quiet juice

torstein · Post by **torstein** » Mon Aug 10, 2009 3:12 pm

Some buddy out here have a sure thing on how to build and set up a battery array?? we have a camp of 50 people running some LED's and minimal sound also 30' dome w/ LED's and a big sound system and i'm looking for a quick and EZ battery system to run while we have the generator off ( much as possible). was thinking of setting up an array of 4 batteries and i'm trying to figgure out how much time power we could get out of 4 of these 80Amp batterys and if it would even work.
http://www.sears.com/shc/s/p_10153_1260 ... 000P?mv=rr

thanks in advance!

Token · Post by **Token** » Mon Aug 10, 2009 5:58 pm

I have a car receiver, speakers, 300w car amp on a car subwoofer and it runns ~ 4 hours on two of those batteries at full volume.

I would call the system really small.

What is this big sound system you speak of?

gyre · Post by **gyre** » Mon Aug 10, 2009 8:58 pm

Amp/hour rating is what you are looking for.
It is actually a graph depending on temperature and discharge rate.
Temperature is a factor usually too.

A 10 amp/hour battery might be 5 amp/hour battery at a high rate.

Example- 100 amp/hour at 20 hours= 1 hour rate of 65 amp/hours.

http://www.ragebattery.com/Merchant2/me ... ode=ps-12v
http://www.ragebattery.com/pdf/ps-4100.pdf

cunfuzelled · Post by **cunfuzelled** » Mon Aug 10, 2009 9:30 pm

an 80 amp hour battery is a batery that will put out either 80 amps of power in one hour or 1 amp in 80 hours or anything with the same ratio.

this would make you think that you have 80 amps of power to use but in actuality you dont. you only have about 60 amps because once the batery falls below around 80 percent depending on the batery your voltage falls to below the specified voltage and is no longer useable.

so if you have 4 80amp hour bateries connected in parallel i would say you would have around a full battery rating of around 320 amp hours which has a usable potential of around 80 percent. that is around 256 amp hours of useable power.

if you look up the rating of your amplifier or your lights or whatever you are going to be connecting to your bateries and it says maximum power 10 amps that means if you used the sterio or lights etc for 1 hour you would be down 10 amps from what you had before that hour. the same is true with charging if your generator charges at a 30 amp rate that means it would take 1 hour to replenish 30 amps of power to your batteries.

with this math you can calculate any power useage you need. if you are using a dc to ac inverter be sure to calculate in the efficiency of your inverter as they all waste some power in the inversion proccess.

Token · Post by **Token** » Mon Aug 10, 2009 11:34 pm

In other words:

You did not provide specific information on your power needs so the answers will be vague.

With your ambiguous question the best advice I can offer is:

Run all the LED lights from the 12V DC battery(s). Charge batteries with an automotive battery charger that runs from the generator 120V AC line whenever the genie is running.

Run your sound systems from the 120V AC generator line. When done with the sound you turn off the generator and still have lights.

Absolut Jeenyus · Post by **Absolut Jeenyus** » Tue Aug 11, 2009 5:15 am

Questions like these can be answered simply by asking the same question to google...

But I ask stupid questions too so... Fuck it...

torstein · Post by **torstein** » Tue Aug 11, 2009 7:55 am

excellent answers!!

does this sound about right ??

4 80amp hour bateries connected in parallel i would say you would have around a full battery rating of around 320 amp hours which has a usable potential of around 80 percent. that is around 256 amp hours of useable power.

20amps = 12hr

2300W = 12hr

gyre · Post by **gyre** » Tue Aug 11, 2009 8:20 am

I'm not sure I follow.

If 256 a/hours is correct for a 12 hour rate, that works out to about 256 watts per hour.
21+ amps X 12 volts = 256 watts/ hour

256 amp/hours divided by hours = amps per hour

Remember temperature is a factor.
And rate of use.

cunfuzelled · Post by **cunfuzelled** » Tue Aug 11, 2009 8:51 am

[quote="torstein"]excellent answers!!

does this sound about right ??

4 80amp hour bateries connected in parallel i would say you would have around a full battery rating of around 320 amp hours which has a usable potential of around 80 percent. that is around 256 amp hours of useable power.

20amps = 12hr

2300W = 12hr[/quote]

if your amplifier is a 12 volt amplifier that draws 20 amps than 12 hours is correct. the rating of 2300 wats on an amplifier is something completely diffrent seeing that audio frequency changes voltage quite quickly in many diffrent directions and the watage changes with the voltage so you never truly have a mean to measure from. the 2300 watt rating is just the maximum wattage your amplifier is capable of putting out. you cannot realy use the rated wattage for calculating battery use. amperage does the same thing on the sound side of the amplifier.

in dc circuitry amps are used to determine power usage because the voltage is always the same where in ac as the sine wave travels up and down the amperage travels in the inverse which makes watage the only stable measurement.

if you are using a 120 volt amplifier that is rated at a max of 2300 watts than you want to find out how many watts the amplifier draws from the wall. this is availible in the user manual or on the net some times. it may also be listed on the back of the amp by the power cord. once you find this out you will want to buy a 12 volt to 120 volt that is rated slightly above the watage your amplifier uses at full. the amps that are drawn from the battery to power the inverter is the number you would use to find your batery life

torstein · Post by **torstein** » Tue Aug 11, 2009 8:55 am

OK so this equasion is correct ??

"If 256 a/hours is correct for a 12 hour rate, that works out to about 256 watts per hour.
21+ amps X 12 volts = 256 watts/ hour

256 amp/hours divided by hours = amps per hour"

if so, i think i got it ;) thanks

what kind of inverter and charger should i get ??

cunfuzelled · Post by **cunfuzelled** » Tue Aug 11, 2009 9:06 am

get an inverter that has around 10 to 20 percent more maximum wattage output than your amplifier. it use to be the fact that you would try to get the one with the highest efficiency but now days they are all pretty much the same on efficiency. so get the cheapest one you can possibly get because the playa may ruin it by the end of the week if you don't keep it out of the dust. so you don't want to be wasting a lot of money on something for only 1 week of use. i have a 400 watt inverter i bought and it draws around 50 amps running on full and i have a 700 which draws a little over 60 amps so that is a good place to go from for calculating before you buy one.

i always use the google product search or ebay to buy inverters as they are cheep on those places. if you have an electronics wholesale house near you they would be a great option also

gyre · Post by **gyre** » Tue Aug 11, 2009 9:08 am

Amperage is used to measure ac as well.
Power used will change with voltage, load, etc.
As volume or music content changes the wattage used changes too.
You may want to measure or calculate a good guess about power needed.

Shop carefully for inverters.
There are forums with much info.
I would want a large safety margin.

http://www.sunelco.com/basics2.aspx
http://www.powerstream.com/Amps-Watts.htm
http://www.northern.edu/wild/LiteDes/ld13.htm

Wiki
Amps multiplied by volts equals watts according to the equation, P = U x I

I is amps and stands for current

U is volts and stands for voltage and

P is watts and stands for Joules per second

cunfuzelled · Post by **cunfuzelled** » Tue Aug 11, 2009 9:23 am

i meant that amps arent the standard rating used in ac for stating the amount of energy used. on the meter the number they measure is watts on your devices the number given is watts you are charged by the killlowatt hour.

where in dc they state on the power supplys that it is 12 volt 7 amps and you dont see to often a 12 volt or dc power suply that is rated in watts. it is just a diffrence in the standard not a diffrence in the science.

Token · Post by **Token** » Tue Aug 11, 2009 12:18 pm

**** Bingo ****

In automotive world the voltage is fixed at 12V.
In AC world the voltage is variable (110, 220, etc) so they list power.

The battery at 80 Ah is 80 Ah x 12V = 960 Wh

Add 20% loss for in inverter and temperature ~ 760 Wh

If you have a 100W per channel stereo amplifier, it will likely pull ~ 300 W of power from the AC line to drive the speakers at high volume. A single battery may run this for couple hours. Four batteries could go eight hours.

Bottom line is this: read the tags on your equipmment for maximum power draw at the AC line, get an inverter with 30% more power output. Then figure out the number of batteries you need for the time window you want.

Sync · Post by **Sync** » Thu Aug 13, 2009 8:02 am

I have been running the battery-inverter generator set-up for the last two years. In reality if you want a better idea of your battery life and have the time, set up with the approximate power draw on a warm day and run it down, or at least for the length of time you will be off gen power. Heat is a factor, but this should get you a ball park estimate of battery time.

Simon of the Playa · Post by **Simon of the Playa** » Sat Aug 15, 2009 6:08 am

FUCK!

i thought this thread was about mixology and how to properly make an Atavan-Thorazine martini.

wedeliver · Post by **wedeliver** » Sat Aug 15, 2009 6:22 am

I thought this thread was about mushroom tea that doesn't make you laugh. you know, that silly laugh... hahhahahhaahhahahahahahaahahhahahahahahahaha

(nice colors)

MikeVDS · Post by **MikeVDS** » Sat Aug 15, 2009 7:43 am

If 256 a/hours is correct for a 12 hour rate, that works out to about 256 watts per hour.
21+ amps X 12 volts = 256 watts/ hour

256 amp/hours divided by hours = amps per hour

Remember temperature is a factor.
And rate of use.

Ugh. Messy messy units there. Watts is already a unit that includes time, so there is no watts/hour it should just be watts. I'm not sure what you mean by amps/hour divided by hours, I think you mean that AMP-Hours divided by AMPs gives you the number of hours the system will run or Amp-Hours divided by hours give the number of AMPs you can draw for the number of hours you divided by. Messy messy units. AMP/HOUR ("/" means divided by) is completely different than AMP-Hours (amp hours "-" is not a minus sign it's a hyphen meaning multiplied by).

gyre · Post by **gyre** » Sat Aug 15, 2009 9:28 am

I didn't understand their use of watts, so...
Trying to clarify.

MikeVDS · Post by **MikeVDS** » Sat Aug 15, 2009 9:45 am

i meant that amps arent the standard rating used in ac for stating the amount of energy used. on the meter the number they measure is watts on your devices the number given is watts you are charged by the killlowatt hour.

where in dc they state on the power supplys that it is 12 volt 7 amps and you dont see to often a 12 volt or dc power suply that is rated in watts. it is just a diffrence in the standard not a diffrence in the science.

AMPs are actually the standard for people who do electrical work, watts is more standard for things people would go to bestbuy to get. Circuit breakers and fuses are rated in AMPs not in watts because it is the current (AMPS) that will melt the wire, fuse or trip the breaker, so that's also how you size devices to be installed in a circuit, not in watts. Also when you're working with 3-phase, the formula for computing amperage from wattage is too complex to be practical to always convert; it's the amperage that is needed to correctly size the wire and breakers. So you pretty much always refer to 3phase equipment in amperage. Most name plates on equipment list voltage and RLA (run load amps), LRA (locked rotor amps), and horsepower, without even listing wattage.

wedeliver · Post by **wedeliver** » Sat Aug 15, 2009 2:11 pm

I thought the community might benifit from this information.

How to get AAA batteries out of a 9v transitor battery, keep that mp3 player working

and then there is more

http://www.metacafe.com/watch/yt-s_8n2Q ... tery_hack/

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