Working from the boat - laptop charging

Doesn't this scheme rely on having substantially charged domestic batteries available at the time required ? So for a boat on a mooring attention needs to be given to that aspect.If the weekend becomes four days there will be increased draw generally.
 
Yes, or a small solar installation or wind gen. it’s really not much power. While under light use its 0.5A from a 12v system
 
150W of solar was not enough for working at anchor last year, they are blown out semi flex panels though and I do software dev which is a bit power hungry at times. I am planning on fitting a 490W proper glass one. You can get decent USB C car sockets that will kick out 90W.
 
Yes, of course my 150WH figure was purely the laptop for 8 hours. The reality is you'd probably use other things like lights and stereo, and possibly use the laptop or a tablet for entertainment in the evening. I've got 200W of panels for this year and I expect that to just stem the flow to give me a few good days away from power. I'm not even planning to permanently mount them I'll have an Anderson connector in the cockpit locker ready to deploy them once anchored.
 
Plus one for Powerbanks - if you get the right one it can also be used to start the boat engine I guess? I say this as I have one in the car I use but have never tried on a boat diesel.
 
Haven't read all the comments, so before anyone shoots me down for sending the same reply as someone else - sorry!

We had exactly this situation, and I could not for the life of me get my head around converting AC to DC (shore-power, solar, etc to boat batteries), to AC ( via inverter for laptop charger plug), then back to DC again for the laptop. This losses involved in each step of this equation are crazy.

We still have our mains laptop charger for use when on shore power, but bought a 100W DC (12-19V) laptop power supply off Amazon which works great. Cost around £35-40 and works a treat. It has multiple adaptors for different laptops (if that is an issue for you). I was a bit sceptical of how secure these would be but they are absolutely fine. The inline transformer also does not get as hot as the AC one which I also find reassuring.

You just need to make sure you have the sufficient fuse rating in the wiring for your 12V socket, but it's an easy install. We use the laptop with OpenCPN as an additional nav source and it hasn't been a significant drain on the boat's batteries during 5hr sails (in the short window we were able to use the boat last year)
 
scruff said:
May be a bit on the pricey side, but my work laptop is a dell. If spending £50 means my I don't have to go to my boss / IT after frying my laptop whilst working from the boat , using a cheap random e-bay brand adapter, it may be money well spent!
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Indeed, having worked in IT support I can confirm Dell are perfectly capable of frying your components with their expensive accessories! In their defense though, they never quible about why the hardwear is dead, they just swap out the bits and get you working
 
Moodysailor said:
I did - the adaptor I bought has multiple ends but doesn't have USB-C so I didn't link it. I assumed everyone knows about Google by now :ROFLMAO:
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USB-C isn't just an end, it's a standard which includes various gubbins to charge devices. As such you can't just fit a USB-C plug and have it deliver high power, the system would self limit to protect itself and probably default to 5v 2.1W mode. To charge USB-C you need something supporting the PD spec which will negotiate higher power levels properly. You also need a cable which supports it, not all do.
 
lustyd said:
USB-C isn't just an end, it's a standard which includes various gubbins to charge devices. As such you can't just fit a USB-C plug and have it deliver high power, the system would self limit to protect itself and probably default to 5v 2.1W mode. To charge USB-C you need something supporting the PD spec which will negotiate higher power levels properly. You also need a cable which supports it, not all do.
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True, and there are options out there to support that. A quick search shows a number of possible options on 12V DC-DC laptop chargers - exactly what I said I had - with USB-C from £20 to £100. I just bought a powered USB-C hub (as amongst other things we have an extra screen and USB inputs and wanted to not have to unplug multiple devices each time we move the laptop) as our power supply can power that or the laptop directly simply by changing the tip.

There are a few ways to solve the problem, I was just offering one. And did read the first post ;)
 
It's worth being a bit numerate about the average power required by a laptop over a (say) 10 hour day. My MacBook Pro consumes about 5 - 7W on average (call it 6), so about 7 - 10 hours continuous use on one full charge. Averaged over 24 hours that's 60 Whrs or 5 amp-hours per 24 hrs from the 12V battery.

This is really quite small - the heater or the fridge are at least 10x this. So by all means pay attention to efficiency, but the difference between the most efficient and least efficient solutions are likely to be slight.

Most efficient possible: A 12V -> laptop charger (lap top specific and can't be used by anything else) maybe 92% efficient, so one wastes 5 x (1 - 0.92) / 0.92 = 0.43 amp-hours a day.

Less efficient: An inverter and the existing laptop charger (the inverter can be used for many other purposes) is 92% efficient for the inverter plus 92% for the charger, hence 85% overall (0.922). That wastes 5 x (1 - 0.85) / 0.85 = 0.88 Ah per day.

The difference is 0.88 - 0.43 = 0.45, ie less than half an amp-hour a day. It's for the OP to decide if this, to my mind marginal, difference justifies the purchase of a special charger or whether an inverter could be the more pragmatic solution. With an inverter other computers, or a printer/scanner for instance, can be powered: it's what I do when working from the boat.

BTW, if the lap-top is at all modern - and the OPs will be if he's to use it for work - its power brick will not be like a terrible old Dell or IBM one and thus be sensitive to waveform. It will be quite happy with fairly low cost inverters.
 
Those inverter figures need adjusting to take into account the fact that there is an overhead with an oinverter, even if it isn't connected to anything. So while a laptop might be plugged in and fully charged there could be an overhead of anything up to an amp, just for having the inverter on. For every hour it's on and doing nothing, that's an amp hour, so forget the "less than half an amp hour a day" claim.
 
PaulRainbow said:
Those inverter figures need adjusting to take into account the fact that there is an overhead with an oinverter, even if it isn't connected to anything. So while a laptop might be plugged in and fully charged there could be an overhead of anything up to an amp, just for having the inverter on. For every hour it's on and doing nothing, that's an amp hour, so forget the "less than half an amp hour a day" claim.
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Well, if you (i) have such a model which takes loads of current, and (ii) you forget to turn it off. But the same can be said for the 12V - lap-top charger: one can equally leave that on all day even if not using it; what makes it any less likely than an inverter to consume excessive power when not loaded?

To look at the specs of a real inverter, I've just looked at amazon, and the even cheapest has a no-load current less than 300mA.
 
jdc said:
what makes it any less likely than an inverter to consume excessive power when not loaded?
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just for the record the one I posted uses effectively zero when not in use (aka plugged in to a device). Obviously the LED voltage display consumes a tiny amount, but the Victron battery monitor isn't able to detect it.
 
lustyd said:
just for the record the one I posted uses effectively zero when not in use (aka plugged in to a device). Obviously the LED voltage display consumes a tiny amount, but the Victron battery monitor isn't able to detect it.
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Indeed - most good stuff actually consumes rather little when not loaded. Your laptop charger and my inverter both don't register on the battery monitor when unloaded.

I'm sure there is cheap stuff out there which burns excess power when not loaded, so it's a useful reminder to check the details but it appears not to be a universal issue.
 
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