Electricity Consumption Questions

[Paul C]

1 hour ago, Pennine said:

My solution to the same dilemma was an Acer Revo One RL85, sadly no longer made. It has Intel Core i5, 8Gb Ram, 240 Gb SSD, 2 x 1TB HD, and all in a box 4in x 4in x 6in. Needs 19v dc (PC is 65w, so about 3.5amps) which is provided by a brick from 12v Dc. Never had any issues with voltage spikes. It has HDMI into a Samsung 27in monitor, also supplied via 19v/12v brick. I would suggest investigating Mini/micro PCs to find one to suit your needs. There are plenty models available out there.

Plenty of laptops will do that now. I'm not sure how much of an advantage a laptop + mouse + external monitor will offer over the above kind of PC, it would be 3 parts instead of 4 (ie no need for another keyboard) AND the laptop's own screen may be able to function as a 2nd screen adding screen area for some jobs?

[WotEver]

2 hours ago, Peter009 said:

We have a Victron 3000 inverter

A good inverter that will supply all that you are likely to require on a boat. 

2 hours ago, Peter009 said:

we have 5 batteries and one dedicated for the engine I really do not know what capacity we have

So 4 domestic batteries. Likely to be 120Ah each, giving you a maximum usable capacity (when they’re new) of around 240Ah. If you are using power from the batteries for 12 hours a day then that gives an average current draw of 20A at 12V, which is a draw of about 200W on average. Not a huge amount. 

 

If you did this then once you've used that energy you shouldn't draw another drop of electricity until the batteries are recharged. 

 

The above demonstrates why posters have been asking you where your electric will be coming from. Every drop you use has to be replaced, plus 10-20% more, and it must be replaced as soon as possible. It’s unlikely that you will be able to work whilst cruising, so the source of your electricity needs to be the focus of your attention far more than “how many sockets should I have?”

[Tony Brooks]

2 hours ago, Peter009 said:

Thanks Alan would love to but we are moving the boat in 5 weeks to the canals and need all the money we have for that due to cranes etc maybe one day but I think we will not have some money for some time so will have to make do until then

I think you may not be putting enough effort into getting the recharging right. This is vital otherwise you will be constantly buying batteries. You need to FULLY recharge batteries at least once a week and the more frequently the better. You should recharge to 80% or more every day. How is up to you but the engine alternator will only average about half its rated output over two to four hours and the longer you keep charging the lower the average. Solar rules but gives little in the winter.

[Peter009]

25 minutes ago, Tony Brooks said:

I think you may not be putting enough effort into getting the recharging right. This is vital otherwise you will be constantly buying batteries. You need to FULLY recharge batteries at least once a week and the more frequently the better. You should recharge to 80% or more every day. How is up to you but the engine alternator will only average about half its rated output over two to four hours and the longer you keep charging the lower the average. Solar rules but gives little in the winter.

Hi Tony the inverter is set to charge only so is always charging the batteries at least that is my understanding.  

[Alan de Enfield]

6 minutes ago, Peter009 said:

Hi Tony the inverter is set to charge only so is always charging the batteries at least that is my understanding.  

It will only charge the batteries when you are connected to a mains land line.

 

Presumably this is a 'combi' (both battery charger and inverter)

If you are trying to charge your batteries via the inverter, then you are discharging the batteries to power the battery charger to charge the batteries. 

As this is a very inefficient in power terms, you will actually be using more power than you are replacing so the longer you leave the charger connected, the quicker you will flatten your batteries.

 

Imagine a bucket with a hole in it, you catch the water leaking out and put it back into the bucket but spill a little every time, eventually the bucket will be empty.

Edited April 6, 2019 by Alan de Enfield

[Tony Brooks]

7 minutes ago, Peter009 said:

Hi Tony the inverter is set to charge only so is always charging the batteries at least that is my understanding.  

not unless it is always attached to a shoreline or mains generator its not. It won't be when you are out cruising and when you arr you need to set it to invert only (no charging).

[MtB]

5 hours ago, Peter009 said:

Hi Tony the inverter is set to charge only so is always charging the batteries at least that is my understanding.  

 

This is false understanding. It won't. It will only be charging the batteries when you are connected to a shoreline.

 

When you are actually cruising the alternator will be charging the batteries. When you are moored up off grid your four 110AH domestic batteries will no be being charged. 

 

When moored up with engine OFF your batts when new, will be flat with 11 hours of computer use, working with WotEver's estimate of current consumption. Fully re-charging the batts to 100% will take about 12 hour of engine running. You can only run your engine between 8am and 8pm when moored up and even this will piss off anyone moored nearby. 

 

This is why we are pressing you properly to consider and learn about how you are going to generate electricity when you are out and about, and working on the PC at the same time. We fear you are about to wreck the batteries really quickly then you'll be unable to work other than by returning to the marina and shoreline.

 

The performance of your (probably cheapo) batteries will degrade very fast if you fail to recharge them well and regularly as described by by Tony in post 28. Even then, cheapo batts still degrade quite quickly in my personal experience as it is very difficult to NEVER abuse them, even once. 

 

 

 

 

Edited April 6, 2019 by Mike the Boilerman

[dmr]

There are 12 volt desktop PCs available but its likely cheaper to use a 240volt PC and an inverter, and only a bit less efficient.

 

Laptops make a lot of sense on a boat, its a small space and laptops take up less space. The big thing though is that power consumption will always be a significant factor when designing a laptop, but will be of much lower priority when designing a desktop. Unless you are designing hardware and need to plug things into a PC bus, or are using very esoteric peripherals, its hard to see why a laptop won't do the job.

 

..............Dave

[mrsmelly]

Just a quick bit of advice. If you are still at the planning stage ensure you have plenty of mains sockets throughout the boat. Funny thing is many boaters have a couple each end of their boat and a couple in the middle but ask how many they have in their houses and they have loads in every room. If you are going to full time live aboard make life easier from inception. For instance we have 8 sockets in the front cabin, 2 at the dinette, 8 in the kitchen, 6 in the bedroom and 4 in the utility room. I have removed another 6 when fitting a stove during my ownership. Living aboard is completely different to hobby boating and the boat needs fitting to suit its purpose.

[LadyG]

Oh dear.

I hate to ask, but why did you decide a boat was a good idea? There must have been plenty of motivation?

Edited April 6, 2019 by LadyG

[WotEver]

52 minutes ago, Mike the Boilerman said:

This is why we are pressing you properly to consider and learn about how you are going to generate electricity when you are out and about, and working on the PC at the same time. We fear you are about to wreck the batteries really quickly then you'll be unable to work other than by returning to the marina and shoreline.

Perhaps it would be good for OP to read this post:

 

[MtB]

1 minute ago, WotEver said:

Perhaps it would be good for OP to read this post:

 

That is a very good article. You could learn a lot from it!

 

 

 

[WotEver]

2 minutes ago, Mike the Boilerman said:

 

That is a very good article. You could learn a lot from it!

 

I’ll have to give it a read some time. 

[MtB]

2 minutes ago, WotEver said:

I’ll have to give it a read some time. 

 

More seriously, I think a fiercely abridged version might be useful too. Newbie boaters (e.g. the OP) I think are inclined to see battery charging as a minor and peripheral thing, trivial and secondary to the big stuff like engines and bathrooms gas systems, and not worth spending much time and effort on in comparison. After all how hard can it be? A car charges its battery no problem with an alternator, same as the boat engine has. No further thought required, plenty of bigger stuff demanding their attention. I certainly tended to this point of view when I first started boating. 

 

A short and concise pre-primer explaining why people need to read your main primer...

[WotEver]

13 minutes ago, Mike the Boilerman said:

A short and concise pre-primer explaining why people need to read your main primer...

Not a bad idea. I’ll give it some thought when I’m less tired

[mrsmelly]

13 hours ago, Mike the Boilerman said:

 

More seriously, I think a fiercely abridged version might be useful too. Newbie boaters (e.g. the OP) I think are inclined to see battery charging as a minor and peripheral thing, trivial and secondary to the big stuff like engines and bathrooms gas systems, and not worth spending much time and effort on in comparison. After all how hard can it be? A car charges its battery no problem with an alternator, same as the boat engine has. No further thought required, plenty of bigger stuff demanding their attention. I certainly tended to this point of view when I first started boating. 

 

A short and concise pre-primer explaining why people need to read your main primer...

All very true. I remember our first liveaboard, before the era of inverters etc. It had a hand start engine only and one 12 volt battery charged from a small lucas alternater via the small lister engine. The black and white 12 volt telly picture used to get smaller as the battery capacity dropped until it went of as the battery was flat. We thought that was the norm so watched telly till it went off and charged the battery, or not!! the next day ish.

[Dr Bob]

On 06/04/2019 at 03:41, Peter009 said:

 

....... but am wondering whether anybody out there is actually using a mains PC not a laptop using some sort of adaptor for 12V and am not even sure if that is possible.  I am not that worried about it as when not on shore power we would not be using the main PC which is mains power but if there is an option to set up a PC to 12 volt I would be really interested to know about it.  In the future we would like to get a generator and solar but don't have the money for it yet.

 

On 06/04/2019 at 13:14, Peter009 said:

  We intend to cruise a lot, maybe not on shore power all the time it is those times when we are not on shore power that concerns me and we may get a generator at some point as that could also be a solution, the nature of my work does involve graphics a lot so I do tend to use a lot of computing and monitors.  

So are you looking to use your desk top when not on shore power? You sound confused!

- First, you must do what you have been advised and do a power audit. How much power per day are you going to use? How much more is this desk top going to use?

Last year our batteries went down by about 100-130Ahrs each evening so that had to go back in the following day - or at least within a couple of days. Add a desk top to that and it could be 200Ahrs plus. The OP really needs to think about whether he can get that back in or look for a less power hungry option. MacBooks are pretty frugal on power and have great graphics capabilities.

Please work out what you think you are going to use each day. As someone above said, put a power meter on the desk top and see how much it uses.

If your inverter is on all day, then just plug your 240V devices into 240v.

- Once you have that figure, then work out if you can replace it as per the multiple threads above. Please, please do not bank on running an engine or genny all day. It is so annoying to the boats you park next to.

We managed to get our cheapo lead acids through 2 years and lost less than 10% of their capacity (so still 90%+ left) but that was with getting them back up to 100% (and they were full) at least every other day. We definitely could not have managed that if our 100-130Ahrs overnight useage went up to 200+Ahrs.