Down to 250kwh, but need help!

Steven Lake · August 2011

Ok, I'm trying to go to a completely off grid system (one, because power up here is rather unreliable and loves to go out regularly, and two, with the local power company raising prices to ridiculous rates due to the war on coal) to power my new house, but I'm currently sitting with a dilemma and figure you guys might be able to give me some ideas to help me make that last little push to get everything down as low as absolutely possible to allow me to go with as lean (and cheap) a system as possible.

Alright, here's my plan. I'm looking to trim my KWH per month as absolutely low as I can. 250kwh is my lowest number so far (my average floats much closer to 300kwh), and this is what I've gotten things down to so far with my usage reductions. IE, this is my usage after removing everything I could, leaving only the below list of electrical items I still have running in the house that use AC power.

Full time usage (>6hrs per day)
Refrigerator (Frigidare, freezer on top, basic model)
Small Fans (x3 for air circulation)
Desktop Computer (total load for entire rig: 175w max, on for 10-12hrs per day because I am a programmer and work from home)
Network gear (2 switches, 1 modem, 1 router, two UPS's 600va each)
(I have 2 more pc's, but their usage is negligible.)
Night Lights x2, on 24/7. 4w bulbs.

Intermittent or occasional usage (on as needed)
Lights (all have CF bulbs, used for a combined total of one hour per night, maybe two, as I prefer to work in the dark)
Television and media player (MP is in standby when not in use, both are used maybe twice a week for 2hrs tops)
Microwave (5 total minutes usage on average per day, 1500w)
Phone charging (3x's a week, 0.1amps)
Water pump (intermittent, as needed, no idea of actual usage, and no way to track it, so I have to guess, unit is 220v)

Cooling is done by natural means, and only requires the fans to keep the air from going stale. Heating is by wood burner (pot belly with peltier fan for circulation). Water heating, stove cooking, both done by gas. I also have a big 15cuft chest freezer that gets used for a few months every fall (pulls about 150kwh per month based on what I've found) so I'm needing enough breathing room to allow that to run during the fall around harvest time and during hunting season to allow us to store all the meat we bring in until we get it canned.

Well, that's all I can think of off the top of my head. What can I do with what I have here to further reduce my energy footprint in order to get my usage down as absolutely low as possible, allow a safety buffer within the system (ie, 3 days without sun as suggested before), and keep it to a reasonable cost?

Right now my usage WOULD NOT make my system viable. Well, not at the size I plan it to be. I'm hoping to get under the radar at 1200ah total capacity, and right now, if my math is right (I'm using the usage equation I found online for WH to AH of capacity required) then my current usage would require over 1300ah of battery capacity at 48v, which is way too high, as I'm shooting for a 1200ah system @ 12v, as anything bigger is too expensive. Oh, and btw, here's the equation I'm using. If it's wrong, please tell me, as it's the only one I have.

AH = (1.5 * 5 * Xwh) / Y volts
X=WH used per day
Y=Voltage of system.

My equation would look something like this:

AH = (1.5 x 5 x 8500 wh) / 12 volts = 5312.5
AH = (1.5 x 5 x 8500 wh) / 48 volts = 1328.125

Thus I think you see my problem. Of course, if my math is off, things might actually not be quite so bad. What baffles me the most is that I'm pulling WAY too many KWH and I can't figure out why. I'm suspect of the fridge, but at this point it could be just about anything. Ideas, suggestions? I'm really scratching my head here.

mikeo · August 2011

Re: Down to 250kwh, but need help!

Desktop Computer (total load for entire rig: 175w max, on for 10-12hrs per day because I am a programmer and work from home)

Look for a modern computer with low power CPU. You can probably do everything that you need for about 45 watts max with the monitor being the greatest draw. I run wireless, DSL modem and weather station on about 15 watts. My desktop is a 10 year old power hog, but I have a FIT PC Slim that draws about 6 watts with all the features of a desktop.

RCinFLA · August 2011

Re: Down to 250kwh, but need help!

What is too expensive for utility rate. You are going to spend $1 to 1.50 per kWH doing it off grid with batteries.

Don't even think about 12 v system for power you are talking about.

I suggest a hybrid inverter like XW6048 with at least 500 AH of 48 v batteries. It can run on grid when available and will act as immediate UPS switch over to batteries when grid goes down. You can suppliment with solar at later time.

Talking about $7k to $10k for starters.

Atom mini computers run about 20-30 watts. Best LED backlight monitor is 15-20 watts but you can put a short backlight timeout to cut the average down.

Cariboocoot · August 2011

Re: Down to 250kwh, but need help!

Let's try some simpler math; I can't handle the complicated stuff.

250 kW hours per month = 8.4 kW hours per day. That's pretty rough for off grid.

8.4 kW hours / 48 VDC = 175 Amp hours. For 25% DOD multiply by 4 = 700 Amp hour battery bank minimum. That gives you 25% of your battery to use and recharge daily, 25% extra in case the sun doesn't shine. If it doesn't shine on day 3 you start the generator.

To get loads down start by investigating that water pump. It probably doesn't run long per day, but a 240 VAC pump could be a big power consumer with a large start-up demand. It may be possible to change out for a smaller unit that doesn't consume so much, depending on what your well is.

Get rid of the desktop. 175 Watts isn't unusual for one, but a laptop with a 17" screen will use 150 Watts less.

Get a Kill-A-Watt and start measuring these things on a real Watt hours basis; don't rely on calculations from the labels. Some will be lower, some will be higher.

snuffy · August 2011

Re: Down to 250kwh, but need help!

I'd junk that freezer. 150 KWH a month is terrible. I have a 12 cubic footer that's 15 years old and it only draws 40 KWH a month (1.35 KW a day on a kill-a-watt meter) when it's in the 80's in the house in July.

waynefromnscanada · August 2011

Re: Down to 250kwh, but need help!

Cariboocoot wrote: »

Get rid of the desktop. 175 Watts isn't unusual for one, but a laptop with a 17" screen will use 150 Watts less.

My desktop was sucking back almost 200 watts and was killing my batteries, or would if I had let it, finally dumped it for a 15 inch laptop that only used 18 watts! Unfortunately it came with the infamous VISTA os that was constantly crashing, slowing down drastically and/or freezing, necessitating regular restarts and elevated blood pressure. Finally had enough and got a 17,5 LED with Windows 7 that uses just 20 watts and does everything the power sucking desk top did, except in one area - - the desktop sometimes crashed or froze, although nowhere near as much as the VISTA machine did. The 17.5 laptop with Windows 7, just doesn't crash, or freeze! Like that battery bunny, it just keeps on going and going. And at just 20 watts instead of 200!
And that freezer stinks! My new energy star uses less than 246 kwh/year! Now if I can only get that second, much older and power hungry freezer out in the shed, empty and get rid of it, I'll have tons of power to waste. Won't know what to do with it all.

BB. · August 2011

Re: Down to 250kwh, but need help!

One thing to watch with freezers is they do use a lot more power when you put "warm" items in (big moose) and bring down to freezing... You could easily use 2x the normal amount of power until everything is down to zero degrees.

-Bill

Cariboocoot · August 2011

Re: Down to 250kwh, but need help!

BB. wrote: »

One thing to watch with freezers is they do use a lot more power when you put "warm" items in (big moose) and bring down to freezing... You could easily use 2x the normal amount of power until everything is down to zero degrees.

-Bill

We do not have that problem in the Cariboo; up here the moose are pre-frozen from walking around in the -40C temps.

Of course, so are the hunters.

The one freezer I tested had pretty horrible power consumption; not much better than the OP's. I have two more to test when I get to them. One is a fairly modern upright unit.

Steven Lake · August 2011

Re: Down to 250kwh, but need help!

mikeo wrote: »

Look for a modern computer with low power CPU. You can probably do everything that you need for about 45 watts max with the monitor being the greatest draw. I run wireless, DSL modem and weather station on about 15 watts. My desktop is a 10 year old power hog, but I have a FIT PC Slim that draws about 6 watts with all the features of a desktop.

Well, I have been threatening to get a new PC for a while. I guess this is a good excuse to make that jump.

RCinFLA wrote: »

What is too expensive for utility rate. You are going to spend $1 to 1.50 per kWH doing it off grid with batteries.

Well, our current rate is 15c per KWH, but that's just the electricity. The company itself is hitting us with this fun little federally approved "special" fee that's been running around called the "Power supply cost adjustment". IE, they can't officially charge you 35c a KWH, so they do it through this secondary federal fee. It also doesn't help that our power comes from what the power company calls "A special power run". IE, a mile long extension off the main track that they make us pay for. No wonder we got the house so cheap. The nutjobs at the power company must have nearly bankrupted the previous owners.

Don't even think about 12 v system for power you are talking about.

Well, 12v was the setup I was looking at simply because that's where I got started in my research. ^_^;;

I suggest a hybrid inverter like XW6048 with at least 500 AH of 48 v batteries. It can run on grid when available and will act as immediate UPS switch over to batteries when grid goes down. You can suppliment with solar at later time.

Ya know, that's a pretty nifty idea. I like that.

Talking about $7k to $10k for starters.

Urgh. Yeah, I know. I'm trying to keep the entire system under $10k if possible. Hence my trying to get the footprint down as low as possible.

waynefromnscanada wrote: »

My desktop was sucking back almost 200 watts and was killing my batteries, or would if I had let it, finally dumped it for a 15 inch laptop that only used 18 watts! Unfortunately it came with the infamous VISTA os that was constantly crashing, slowing down drastically and/or freezing, necessitating regular restarts and elevated blood pressure. Finally had enough and got a 17,5 LED with Windows 7 that uses just 20 watts and does everything the power sucking desk top did, except in one area - - the desktop sometimes crashed or froze, although nowhere near as much as the VISTA machine did. The 17.5 laptop with Windows 7, just doesn't crash, or freeze! Like that battery bunny, it just keeps on going and going. And at just 20 watts instead of 200!
And that freezer stinks! My new energy star uses less than 246 kwh/year! Now if I can only get that second, much older and power hungry freezer out in the shed, empty and get rid of it, I'll have tons of power to waste. Won't know what to do with it all.

lol. I use Linux (Kubuntu distribution), so I don't get any crashes...ever.

As for the power hungriness of the freezer, I knew it was high. Thus why I don't use it anymore, save for those few periods as I can't do without it. Been threatening to replace it anyways, so I guess this is as good an excuse as any. Oddly, during the times it's turned off, I use it for storing paper towels.

Cariboocoot wrote: »

Let's try some simpler math; I can't handle the complicated stuff.

250 kW hours per month = 8.4 kW hours per day. That's pretty rough for off grid.

8.4 kW hours / 48 VDC = 175 Amp hours. For 25% DOD multiply by 4 = 700 Amp hour battery bank minimum. That gives you 25% of your battery to use and recharge daily, 25% extra in case the sun doesn't shine. If it doesn't shine on day 3 you start the generator.

That's interesting that you came to that. The equations I kept finding always pointed to a much higher AH usage for 8.4kwh.

To get loads down start by investigating that water pump. It probably doesn't run long per day, but a 240 VAC pump could be a big power consumer with a large start-up demand. It may be possible to change out for a smaller unit that doesn't consume so much, depending on what your well is.

The well is 120ft with a 10ft head. I've *thought* about the pump, but I never really figured it was possible to go lighter on it simply due to pressure and flow needs in the house. But I'll get it looked at and see if I can trim that down some.

The one freezer I tested had pretty horrible power consumption; not much better than the OP's. I have two more to test when I get to them. One is a fairly modern upright unit.

I'm wondering if it's got something to do with the sheer volume of the freezer. The one I have is a massive 15cuft freezer, so it's got a lot of work to do in order to keep stuff cool in there. If you were to find a way to compare it to an HVAC system as far as "tons of cooling", it'd have a pretty large cooling footprint. I'd love to go smaller, but it's a bit hard to fit several large deer and a side of beef into anything less than 15cuft. ^_^;;

jcgee88 · August 2011

Re: Down to 250kwh, but need help!

Steven Lake wrote: »

I'm trying to go to a completely off grid system .

Although you are asking for advice on how to further reduce your
monthly power usage, my question to you is, why do you want to
go off grid instead of doing a grid-tied system?

If you go off grid, you need to buy equipment for storage and
charging, you have to replace the batteries every few years,
and your solar power generation efficiency is cut in half. Let's
say that it costs $4000 (a guess) spread over ten years
for the extra equipment, maintenance, and loss power due to
charging/storage overhead.

If you remain on grid, I'm guessing your utility will charge you
some fees and taxes even if you use no power in a given month.
But, you gain back the loss in efficiency, you'd get a credit for
excess power you generated, and you'd have an emergency
backup. Let's say that it would cost you $15/month (that's
probably high) just to be connected to the grid without using
any of the utility's power.

If you do the math, the $4000 (you fill in your actual number)
gets you 10 years of service, but $4000 divided by $15 yields
22 years of equivalent service. Given that the $15/month is
probably high and my calculation ignores any interest you
might make by paying over time instead of up front, the 22
years might actually be 25-30 years.

You post asks how to reduce your current usage by 10-15%,
which can be accomplished perhaps by buying more efficient
appliances or spending money on other enhancements like
insulation, thermal windows, etc. My sense is that the decision
that needs to be made first is: does off grid make sense in
your case?

John

mike95490 · August 2011

Re: Down to 250kwh, but need help!

Cariboocoot wrote: »

....
To get loads down start by investigating that water pump. It probably doesn't run long per day, but a 240 VAC pump could be a big power consumer with a large start-up demand. It may be possible to change out for a smaller unit that doesn't consume so much, depending on what your well is.....

You will need a chart of "water pump curves" to nail this.

Figure what your demand is (2 garden hoses, and the washing machine) and find a pump that works at that depth and volume.
Get the right size pressure tank, generally, larger = better, 50- 80 gallon size gives you 25-40 gal storage (the rest is air bladder) Larger tank = fewer pump starts.
Pump starting is a power hog. Frequent starts with a small tank = more hog

A 1.5hp pump @ 3 gpm is a power hog 1/2hp is a better match (but not what the wel driller carries on his truck).

A 240V pump is more efficient than a 120V pump (less losses in the wires, and easier to start - even if you have to invest in a step up transformer from a 120V inverter)

snuffy · August 2011

Re: Down to 250kwh, but need help!

You might want to take a look at the Sun Danzer freezers. Pricy but super efficient. Have a friend in Minnesota that has a couple of them and he's off grid. Loves em. They run off DC or AC.

SCharles · August 2011

Re: Down to 250kwh, but need help!

That water pump...our well is deep, but the water level is such [flowing well], that our pump only "sees" a hundred foot or so head. Not so far off yours. Plus, ours is set at about 8500 Mean Sea Level so the pump performance would be derated. Although it is rated at 5 gpm and that is about what I have measured, go figure.

Anyhow, ours is a Grunfos soft start, 110 volt model. We run it off a normal inverter. From our 12 v. battery bank but only during sunshine hours. I don't recall the electrical usage, could figure it out if you need, but it is far lower than your 220 v. pump without my even checking.

The freezer...if you are willing to recycle it and lay out money for a more efficient one, you would be much money ahead in your purchasing an off-grid system, should you decide to go ahead with it. Lots of money. It is far costlier to beef up a PV/battery/etc. set-up than to get rigged up with more efficient elec. users in the first place. We have a supremely efficient [low DC power] Sunfrost freezer, but it is only 10 cu. ft. and not many elk or moose would fit into it. Like, not even one. I believe they make an 18 cu. ft. model, but I don't recall. These units are, however, pricey. I believe our 10 cu. ft. was a bit over $1600 plus trucking.

Same with the PCs. We run several Mac's, and I've gone to all laptop stuff. My wife runs both a Mac and Dell PC, both laptops. She was running Linux on the Mac til a couple years ago, no problems. All our laptops [we usually don't run more than three simultaneously, just because that's what we need] don't use the power our old desktop unit used to draw.

In short, best bet is to keep dreaming and calculating and planning and learning. Meanwhile, as you need to replace stuff [computer stuff, appliances, etc.], choose the lowest energy users you can stand. In many cases, the really efficient models are not much, if any, more costly than others. By doing that, you can save thousands in the size of your PV array and battery bank or whatever type of system you choose.

Amazon.com has Kill-A-Watt meters for around $25, just bought one myself about six months ago. Get one if you don't have one, you can plug in stuff, like that suspect 'fridge, and see how much it is using. Leave it plugged into it for 24 hr. and see what the daily draw is. I found that our flat-screen TV used a lot less than what the owner's manual indicated, for example. Cool.

techntrek · September 2011

Re: Down to 250kwh, but need help!

Often you can get flat-screen TVs even lower by turning down the backlight a few notches.

chevenstein · September 2011

Re: Down to 250kwh, but need help!

Aside from being able to actually start and run the pump, unless you're pumping water all day the well pump isn't much of a factor off grid in my experience. I'm off grid with the system in my signature and have an enormous well pump (I think it's 1.5 or 2hp) and do not have any issues supplying it with power. My pump runs for maybe a total of maybe five to ten minutes in a given day, depending on whether or not we run the dishwasher or do laundry, so even if it's using a couple of kW running (which it does), it's only a fraction of a kW hour. Note that the large current draw takes the state of charge in the batteries down more than a slow, longer draw of the same kWh, but it's still not enough to matter.

That said, the batteries need to be able to sustain the massive startup load through the inverter and keep the voltage up while it's running. In my case I had trouble with my 220Ah training battery bank, but have not been having trouble since doubling that to the 440Ah bank.

Finally, I've done a fair amount of work on investment properties and the homes of friends and family and with two exceptions, have never seen a deep well pump larger than 3/4hp. Most are 1/2hp in wells between 100 and 150 feet deep. I have seen a couple of 1hp jet pumps, but those were for shallow wells (~30 feet) with really long horizontal runs to the house. The exceptions are my 400 foot well and a friend's mansion with 3hp pumps in two 600 foot wells.

waynefromnscanada · September 2011

Re: Down to 250kwh, but need help!

chevenstein wrote: »

Aside from being able to actually start and run the pump, unless you're pumping water all day the well pump isn't much of a factor off grid in my experience. I'm off grid with the system in my signature and have an enormous well pump (I think it's 1.5 or 2hp) and do not have any issues supplying it with power. My pump runs for maybe a total of maybe five to ten minutes in a given day, depending on whether or not we run the dishwasher or do laundry, so even if it's using a couple of kW running (which it does), it's only a fraction of a kW hour. Note that the large current draw takes the state of charge in the batteries down more than a slow, longer draw of the same kWh, but it's still not enough to matter.

That said, the batteries need to be able to sustain the massive startup load through the inverter and keep the voltage up while it's running.

That basically has been my experience with the 1/2 HP submersible pump I used to run off solar when I had the camp. And it was a standard, off the shelf 110 volt Franklin motor with the external starter box, easier to start than those with built in starter. and back then I only had 500 watts PV. Like you say, unless you're using one heck of a lot of water, it just doesn't run very much and runs for shorter times than a lower consumption, slower pump. The biggest water saver was going with a front load washer, a huge difference. Right now I'm using the 1/4 hp, dual cylinder piston pump shown in my avatar, but one of these days I'm going to hook up the 1/2 HP 220 volt submersible that's already in the same well, but hasn't been used for a few years because all I had to power it was a 1500 watt MSW through a transformer. I now have a far, far better pure sine inverter. Only thing is, the 1800 watt PS inverter probably won't be able to run the pump and make toast at the same time, which is no problem with the piston pump

Steven Lake · September 2011

Re: Down to 250kwh, but need help!

Wow, from what you guys are pointing to, it looks like my order for tackling things should currently be:

Well Pump
Fridge/Freezer
Computer/PC.

I'll work on those and see how far I get on reducing things. I'd like to get my system setup for $10k or less if possible. Assuming a 48v rig, what should my preferred average KWH usage target be? 200kwh? 150? 100? Whatever it is, I'll try to get it down to that level.

BB. · September 2011

Re: Down to 250kwh, but need help!

Make sure you look at Watts*Hours (or Amps*Hours) for your power usage... Yes a big well pump will set the top end of the system size (inverter, battery bank AH/Voltage ratings)...

But how many hours you run that will size the solar array (and to a degree, the battery bank too)...

A 1,500 watt microwave running a 1/2 hour a day vs a 200 watt desktop+networking+laser printer running 12 hours a day:

1,500 Watts * 1/2 hours = 750 Watt*Hours per day
200 Watts * 12 hours = 2,400 Watt*Hours per day

So--the micro wave sounds like a large load (and it is a large peak loads), but your solar array will have to be 3x larger to manage the "low power" computer running 1/2 the day.

In the end, know your loads (plus rough distances from Array to Battery Shed/Loads) and then we can help size the system and suggest some components for you to review and see how they meet your needs.

Trying to start in the middle without knowing your loads--can be very confusing.

-Bill

Cariboocoot · September 2011

Re: Down to 250kwh, but need help!

Bill's absolutely right. Take it from a guy who runs all this stuff of grid: me.

Water pump: 1/3 HP. Draws a nasty 850 Watts when running, but runs for 6 minutes a day: 85 Watt hours

Digester (septic) pump: 1 HP. 1200 Watts when running, but runs for less than 1 minute a day: 20 Watt hours.

These two monsters are kept under control by being allowed to come on only when the batteries are recharged.

Microwave: 1050 Watts (700 Watts cooking - the smallest actual power user I could find at the time). Runs for ??? A minute or two. I've never used it longer (it's unplugged most of the time). 35 Watt hours, perhaps.

Refrigerator: 1200 Watt hours per day (it's a good one even though it's not E-Star rated).

Old desktop computer: averaged 160 Watts w/ 19" monitor. 8 hours a day it would be on: 1280 Watt hours.

So the smallest can be the largest and vice versa, but the big Watt users do dictate inverter size and to some extent battery bank size.

The laptop at 35 Watts maximum has been a huge improvement. Much cheaper to buy one of those than to pay for the extra capacity to power the desktop.

Steven Lake · September 2011

Re: Down to 250kwh, but need help!

BB. wrote: »

Trying to start in the middle without knowing your loads--can be very confusing.

Thanks for the advice. I wasn't trying to start in the middle so much as I was trying to get my loads down to a viable level before moving on to building the system. I figured that if I had my loads within the target range, it'd be easier to build the system, as you guys said I should size my loads to the system, and not the system to the loads. Thus what I'm trying to do.

BB. · September 2011

Re: Down to 250kwh, but need help!

I understand what you are doing and agree with trying to get loads down to a minimum before you go too far down the solar road.

In the olden days--about 100kWH per month (3.3 kWH per day) was a good aim point for solar... Even today, that is a pretty reasonably priced system.

Yes, you can do more, and many people do--But it gets surprisingly expensive and complex to do larger systems.

To give you an idea--Use somewhere around $1-$2+ per kWH for your off grid power... To "save" 150 kWH per month (100 vs 250 kWH per month usage) will shave around $150-$300 PER MONTH off of your "imaginary" power bill.

When you take equipment life and battery replacement into account (and losses, etc.)--Solar power never seems to go below that $1-$2+ per kWH price (if this is a summer/weekend place, the power prices can even be higher).

-Bill

Cariboocoot · September 2011

Re: Down to 250kwh, but need help!

Bill;

It looks like we have to revise that $1-$2 per kW hour number: http://forum.solar-electric.com/showthread.php?t=12655

There are things that will make it more expensive, like lower efficiency location (hot panels, smog) but over-all the price on panels has come down significantly - to the point where a good location (more than 4 hours equivalent sun) with an efficient install could bring that number close to what GT solar traditionally cost. Although the price on that has been dropping for the same reason.

Still no place near our utility's $0.10 per kW hour though. :cool:

BB. · September 2011

Re: Down to 250kwh, but need help!

Yes, for diy installs, and people that find great deals can do it for less than $1 power hour... But I am a bit of a pessimist and try to set expectations for planning.

In the end, it is pretty ready to take the entire cost over ten to twenty years divided by kWH over ten/twenty years and see what your costs may be.

-Bill

RobertMfromLI · September 2011

Re: Down to 250kwh, but need help!

Cariboocoot wrote: »

Watts isn't unusual for one, but a laptop with a 17" screen will use 150 Watts less.

Sadly, other than netbooks, which may not be very suited for programming (and the requisite "compile"/"test" steps), a suitable laptop will generally draw 65W, 90W or 130W (or much more for the bigger ones with 17" screen and gaming capable hardware, such as the XPS series and Alienware series - which draw 230W). You can expect a slightly bigger draw than their rated outputs.

The laptops will also draw more if the battery needs charging (not maintenance... but "I ran down the batteries a bit, need to charge them).

Best,
Rob

Cariboocoot · September 2011

Re: Down to 250kwh, but need help!

Rob;

I don't know what you're running for a laptop, but several of us here have actually tested ours. 65 Watts? None that high, much less higher. If you've got one sucking down 230 Watts, no mater what it's doing, you should seriously look for something better. Off-grid is no place to be using Watts wantonly. :roll:

RobertMfromLI · September 2011

Re: Down to 250kwh, but need help!

Cariboocoot wrote: »

Rob;

I don't know what you're running for a laptop, but several of us here have actually tested ours. 65 Watts? None that high, much less higher. If you've got one sucking down 230 Watts, no mater what it's doing, you should seriously look for something better. Off-grid is no place to be using Watts wantonly. :roll:

Gaming systems suck that much - they are really high end gaming computers shoved into a 20 pound laptop case. As for power consumption on regular laptops, compiling code and running certain applications will suck near it's rated output - which *is* 65/90/130 depending on the machine, for virtually every standard laptop there is. Surfing the web, checking mail, other intermittent use, and the things will drop to the 20-40W range. As a programmer, I know my machine is rarely in the "I can go into low power mode" usage. His usage patterns may vary.

(edited below)
Here's the problems... the virtually always on CCFL backlit LCD draws 20-25 watts (no sleep, no dim (not the best on the eyes when programming)) about 12-18W on an LED backlit LCD. The CPU is rarely "idled" or slowed for power consumption. Those generally will draw 30-65W at full tilt. Sadly, a world of difference than a "normally used" laptop that dims screen or sits at low CPU usage most of the day. Though, I must admit, much of what I do eats CPU (often keeping it pegged at 100%), but a lot of that is video stuff.

Though, in the grand scheme of things, I do see the difference and where your math may indeed be correct - one can cut the LCD's current draw out of the equation since there's the external LCD which was being used with the desktop (which isn't part of the equation, I'm presuming). Duh! Shoulda thought of that.

Vic · September 2011

Re: Down to 250kwh, but need help!

I must be missing something. And not to be argumentative,
BUT, I cannot see how a laptop could get rid of even 100 watts to ambient temps, without being close to red hot.

Do not use a LT, and have not meausred the power in on one, but, it would seem to me that at the powers noted, one could not have one near one's lap.

JMHO, Vic

RobertMfromLI · September 2011

Re: Down to 250kwh, but need help!

Vic wrote: »

I must be missing something. And not to be argumentative,
BUT, I cannot see how a laptop could get rid of even 100 watts to ambient temps, without being close to red hot.

Do not use a LT, and have not meausred the power in on one, but, it would seem to me that at the powers noted, one could not have one near one's lap.

JMHO, Vic

Pretty simple:

Take a high end gaming desktop with dual high end video cards
Add a high end multicore CPU
Drop on a large LCD (think 19") - maybe a 20" instead.
Add at least two hard drives
Cram that into a "laptop" case
Call it an Origins PC Gaming Latop or Alienware mALX or one of numerous others out there
Keep the power brick (which alone weighs as much as a normal laptop) away from anything flammable :roll:
Do NOT put on lap - it gets more than hot enough to be uncomfortable 8)

mike95490 · September 2011

Re: Down to 250kwh, but need help!

RobertMfromLI wrote: »

[*]Do NOT put on lap - it gets more than hot enough to be uncomfortable 8)
[/LIST]

Supposedly, the high power ones cause this
Laptops may damage male fertility
http://news.bbc.co.uk/2/hi/4078895.stm

chevenstein · September 2011

Re: Down to 250kwh, but need help!

And don't forget about the other monitor. I too am a professional programmer and need two BIG displays to work effectively. At home I compromise with a large LCD display plus the barely adequate display built into the laptop (1440x900); at work it's two even bigger wide aspect displays and I'd add another one if it would fit on the desk. I have a colleague who runs TWO 30" 2560x1600 displays...four IDEs side by side might actually be too much real estate, but you get the idea.

When I work from home I probably double the house's daily consumption, excepting long sunny days when we run laundry for six hours straight. I'm down to about 50 kWh per month, give or take, and that's still a little high in the winter for my area (upstate NY).

RobertMfromLI · September 2011

Re: Down to 250kwh, but need help!

mike90045 wrote: »

Supposedly, the high power ones cause this
Laptops may damage male fertility
http://news.bbc.co.uk/2/hi/4078895.stm

LoL, I don't doubt it... fortunately, I only repair them... or unfortunately, as the case may be (as in, I don't own one).

Down to 250kwh, but need help!

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