Please help with Electricity Math

VoKuS · Oct 10, 2011

I have a computer gaming rig, that draws around 600 - 700 watts at the 120v wall socket when its under full gaming load.

I would like to be able to run this computer in my car for at least 5 hours straight.

If I combine a whole bunch of 3s Lipo packs in parallel for capacity, and then run it thru a good inverter how much capacity at 3s would need to run my computer for 5 hours.

Erogo · Oct 10, 2011

700 watts for five hours? You need 3500 watt hours of capacity.

If you get your lipo seriesed up to deliver 120V, then your 700 watts will be drawing about 5.8 amps. So you need to deliver 5.8 amps for five hours? 29 amp hours. Most packs are speced in milliamp hours, so you need to get 29000 milliamphours of 120v-seriesed packs.

If you get your lipo seriesed up to deliver 12V (3s packs), 700 watts will need 58 amps. You need to deliver that for five hours, so 290 amp hours. 290 000 maH of 3s packs.

Get a cheaper hobby bro!

Eric

Hillhater · Oct 10, 2011

Or you could just get a high capacity alternator fitted to the car, and run the motor for 5 hrs ! :shock:

Cheaper & simpler to buy a small 120v generator and run from that.
EDIT:..
you know, that 700W is a peak demand, and the average is probably less than half that. so your standard car battery with the alternator running would most likely be able to feed the converter if you hooked direct to the battery. :wink:

VoKuS · Oct 10, 2011

Erogo said:
700 watts for five hours? You need 3500 watt hours of capacity.

If you get your lipo seriesed up to deliver 120V, then your 700 watts will be drawing about 5.8 amps. So you need to deliver 5.8 amps for five hours? 29 amp hours. Most packs are speced in milliamp hours, so you need to get 29000 milliamphours of 120v-seriesed packs.

If you get your lipo seriesed up to deliver 12V (3s packs), 700 watts will need 58 amps. You need to deliver that for five hours, so 290 amp hours. 290 000 maH of 3s packs.

Get a cheaper hobby bro!

Eric

(ZIPPY Flightmax 8000mAh 3S1P 30C $41.73) X (36.25) = $ 1512.71 + Charger + Inverter Inefficiency....

How about 2 X 1000 watt portable honda generators ?

Erogo · Oct 10, 2011

Hmm, that doesnt sound too bad actually does it vokus! And as Hillhater pointed out, your 700w is probably max, so you'd get more than your five hours out of it. Or you could run somethign else off it at the same time, like a decent sound system. You'd have to power a screen of some sort as well eh?

E

AussieJester · Oct 10, 2011

And still nobodies questioned putting baby rapping house burning lipos in a car :shock:

i'm impresed ES, things are looking up :mrgreen:

KiM

Erogo · Oct 10, 2011

I'd strongly recommend heatsinking the lipos against the petrol tank. The mass of fluid within should keep the lipo at an optimum working temperature, ensuring you get maximum life from them.

Probably using the metal of the petrol tank as a common earth is a good idea as well, you can use your battery tab welder to spot weld anything to the petrol tank. Just remove the filler cap first, to ensure any vapours produced have the chance to escape so they don't build up too much pressure.

Note this does not constitute financial advice. Your mileage may vary. Think before you act.

E

stingray17 · Oct 10, 2011

For running a mobile computer, you would be better off if you can reduce your power needs at least a little bit! Might mean running only one hard drive, one video card instead of SLI team, etc.

Then skip the inverter and AC power supply, and run the PC from an M4-ATX. It's a DC-DC computer power supply that will deliver 250W (300W peak) to power your computer from any 6-30 VDC power supply. It has some other useful features for a mobile car system also (amplifier remote turnon, auto shutdown on a timer connected to ignition, etc).

You could then either connect the PC directly to the car battery, or you could run 6s lipo instead of 3s. Either way, no inverter. You could find a monitor that works on 12 or 24 VDC (many LCDs with external brick supplies use one of these voltages) and plug it straight into the car battery or the lipo battery pack - but probably better to also run that through a DC-DC converter/regulator.

Of course as others have said, just hooking a 1500W+ inverter up to the car battery directly and leaving the car motor running would be a much cheaper option... If you really draw 700W all the time you would need to upgrade the alternator but if your average loads are much less than that (and they probably are) then a stock alternator would probably get the job done.

slayer · Oct 10, 2011

VoKuS said:
Erogo said:

700 watts for five hours? You need 3500 watt hours of capacity.

If you get your lipo seriesed up to deliver 120V, then your 700 watts will be drawing about 5.8 amps. So you need to deliver 5.8 amps for five hours? 29 amp hours. Most packs are speced in milliamp hours, so you need to get 29000 milliamphours of 120v-seriesed packs.

If you get your lipo seriesed up to deliver 12V (3s packs), 700 watts will need 58 amps. You need to deliver that for five hours, so 290 amp hours. 290 000 maH of 3s packs.

Get a cheaper hobby bro!

Eric

Click to expand...

(ZIPPY Flightmax 8000mAh 3S1P 30C $41.73) X (36.25) = $ 1512.71 + Charger + Inverter Inefficiency....

How about 2 X 1000 watt portable honda generators ?

since it is 700 watts hours you spend then you would need a single 1000 watts honda genereator ...in that case you don t need to take in account the total watt hours but you have to find out how much gas is needed to power for 5 hours

Kingfish · Oct 10, 2011

I don’t understand the problem. Standard HD-alternators run 90-120A. At 12V, that’s more than enough juice to run the car and the computer. It is vastly cheaper to upgrade the existing or string another alternator on than to go out and buy a bunch of lipo. 12V 1kW pure-sine wave inverters are less than $200. I had one in my truck for camping; we used it to run the coffee grinder (faster than a Turkish hand-crank; when it's freezin' cold - you don't want to take 1/2 hour to grind coffee :lol: )

~KF

liveforphysics · Oct 10, 2011

stingray17 said:
For running a mobile computer, you would be better off if you can reduce your power needs at least a little bit! Might mean running only one hard drive, one video card instead of SLI team, etc.

Then skip the inverter and AC power supply, and run the PC from an M4-ATX. It's a DC-DC computer power supply that will deliver 250W (300W peak) to power your computer from any 6-30 VDC power supply. It has some other useful features for a mobile car system also (amplifier remote turnon, auto shutdown on a timer connected to ignition, etc).

You could then either connect the PC directly to the car battery, or you could run 6s lipo instead of 3s. Either way, no inverter. You could find a monitor that works on 12 or 24 VDC (many LCDs with external brick supplies use one of these voltages) and plug it straight into the car battery or the lipo battery pack - but probably better to also run that through a DC-DC converter/regulator.

Of course as others have said, just hooking a 1500W+ inverter up to the car battery directly and leaving the car motor running would be a much cheaper option... If you really draw 700W all the time you would need to upgrade the alternator but if your average loads are much less than that (and they probably are) then a stock alternator would probably get the job done.

This is all great advise. Seems like you've got some big power wasters in your gaming rig, most modern CPU's eat a surprisingly low amount of power, and modern graphics cards with tiny transistors are also not too bad on power for the great performance. Unless your rig is like a triple SLI setup or something, it just seems like a lot more power than you need.

DC/DC power supply as mentioned above is the way to go. I think going with something like Thunder-sag's would be well suited to this application where weight and size aren't key priorities. I would throw 4 of this cell in series, balance them, and connect it right up to the cars factory charging system, connect your DC/DC computer power supply, and be done for ~$1000 bucks.

http://currentevtech.com/Lithium-Batteries/Thundersky/Thundersky-200ah-cell-p27.html

amberwolf · Oct 10, 2011

FWIW, it's pretty likely the regular computer PSU will run off DC, at 120V or higher. If you bypass the bridge rectifier, going straight to the input caps, it'll be better, but even straight to the AC input will likely work fine (but may eventually overload the bridge diodes if running at peak power output long enough).

So as suggested previously, you could use 120V(min) of battery of your choice, no inverter, and save the inverter inefficiencies. Theory easily tested with an old PSU or computer system.

DC-powered PC PSUs work, too (I have a couple small 48V-powered units somewhere), but if you're not going to use this rig but once, why spend the money on one when buying the batteries you'd still be able to use on your ebike or lots of other things.

But if you are going to do this a lot, the DC-powered PSU is probably better.

ZOMGVTEK · Oct 10, 2011

High end gaming rigs are a marvel of inefficiency. First rule of over clocking is to make sure you turn every feature off that sounds like it might save power, or want to down clock the processor on reduced demand. If me and my brother leave our computers on in the same room, it ends up burning hot in no time, or the breaker trips. True story.

Don't bother with running the thing off electrochemical storage. This is why gaming notebooks don't run for more than 20 minutes, the battery would be HUGE and cost a small fortune. You need a generator, or idle the car and run it off an inverter. Don't run it very long without starting the car, and it wouldn't be a bad idea to charge your battery on a quality charger after abusing it with this kind of ordeal.

VoKuS · Oct 11, 2011

Ok here is what I am trying to run in my car.

System Specs
GPU: Asus GTX590
CPU: Sandy i5 2500K
RAM: G.SKILL Sniper Low Voltage 8GB
MOBO: ASUS Maximus IV Gene-Z
PSU: Antec High Current Pro 1200W
SSD: Intel 80GB
HDD: WD 1TB
WALL MOUNT: MYOPENPC BENCH Wide Wall

Accessories:
LCD: Asus VG236H 23" 2ms 1920x1080 120Hz 3D
Glasses: nVidia 3d Vision Kit
Keyboard: Rosewill RK-800G Black Gaming Keyboard
Mouse: Razer Orochi
Cans: Psyko Carbon 5.1

Its going in to this car, im removing the passanger seat.
Plus I have alot of other electronics I will run, I dont think I will have a big enough alternator... So battery res is the way to go...

amberwolf · Oct 11, 2011

Well, at least teh LiPo you can then reuse on your bike(s).

FWIW, I think that fuzzball could use a booster charge, too.

theRealFury · Oct 11, 2011

Hey,

My gaming rig is similar to yours apart from i use an older, less efficient quad core CPU and i have the older SLI GTX295 cards. Also i dont have the 3D glasses but i do have a 26inch IYAMA 1080p monitor. My peak power drain while gaming is ~490watts and my idle power drain is ~200-250w depending on what is running in background. I measured this as i was thinking of running my PC from solar but decided against it at the time. Surely the 3D glasses can't use over 200w of power. Are you sure you made the measurements correctly? I use a coolermaster 1000w PSU but it hardly even gets a workout.

On a slightly off topic note... how is the Nvidia 3D gaming kit? Is it comparable to the best 3D TV's out there or is it just giving a little perspective?

VoKuS · Oct 11, 2011

theRealFury said:
Surely the 3D glasses can't use over 200w of power.

Surely I dont understand the above ^^^

theRealFury said:
Are you sure you made the measurements correctly?

Not really

Best I can do is give more info.
GTX 590 ( DUAL GPU ) Running Maxed Settings and 3D mode 1920 1080 ( 3D Mode Def Pulls More Watts )
CPU at 4Ghz ( Stock Cooler )
Monitor Pulls 60 Watt
5.1 Headphone amp prob contributes a little too...
Seems reasonable to me...

theRealFury said:
how is the Nvidia 3D gaming kit? Is it comparable to the best 3D TV's out there or is it just giving a little perspective?

True 120 Hz Monitor and Active Shutter Glasses is the best you can get right now... As far as I know its better then any 3D or simi 3D TV out their...

If your system can pull it, you are getting 60 fps per eye, full depth perception. Looks super real...

Not all games are supported, and not all people work well with 3D, some people get headaches...

Im fine, I love it, 3D and 5.1 scares the shit out of me sometimes..

If your super rich, you can get a $10,000 dollar Sony Projector that does 240 FPS and have 120 FPS per eye, but then you system has to be able to unload that type of frame rate... expensive...

theRealFury · Oct 11, 2011

VoKuS said:
theRealFury said:

Surely the 3D glasses can't use over 200w of power.

Click to expand...

Surely I dont understand the above ^^^

Sorry, i was just saying that i was hopeing that the 3D glasses did not pull 200 watts of power

VoKuS said:
theRealFury said:

Are you sure you made the measurements correctly?

Click to expand...

Not really

Best I can do is give more info.
GTX 590 ( DUAL GPU ) Running Maxed Settings and 3D mode 1920 1080 ( 3D Mode Def Pulls More Watts )
CPU at 4Ghz ( Stock Cooler )
Monitor Pulls 60 Watt
5.1 Headphone amp prob contributes a little too...
Seems reasonable to me...

ok Perhaps the GTX590 pulls alot more current then my GTX295's, i would have hoped that newer stuff would have been more efficient but perhapse not

I measured mine by plugging everything into a 8 socket extension and then attatching an AC clamp meter to the cable to measure the amps. on full load i saw 2.0amps flickering to 2.1amps on our 240v supply.

VoKuS said:
theRealFury said:

how is the Nvidia 3D gaming kit? Is it comparable to the best 3D TV's out there or is it just giving a little perspective?

Click to expand...

True 120 Hz Monitor and Active Shutter Glasses is the best you can get right now... As far as I know its better then any 3D or simi 3D TV out their...

If your system can pull it, you are getting 60 fps per eye, full depth perception. Looks super real...

Not all games are supported, and not all people work well with 3D, some people get headaches...

Im fine, I love it, 3D and 5.1 scares the shit out of me sometimes..

If your super rich, you can get a $10,000 dollar Sony Projector that does 240 FPS and have 120 FPS per eye, but then you system has to be able to unload that type of frame rate... expensive...

Well my gaming rig is 2 years old now and the new games coming out are starting to drop below the 30FPS at times so when i get round to upgrading then ill be considdering 3D capabilities this time i think. Thanks for sharing your experience.

ZOMGVTEK · Oct 11, 2011

Your power consumption numbers are way off for that rig.

I'd say 220W idle, with the monitor and whatnot, 360W average load, 400W peak.
This makes it a lot easier to run. Inverter + lead gets the job done.

dogman dan · Oct 11, 2011

Not sure I completely understand the needs. Run for 5 hours in the car. Is the car running, like one guy drives while the other games? Or do you need to sit somewhere for 5 hours and want to game during the wait?

Seems to me if the car is driving, 700w is quite possible with the big alternator, and a second lead acid battery in the car. 700w is nothing in the car stereo or car that hops up and down world right?

FWIW 700w for one hour would be the equivilant of the typical 48v 15 ah pingbattery. So a pretty big pile of lipo would be needed to sit and play for 5 hours. 40 5s 5000mha packs. A 1000w honda generator would cost a fraction of that.

liveforphysics · Oct 11, 2011

I can't see that pulling 700w.

Get a kilawatt meter, plug your rig into it, go play, look at average power draw.

zombiess · Oct 11, 2011

I also don't see that pulling 700 watts, except maybe a spike on cold boot. A 1200W power supply... geez. They are getting silly with computer parts now. I wonder how many of them can actually do their ratings or if it's become like the audio world with cheap plastic peak 500W sound systems powered off a 18V 2Amp wall wart.

Put a Sony 20" Trinatron for a monitor and you'll definitely need a 1500W inverter LOL

Powerful PC's do make great room heaters in the winter

dogman dan · Oct 11, 2011

Definitely worth a 30 buck purchase of a killawatt meter, saving yourself buying half that pile of lipo you'd need.

BTW, proper dog, ears down.

ejonesss · Oct 11, 2011

the12volt.com/ohm/page2.asp is a good site for ohm's law calculations

also if your goal of mobile gaming is to use someone else's wifi because you used up your quota or are being throttled or capped by your isp you may be better off getting verizon dsl since they dont cap, quota or even throttle traffic in fact they are fighting the fcc over the net neutrality rules.

you can get the latest mifi from verizon that comes with 5 gig per month and $10 per gig overage fee to fill in the rest of the month until you get a new month.

you can turn off video and voice chat and free up bandwidth.

for mobile gaming it probably be better to get a gaming laptop because there are some electrical losses in using an inverter.

Please help with Electricity Math

100 W

100 W

100 TW

100 W

100 W

1 TW

100 W

1 W

1 kW

100 MW

100 TW

Administrator

100 kW

100 W

Administrator

10 kW

100 W

10 kW

100 kW

1 PW

100 TW

10 MW

1 PW

10 kW

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