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Old 03-12-2009, 15:23   #31
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Unbusted: Save yourself the math and guesswork. Get thee to thy nearest Home Despot and buy a thing called the "Kill-a-watt". It's a meter that you plug into an outlet, then you plug your laptop into it and it records exactly what your Toughbook (or any other 110v 60Hz device) uses. The nicer ones will tell you what your monthly or annual consumption is, and even calculate your costs if you input a price per kWh.
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Old 03-12-2009, 16:58   #32
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I am a belt and braces person... I take paper charts and at least 2 GPS systems.
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Old 03-12-2009, 16:59   #33
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And I just installed Navionics Marine Maps on my Iphone
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Old 03-12-2009, 17:24   #34
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Boy, it is hard to run a simple boat!

But - - our problems pale into insignificance if you read another thread discussing whether a 3.5 kw generator will even START their systems!

Good advice here e.g. charging from 12v DC a measuring ampage. If these ideas don't resolve your question you can always consider lower power ways of getting a chartplotter. A net book could halve power use, my 5" Navman only uses 0.6A (?), I think the B&W versions use half that, and then there are small screen handhelds. Yep, some might cost more. Just expanding the choices offerred.

(I see Masquerade has just posted a similar 'less power' idea.)

My boat may have a similar setup to what you propose, and I would soon turn off anything that drained 2+ amps. Hell, I could run a small fridge off some of the ampage numbers being discussed!
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Old 03-12-2009, 22:32   #35
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How far do you plan to cruise? Why not paper charts. You may be making your needs more complex than they need to be. What happens when you run out of power at the same moment you need to navigate. You need paper as a back up any way.
BTW I see your on a new boat. What happened to Ruffian?
Well we were sailing in Ruffian and a fog bank rolled in and our battery bank was dead so we had no GPS and we ran aground...No I'm just kidding she's still in San Diego with her 400Ah bank and her 240 Watt solar array.

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My boat may have a similar setup to what you propose, and I would soon turn off anything that drained 2+ amps. Hell, I could run a small fridge off some of the ampage numbers being discussed!
What is your boat's set up? What do you use for navigation?
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Old 06-12-2009, 15:34   #36
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I run a single 130 Ah battery, and charge from 30 W in solar panels. My 15 hp Mariner is hand start; not fitted with 5A alternator (don't need it).

With this setup, I cruise for weeks at a time, but cannot run all day on tiller pilot. So this set up is mainly for hand-helmed coastal cruising. My navigation 'essentials' (other than lights) are paper charts, GPS handheld, a stack of rechargeable AA batteries, and a 12v charger.

With pilotage skills and preparation for new waters, I don't run plotters much. A few years ago I used paper charts (one is always in the cockpit) with waypoints marked and e-trex on my neck (batteries last ~10 hrs). Loaded charts or coastal outlines would make this even more useful.

I added a 5" colour chartplotter (~0.6A), which gets turned on going into tight corners, at night (confirm position / avoid disorientation), and in less familiar areas. You can use your portable on a 30W panel, just not all the time. And perhaps charge it direct from your 12v source.

Sounds like I am flaming, but VHFs & COLREGS lighting are my biggest must haves on the consumption side of my 12v power budget. And high output LEDs have really brought down the demands of all lighting.
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Old 31-12-2009, 15:10   #37
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Also, FWIW, the inverter loss can be quite significant. The "DC to DC" converters are also inverters.... the DC voltage multipliers rely on an oscillator to make the DC to AC, step it up, and then rectify it back to DC. They are more efficient then the alternative because they are purpose specific but there are still losses.
I just spoke with the people from Lind who make the Toughbook DC/DC power supply and the rep said that this was not true and that at no point do their power supplies invert to AC he quoted a %90 efficiency.

DC Power Adapters for Panasonic Computers first product in list
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Old 31-12-2009, 16:03   #38
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I just spoke with the people from Lind who make the Toughbook DC/DC power supply and the rep said that this was not true and that at no point do their power supplies invert to AC he quoted a %90 efficiency.

DC Power Adapters for Panasonic Computers first product in list
I've never heard of a way to make a higher voltage DC from DC without some sort of a pumping circuit, which means AC in the middle somewhere. I'm always open to learn new things, but I can't picture how you would induce the electrons to climb further uphill from a constant flow.

DC to DC converter - Wikipedia, the free encyclopedia

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Old 31-12-2009, 18:48   #39
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Here is a switched capacitor based pumping circuit--not really AC. You charge up a capacitor, then switch to put it in series with the input, doubling the input voltage.

http://www.ent.ohiou.edu/~starzyk/ne...ChargePump.pdf
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Old 31-12-2009, 21:59   #40
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You can argue that a DC-to-DC converter uses "pulsed DC" not AC in the conversion stage, but that's just semantics. Technically, AC is a waveform that goes positive and negative where a pulsed DC (or pulse width modulated DC, PWM) rises an falls from zero to a positive value.

But no matter how you slice it, the only question is "what do you reference as zero?" and from that point of view, pulsed DC is still an AC current. The dc-to-dc inverters still use a transformer, typically a ring with two sets of windings on it instead of the conventional "brick" transformer, and whenever you use a transformer there are losses.

The rep says they don't use AC, technically that's probably true. That's the difference between pork and chicken--it's just "the other white meat". All still meat.
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Old 01-01-2010, 07:34   #41
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A 20-watt solar panel would probably be rated at 16 or 17V so it might be only a 2.5A output.
Where can I buy that such solar panel? Here in Oz our 20-watt solar panel at 17V can produce only a miserable 1.176A output.
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Old 01-01-2010, 09:38   #42
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Chala-
A month after that was posted, I have no idea but I suspect it was a typo that dropped 2.5Ah into 2.5A, or the "it" I was referring to wasn't a panel. Dunno, but the bottom line is still that one 20W rated panel won't do the job. How many do you think he'd need?
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Old 01-01-2010, 10:54   #43
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Chala-
A month after that was posted, I have no idea but I suspect it was a typo that dropped 2.5Ah into 2.5A, or the "it" I was referring to wasn't a panel. Dunno, but the bottom line is still that one 20W rated panel won't do the job. How many do you think he'd need?
I am thinking now I might get an 80 watt solar panel, I bought an outboard with a 12 Amp alternator, and I have a 150 ah battery bank. Should that do the trick?
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Old 01-01-2010, 12:18   #44
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A garmin 440 ($400 0n Ebay) needs a maximum of 15 watts at 13.8 volts, and cruises at about half that. It is waterproof, much easier to see in sunlight, and easily integrates with a DSC radio and an AIS receiver. It has a complete set of very good US Coastal nautical charts preloaded, that are very easily updated on a regular cycle. and it can run an autopilot.

For me, the very best feature of this little treasure is its ability to recieve and plot a wide spectrum of weather information, that partially fills in for a radar when one is not practical or affordable. XM weather has rescued me from several bad situations already. I carry a laptop, but for serious navigation when the boat is at risk, I have the real thing.
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Old 01-01-2010, 15:15   #45
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OK OK I get it. Is the general consensus here that this is an impractical electrical/ navigation system? Would I be better off sinking the money into LEDs and a small chart plotter and doing away with my solar idea? Would just my 12amp alternator power a small plotter and said lights? I really hate the idea of plowing through aa batteries with a battery powered GPS. I don't think that is exactly the most socially responsible option.

I just had my heart set on bringing my laptop with me but maybe it is not the right fit for such a small boat.
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