Power consumption questions

[PH4555]

Morning all.
I am looking at the possibilities of taking my PC with me on a caravan stay 'off-grid'. I'm not clued up on the exact set-up, but the caravan has been fitted with a sizeable solar panel array on its roof (I think they are 250W panels) and "MPPT" which apparently can run everything you throw at it with ease. Apparently the batteries have been changed from 'standard' ones to Lithium which are more suited. Being a bit of a cynical sort, I have doubts about these claims.

Does anyone how much juice the following would use roughly?

-Tower PC, 650W PSU, i7-4770k, 16GB RAM, Nvidia GTX760. Rarely used for gaming these days, but watch a lot of 1080p video content.
-Dell 24" monitor.
-Huawei 4G router.
-Logitech desktop speakers
-USB mouse & keyboard.

I'm thinking of realistic scenarios where there's a few days of overcast/rainy weather and then on an evening have all that running, plus LED lighting in the caravan and maybe charging phone as well - seems to me like a lot of demand from a battery.

[Mr Pointy]

PC - probably 300W
Monitor - 20W
Router - 5W

Do you have to take a tower PC & all the peripherals? What about a TV, a tablet & a Chromecast dongle?

[PH4555]

Mr Pointy said:

PC - probably 300W
Monitor - 20W
Router - 5W

Do you have to take a tower PC & all the peripherals? What about a TV, a tablet & a Chromecast dongle?

Thanks for the numbers. Don't have any of that other stuff. Could borrow a 15" laptop if it doesn't work.

If I recall correctly there are 500W of solar panels and the batteries are 300 AH. Does that help to work out the viability ?

[TonyRPH]

PH4555 said:

Thanks for the numbers. Don't have any of that other stuff. Could borrow a 15" laptop if it doesn't work.

If I recall correctly there are 500W of solar panels and the batteries are 300 AH. Does that help to work out the viability ?

The will be some losses when the DC from the solar panels is converted to AC by an inverter.

Battery drain is non linear - so it's not a simple case of calculating 'X' watts from 'Y' AH.

You would be better off with a laptop or tablet (one that could drive your monitor for example).

[Griffith4ever]

PH4555 said:

Thanks for the numbers. Don't have any of that other stuff. Could borrow a 15" laptop if it doesn't work.

If I recall correctly there are 500W of solar panels and the batteries are 300 AH. Does that help to work out the viability ?

300Ah of batteries is significant, even more so if they are lithium - there is a LOT of money in batteries there.
500W of solar is also significant.

Weather permitting - i.e. not week after week of rain, or, grey winter days, you should have oodles of power. A laptop will not struggle at all, even with an external monitor.

A PC might be a bit thirsty, and in poor weather chew through the 300AH battery fast. They are not really designed for power efficience, whereas laptops almost always are.

To give you an idea of scale. A 40w fridge, which is on around 3/rds the time due to the thermostat, will run of an 85AH battery for 2 whole days. Unassisted. With 100w of solar this suddenly becomes infinite - in average British summer weather.

You are looking at perhaps 300w of "always on whilst you are working" power , which is a fair chunk. About 11 times more power consumption than the fridge, but then it'll be off overnight, so maybe about 7 times the consumption. AND .. you'll have 500w of solar.

I reckon you'll be alright, particularly if you set up power management properly on the PC. Have it manage processor power, and go into sleep mode swiftly, and then hibernate not long after. My PC wakes from hibernate in moments . Make sure you use an SSD not HDD to save a lot of power, and have fast wake-up and reboot times.

Edited by Griffith4ever on Thursday 24th June 13:10

[595Heaven]

Shame you missed out on the ACEPC mini PC deals on Prime Day. They are tiny, and come with a VESA mounting plate so could be mounted on the back of the monitor to save space. Power supply is c. 20W so a significant saving over taking the tower.

Start at about £150, but higher specced (processor, RAM, storage) would be closer to £200 or more.

https://www.amazon.co.uk/stores/Mini+PC+-Easy+life...

[Zoon]

I have an 115Ah battery that will run a 130W TV for around five hours with no additional solar going in.
However that is based on lead acid so I can only use 57.5Ah, as you have 300Ah of lithium battery you can effectively use all of it.

Based on my crude calculations you should be able to run the kit in question for ten hours in complete darkness.
Obviously any solar generation provided by the panels will extend this significantly.

[zarlak]

595Heaven said:

Shame you missed out on the ACEPC mini PC deals on Prime Day. They are tiny, and come with a VESA mounting plate so could be mounted on the back of the monitor to save space. Power supply is c. 20W so a significant saving over taking the tower.

Start at about £150, but higher specced (processor, RAM, storage) would be closer to £200 or more.

https://www.amazon.co.uk/stores/Mini+PC+-Easy+life...

Or a tiny pc pen drive: https://www.onbuy.com/gb/uk-windows-10-mini-pc-w5-...

[CarCrazyDad]

Mr Pointy said:

PC - probably 300W
Monitor - 20W
Router - 5W

Do you have to take a tower PC & all the peripherals? What about a TV, a tablet & a Chromecast dongle?

I would think the PC would use substantially less power than that.

I reckon peak load (while gaming) would be approx 250-300w but general load while browsing the web and watching things like Youtube would be much closer to 100w or even lower.

I would advise changing the desktop computer to a new AMD 5000 series (I think that's what it is) powered Laptop, they can work for 15-20 hours on battery alone , very power efficient compared to Intel offerings these days, and if you want some gaming capability get one with a 3060/3070 on board.
You can still easily output to any monitor you want but gives you an uplift in performance, efficiency and portability .

Sure the initial cost is going to be a lot (£1500 or more) but you'll get a few hundred quid for your old computer easily.

[cobra kid]

Phones and PC. so an off the grid lite then?

[PH4555]

Thanks all. Griffitfh4ever your post is particularly helpful. It's a new house build so basically moving into a tourer til we can get utils rerouted and up and running. Will be 'off-grid' but access to water. I don't want to be selling/replacing any of my existing kit and the set-up is just fine for my needs in the house, hence wanting to know the viability of whether it will work off the solar set-up . Never done anything like this before so quite excited to see it all work off free renewable energy aka the sun !

[PH4555]

Hi folks, me again . Numerous delays due to the "covids" with people not working has resulted in delays to this happening. I've since found out that it's 3x 160W panels so 480W total and only a single 200AH lithium battery. I'd had a few people say that in a good sunny summer there'd be enough juice to power the PC and peripherals for most of the da/ynight + other low power electrical stuff in the van, but a week of rain or just general overcast skies would likely run out of power.

There are a few options available to me. 1. is increase the capacity on the van, but this is least favourite as it's not mine and "should" only be a temporary arrangement. 2. is to buy a genny. 3. is to change to a lower power set up (earlier suggested in the comments above).

I am looking at the 3rd option. I have to confess my understandings of all things electricity and power related is limited beyond the basics. If a program, process or playing a game requires x amount of power, does it make any difference what is being used to power it? Would they still use the same amount of power regardless of whether it's powered by a desktop gaming PC via inverter, laptop via mains charger/inverter or even something like Minis Forum mini PC running directly on DC? I've been told that you'd use less power running directly on DC to the batteries rather than on 240V through an inverter. ?
These mini PCs seem to be 19V though, and it's a 12V system in the van so is that a no go? Would the system need to be 24V or higher for this to work?


Edit to add : wondering if something like this would do the job far better? Seems to have impressing power usage and can handle running games at perfectly acceptable FPS if needed :

https://www.guru3d.com/articles-pages/minisforum-h...
https://www.youtube.com/watch?v=LOLWCWHSDEA&ab...

Edited by PH4555 on Friday 13th August 07:27

[dapprman]

One question. How will the battery be charged? If this is by the solar panels then you may have issues. If not then day time with enough sun you should be fine.

To give you an idea of usage, at present based on a full house solar installation, with freezer, fridge, router, couple of NAS (both on tick over) LCD TV and a far higher end gaming PC running (though not playing an intensive game), and the usual other things you have in a house sipping power, I'm only using ~500W (I had a solar install about 6 months back and still tend to check the dashboard) so for being ok while under full solar you'll be fine.

Number of things to be aware of:

• Think on my best days I get ~10 hours of maximum power from my panels - but this is at the inverter, I have a couple more panels than I need, meaning that without these I'd probably only be at max for ~8.5-9 hours. My panels/front of house are west looking so in a very good position for the arc of the sun - you will need to make sure your caravan panels are positioned in the same way. Once the sun moves too far round or if the clouds are too strong you will be generating less, then none.
• While only short bursts, boil a kettle or use a microwave and you're straight on to the battery. I'm assuming your kettle will be a smaller travel one which uses a lot less power, not a big house hold one like mine which runs at 3 kW.
• Do you have a generator for backup? A friend of mine lived on a canal barge for 4-5 years, he installed solar panels and a battery (no clue what sizes though), however he still had to charge his battery from the barge motors every day (and these had to be turned off by a certain time - think 10 pm).

Edited by dapprman on Friday 13th August 10:24

[Griffith4ever]

PH4555 said:

Hi folks, me again . Numerous delays due to the "covids" with people not working has resulted in delays to this happening. I've since found out that it's 3x 160W panels so 480W total and only a single 200AH lithium battery. I'd had a few people say that in a good sunny summer there'd be enough juice to power the PC and peripherals for most of the da/ynight + other low power electrical stuff in the van, but a week of rain or just general overcast skies would likely run out of power.

There are a few options available to me. 1. is increase the capacity on the van, but this is least favourite as it's not mine and "should" only be a temporary arrangement. 2. is to buy a genny. 3. is to change to a lower power set up (earlier suggested in the comments above).

I am looking at the 3rd option. I have to confess my understandings of all things electricity and power related is limited beyond the basics. If a program, process or playing a game requires x amount of power, does it make any difference what is being used to power it? Would they still use the same amount of power regardless of whether it's powered by a desktop gaming PC via inverter, laptop via mains charger/inverter or even something like Minis Forum mini PC running directly on DC? I've been told that you'd use less power running directly on DC to the batteries rather than on 240V through an inverter. ?
These mini PCs seem to be 19V though, and it's a 12V system in the van so is that a no go? Would the system need to be 24V or higher for this to work?


Edit to add : wondering if something like this would do the job far better? Seems to have impressing power usage and can handle running games at perfectly acceptable FPS if needed :

https://www.guru3d.com/articles-pages/minisforum-h...
https://www.youtube.com/watch?v=LOLWCWHSDEA&ab...

Edited by PH4555 on Friday 13th August 07:27

Power is power, watts are watts. That's why we use watts to talk about power consumption, because regardless of the voltage, watts will always be the same.

What you've been referred to is the fact inverters (converting 12v to 240v) are slightly inneficient. Some power is lost in the conversion process. Thing is, if you are inverting a healthy amount of power, the loss is so small as to be fairly ignorable, particularly with good quality inverters.

[CarCrazyDad]

I was watching Linus Tech Tips recently and they outfitted a boat with some Solar Panels and large batteries.

May be an option, it also seemed very easy to set up.

[biggiles]

You will probably have plenty of power on tap, but I'd suggest getting a laptop. Then you are always in control of power consumption (i.e. you can unplug if the caravan gets low), and know how much battery time you have left. Modern laptops often have 4-8 hours of battery life.

And if you are doing a building project, you can take it with you on site.

[anonymous-user]

We have 360w of solar and 220ah of lithium batteries. Everything in our van has been made to be as efficient as possible so the fridge is 12v compressor, lights are all led. The only thing we use 230v for is my partner’s laptop which although much more efficient than a desktop it is a very high spec i9 and she mainly does photo editing. We could make it more efficient still by using a 12v charger for the laptop but haven’t found a need for it. I use a VictronConnect smart shunt to monitor the power level of the batteries and since being in the van full time since April we’ve never been below 91%.

I’m sure winter will be a different story but I’m sure you’ll be ok. Either way with that level of solar you could probably afford to add another battery and still have the performance to charge them. I say afford, it’d cost a fair bit!

[PH4555]

Thanks all again. Don't want to go down the laptop route. I seem to attract dust and fluff like a bloody magnet and past experiences with laptops has resulted in them being rendered useless after a couple of years due to getting clogged up with dust and cooking themselves. Nigh-on impossible to clear them out properly without disassembling it into 3000 bits and high risk of snapping fragile plastic retaining clips from being hamfisted.

Aside from this, I work on large wide spreadsheets which require min 24" screen at a comfortable resolution and distance to read the text. I realise that laptops have connectivity for external monitors, keyboards, mice etc but it's an overly complicated way of doing it.

I think a DC mini PC is going to win this battle. I can sell my comparatively power-hungry tower PC and replace it with this whilst keeping the peripherals. The only downside is that I'll still need an inverter to run my monitor and the 4G router but I can live with that.

I am thinking of buying a back-up genny too but no point wasting money on that until I see if the solar power is going to cut it or not.

[omniflow]

PH4555 said:

Thanks all again. Don't want to go down the laptop route. I seem to attract dust and fluff like a bloody magnet and past experiences with laptops has resulted in them being rendered useless after a couple of years due to getting clogged up with dust and cooking themselves. Nigh-on impossible to clear them out properly without disassembling it into 3000 bits and high risk of snapping fragile plastic retaining clips from being hamfisted.

Aside from this, I work on large wide spreadsheets which require min 24" screen at a comfortable resolution and distance to read the text. I realise that laptops have connectivity for external monitors, keyboards, mice etc but it's an overly complicated way of doing it.

I think a DC mini PC is going to win this battle. I can sell my comparatively power-hungry tower PC and replace it with this whilst keeping the peripherals. The only downside is that I'll still need an inverter to run my monitor and the 4G router but I can live with that.

I am thinking of buying a back-up genny too but no point wasting money on that until I see if the solar power is going to cut it or not.

Essentially you've got 2 options:

1. Consume less power
2. Add more power to the ecosystem

A laptop will consume less power than a desktop
A generator will add more power to the ecosystem

A generator will be noisy, inconvenient, have a purchase cost and running costs
A laptop will be relatively silent and convenient, but will have a purchase cost and is less upgradable than a desktop so will have a comparatively shorter lifespan - but if you buy something decent at the outset, it should last 5 years without issue.

Connecting an external monitor to a laptop is really not complicated - it's 2021 - and it's been straightforward for the past 20+ years. Same with keyboards and mice - really not hard (or complicated). With a modern laptop, a single USB-C cable is all you need - keyboard and mouse then plug into the monitor.

Buying a mini-tower desktop (or whatever small form factor PC you're looking at) really is a dinosaur way of looking at this problem - and you still run the risk of it overheating if you try to cram too much into it.

[Lucas Ayde]

One of those USB-C powered external screens might be ideal with a laptop that's going to be used for more than just light work on the go. Combined with the laptop screen you've got a dual monitor setup (albeit small screens).

Also a decent external keyboard and mouse goes a long way to making a laptop easier to use.