marine environment especially well, I assume). Anyone using these? Any opinions?

-Colin
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post #3 of 27 Old 10-27-2009
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Colin,

I think a lot of us would like to be using some sort of dc to dc power option. Nearly all the devices I use on my boat actually run on dc power (laptop, cellphone, camera, vhf), but have ac adapters to charge.

I don't have any experience with the products you are mentioning, and probably others don't either. That's why you aren't getting much response. If you use the iGo, I would love to hear about your experience. I think I have seen the adapters in radio shack. Personally, I use a cheapy 300 watt inverter from radio shack. It gets the job done, even if a little inefficiently.

Scott
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post #4 of 27 Old 10-27-2009
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I just use a cheap inverter that plugs into the lighter plug and I plug the laptop into that. It charges the lap top batteries and the lap top runs off that. I know its not a pure sine wave but I have not noticed any problems.

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post #5 of 27 Old 10-27-2009
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I would go with a dc-dc converter. There is a lot less 'loss' in the conversion. With an inverter, you step it up to 120v ac, then back down to 15vdc, experiencing losses with each conversion, going DC-DC you still experience loss, but only once.

Also, many laptops actually run internally on 12v, the charger/power supply is often larger for various reasons.
Should be able to determine the actual internal power requirements off the makers web page.

Ken.
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post #6 of 27 Old 10-27-2009
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I was able to find a DC to DC charger for my Compaq laptop, work fine with a lot less draw.

Have an inverter but rarely use it except to grind coffee

Cheers,
Shawn

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post #7 of 27 Old 10-27-2009 Thread Starter
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Great! Sounds like DC-to-DC is the best bet for my needs. I won't be getting my boat (assuming the purchase goes through) into the water until spring, but if I get an iGo, I'll report back on it.

-Colin
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post #8 of 27 Old 10-27-2009
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As stated above, avoiding energy conversions is a lot more efficient. Many laptops have an optional 12V power source that you can purchase.

The major advantage of an inverter is that sooner or later, you will have something that you want to charge/run which you do not have a dc plug for.
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post #9 of 27 Old 10-27-2009 Thread Starter
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klem,

My concern with 12V laptop power supplies is that they are made for cars usually and that boats tend to have wider voltage ranges. In any case, my laptop runs on 5A@15VDC. Not sure how lower voltages would effect it. The iGo apparently comes with $100,000 laptop replacement insurance (I'm betting they'll have a marine exclusion though )

The car supply for my laptop sold by Toshiba is simply the Targus Universal 90W AC/DC Power Adapter. Both this and the iGo have the ability to charge multiple devices which is key. I'd love to know which is more rugged/efficient/voltage flexible. The good thing is that with either one I might be able to leave a bunch of my factory original chargers at home and spare them the marine environment.

From a iGo review comment here by Reinhard:

iGo 130w Everywhere with magsafe

it would seem that the iGo is much more efficient than an inverter (lost electrical efficiency is usually obvious as heat.) No surprise there, I guess.

As far as running other stuff goes, I'm planning to keep my electrical needs minimal and will really only have laptop and fridge as major draws. Hopefully any weird AC equipment I have can be reserved for the rare shore power hookup.

Cheers, Colin
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post #10 of 27 Old 10-27-2009
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I used both methods. I've never measured consumption one way or another, so my observations are strictly just observations

DC-AC-DC inverter burns a lot of energy. I have 600 wt inverter and powerful laptop and it can drain house battery very fast.

It seems like DC-to-DC converters are more gentle on power consumption. However they fail in marine environment. I had ran through 4 converters in about a year, two of them were brand names designed for my laptop, and two were cheap no-name. Actually one cheap one last longest time, about 3 months.

Now I charge my computer with DC-AC inverter, I have it for 4 years, it was cheaper than DC-DC chargers and it works...
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