power supply questions

emotion_sickness · Post by **emotion_sickness** » Mon Jan 14, 2008 4:26 pm

Im looking for some form of power supply to run a laptop, amp & speakers, and maybe a few colored floodlights (basically a very minimalist DJ-ing setup) so i can put on dance parties in remote areas (I will be working at Glacier Natl Park this summer) It doesn't necessarily need to be tough enough to survive the playa, (although that would be nice too) but I need it to be quiet as i dont want a noisy generator drowning out my music, be able to run my equipment for a good 6-10 hours, easily portable, and be rechargable off of just a regular power outlet. I also don't want something that will power surge and fry my laptop or blow out my speakers. Solar power is probably ruled out, considering it will usually be used at night.

any ideas or recommendations?

Dork · Post by **Dork** » Mon Jan 14, 2008 4:32 pm

With batteries, you'll be limited in what you can power and when you run out of power that's it. If you can come up with some numbers for the power requirements of the equipment you have now we can crunch some numbers, but I suspect you won't like the answer.

I'd spring for a Honda EU1000i or EU2000i generator. They're light, very reliable, very quiet, and the power is very clean.

Kinetik V · Post by **Kinetik V** » Mon Jan 14, 2008 5:09 pm

Considering the hassles of lugging around batteries, even the gel mat spiral core ones, then messing with a inverter that puts out dirty power that your electronics won't like, I agree with Dork. I'd spring for the Honda generator and in particular the EU2000i. If your batteries go down you're stuck looking for an outlet to charge up with and you've just killed your party. With the Honda and just one 5 gallon gas can you've got plenty of power to run all night long.

And if you're having these parties on the sly sans permit and don't want to get caught, the Honda is so quiet that it won't draw attention say if you had to cut the music and couldn't get over to shut the genny off right away.

One other thing about the Honda...the power is clean enough to run a laser printer which is very finicky on having clean power to run. Your electronics will love it vs. using the inverter.

emotion_sickness · Post by **emotion_sickness** » Mon Jan 14, 2008 5:32 pm

Yamaha's EF1000 looks to be quite a bit cheaper and along the same lines as the honda one...

that looks like one of the big problems is being able to afford the $1000+ for a generator...originally i was thinking of just getting an inverter and running it off my car battery, but that would limit me to playing in places where i can drive to and park my car at (aka the side of the road lol) but it would be a lot cheaper.

here's the specs for my speakers from the manf. website...they are just little desktop satellite speakers and a sub but they get pretty loud especially when out in the boonies and its just the crickets... not sure what everything here means as i dont know a lot about electronics, im more of a plug and play type!

Speaker System
Input Impedance >5K
Signal-to-Noise Ratio >80dB
Frequency Response 50 - 20kHz
Input Sensitivity 400 mv rms for rated power output
Voltage Input 120 VAC

Satellite
Drivers One Odyssey Plus transducer
Power Rating 8 watts per satellite at 10% (THD+N)
Dimensions (H x W x D) 3" x 3" x 3"

Subwoofer
Drivers One 4.00 inch Magnum transducer
Power Rating 24 watts at 10% (THD+N)
Crossover Frequency 180Hz

not sure about the laptop as i havent decided which one i want to get yet, but that can run off its own battery for a few hours at least before it would need to get plugged in. here are the power specs for a dell i am looking at, i would assume they would be pretty similar to other laptops on the market:

4-cell 28WHr Li-Ion Battery
6-cell 56WHr Li-Ion Battery
9-cell 85WHr Li-Ion Battery

as for the lights, it would probably be just a string of xmas lights or a couple 60 watt colored party lights.

would i be right to assume that i just add up how many watts each device will be using and multiply by the # of hours to get the total # of watts i need to generate? that seems too simple to me

phil · Post by **phil** » Mon Jan 14, 2008 5:50 pm

This is a fairly common question, and I did a quick search of the Q&A board for
inverter battery
and got a lot of threads turn up. I'd suggest browsing there.

I've camped near the Honda EUxxxx generators, and they are _not_ quiet. They _may_ be quieter than other brands, but they are not quiet.

Inverters put out square wave, modified sine wave, and sine wave 110V AC. You need to know if your equipment requires true sine wave or will run on square or modified wave.

To find out if you can run X number of hours off a battery, you need to know the wattage draw of each piece of equipment. Add that up to total watts.

Watts = volts X amps

Batteries have 12V, so if you have a 100 amp-hour battery, you've got
Watts = 12V X 100 amp-hours = 1200 Watt-hours.

If your gear totals to 1200 watts, you can run it an hour on a 100 amp-hour battery. If the gear totals 200 watts, that's 6 hours. A hundred amp-hour battery is honking huge. I have a 110 amp-hour battery that weighs 70 pounds.

The inverter sucks some juice out of that, too, so don't forget to add it into the total wattage.

If you can recharge your battery off the mains, you'll need a charger for the battery.

So you'll need the proper inverter for your gear, a charger, and a battery with the number of amp-hours that formula gives you.

Now let me ask the question: if you can recharge off a regular power outlet, how come you don't run your gear off that outlet?

Captain Goddammit · Post by **Captain Goddammit** » Mon Jan 14, 2008 6:08 pm

Total number of watts x hours of use = watt-hours. Batteries are generally rated in amp-hours. Watts is volts x amps. A 12-volt battery that makes 1 amp-hour (ah) therefore produces 12x1=12 watt-hours. A 12-volt battery that makes 10 ah gives you 120 watt-hours.
You have to figure in a fair amount of losses. Inverters are not 100% efficient, cables and connections have losses, etc.

If you'll be near your vehicle, you could add a second battery... a deep-cycle battery. You'll likely end up draining your car's starting battery if you use it to power your party. Deep cycle batteries are what RVs and boats use for their "house" power. They're designed to put out gradual amounts of power over a long time, as opposed to car starting batteries, which are designed to provide huge bursts of power for very short periods of time.

You'll need a battery isolator to allow your car's alternator to charge the extra battery and allow use of it without draining the starting battery.

To make it all work well, you'll spend a few hundred bucks...

But I agree with what's already been said before. The small, lightweight, portable, super quiet generators just can't be beat.

The Honda EU 1000 and EU2000s are terrific, I have a few of each myself. The super-quiet model Yamahas are excellent also.

If you can't afford one then check Craigslist for a deal on a used one. I bought an EU1000 once for $400.

I also heavily recommend the 2000 watt set over the 1000.

Captain Goddammit · Post by **Captain Goddammit** » Mon Jan 14, 2008 6:10 pm

OK, Phil, you type faster than I do...

emotion_sickness · Post by **emotion_sickness** » Mon Jan 14, 2008 6:29 pm

phil wrote:Now let me ask the question: if you can recharge off a regular power outlet, how come you don't run your gear off that outlet?

...because the outlet will be in my room, miles and miles away...im looking for something i can load into the car, drive to a trailhead, and hike a few hundred yards into a clearing or campsite and set up in the woods. more in the boonies than the playa...complete with tons of bears!

sounds like the generator is going to be the way to go...

i guess ill just have to save $$ and check craigslist and ebay until i head up there in may. thanks for all the help!

Gizmo · Post by **Gizmo** » Mon Jan 14, 2008 6:49 pm

I agree with everyone who suggested the Honda EU2000i. I bought one last year at a national chain tool store, on sale and 12 months no
interest. Cost me about 70 bucks a month. It has a throttle which
conserves gas when you have less stuff plugged in. Runs my vintage
Pioneer receiver (1970's) all night for just over a gallon of gas.

MikeVDS · Post by **MikeVDS** » Mon Feb 18, 2008 7:10 am

Yeah the EU 2000s are great.

As for the inverter, they do make them so that you have pretty damn close to a real sin wave. They are just much more expensive. Also the alternator in your car may not be able to keep up with your equipment. You'll also have to keep your car running...

burnerboy33 · Post by **burnerboy33** » Mon Feb 18, 2008 8:29 am

you people do know the honda and yamaha supper quiet generators are inverters right? They produce 12v then run that into an inverter.
I have a 1000w pure sine inverter in my truck and it puts out the cleanest 120v I'v seen on any other inverter or EU series gererators.

phil · Post by **phil** » Mon Feb 18, 2008 9:58 am

burnerboy33 wrote:I have a 1000w pure sine inverter in my truck

What did it cost?

burnerboy33 · Post by **burnerboy33** » Mon Feb 18, 2008 10:57 am

I don't know what it cost. It came with the truck.

Captain Goddammit · Post by **Captain Goddammit** » Mon Feb 18, 2008 7:56 pm

burnerboy33 wrote:you people do know the honda and yamaha supper quiet generators are inverters right? They produce 12v then run that into an inverter.

It's not that simple... they actually produce very high frequency AC, then rectify it into DC and then into an inverter that produces stable 60Hz sine wave AC.