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DrWatson

On board inverter, how small is too small?

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Pure sign hands down. As IT stated the inverters aren't efficient apart from a somewhat narrow band, DC-DC's are good but limited. If you have a fairly good idea of what you want to run then size the inverter for this in it's peak band

 

https://www.victronenergy.com/upload/documents/Output-rating-operating-temperature-and-efficiency.pdf

 

In this document you can see that if you wanted 400-1600w of load and have 90%+ efficiency you'd be looking at the 3000va units. DC-DC converters top out at 98% for the expensive super duper ones

 

 

Really comes down to what exactly you are planning to power.

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A couple of extra solar panels are much quieter than a wind gen, no moving parts either. Another way is to have a belt driven alternator running off your prop shaft.

Alternators won't start to produce power below 2000rpm so work out your pulley ratio. Wind gennys are great when a cyclone is about, all other times a lot of noise and nothing at the other end so SPs are the way to go and good storage for rainy days.

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Most laptops require 19v DC to run (chip set and CPU power) and as others have stated, the best 12v DC conversion is to run a simple switch mode power supply to get 12v to 19v. Inverters be it pure since wave or square won't create a problem when using a laptops 240v power supply as the filtering is able to handle the ripple but if you are power conscious, go a direct DC to DC converter. Basically it's a oscillator stepping 12v up to 19v using a transformer so better conversion than inverter and converting down.

The Chinese are now producing laptops that are true 12v. However the wattage will probably be the same as a 19v unit (more amps) so no real gain.

We have gone down this road and there are now USB (5V) PCs available that have dual processors and capable of 1080p HD resolution. They have USB ports so mouse and keyboard can be plugged in and externally powered hard drives run OK. All you do is plug them directly into a HDMI port on a monitor and there are 12v monitors about that can run these. 2ah!

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So, We've gone Jon's way, and got a smaller supply just for charging the myriad small devices and will get a larger one later. Reasoning is this: 

  • The macbook pro is a bugger to find a decent 12v charging solution for and I'm not upgrading my Mac because it's already kick arse and supposed to last me another 4-5y.
  • The small inverter, although less efficient, also allows me to charge a bunch of other different things with different voltages, that a fixed DC-DC converter doesn't. So I only have to buy one item, and not a number of items and given the state of the bank balances at this moment, that's a good thing.
  • The prospective wind generator is intended for longer voyages - yes I know they're noisy.
  • We will also get a 100W Solbian "flying" panel, to position optimally when the sun is out for additional power; weighs only 2kg.
  • I have battery powered power tools, that can be charged from it. 
  • It's small enough that I won't be tempted to try to run my big powertools from it. 
  • It's large enough that I can run this and save a bit on bottled gas.
  • bialetti_moka_electric_standard_1.jpg

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Guest 000

The Dutch take their coffee very seriously which is why I am not letting Joke see the pic of your espresso pot. Have looked online for wattage info but without success. But producing heat takes mega amps from your battery - can your system afford it?

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You’ll find, DrW, that 160amp hours is small. IMO. We use about 150amp hours every 24 hours on average. I know lithium is easier, faster charge rate etc, but you still have to put it back in!

What’s the engine?

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Yea, I actually want to double it to 320, but had trouble convincing the yard and my bank balance Engine is d1 4. Standard alternator, so I’m still looking for more charging. At least with the Li a short period of higher current load won’t kill it.

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