Guidance on using deep cycle marine battery for power at BM

alt12 · Post by **alt12** » Tue Apr 01, 2008 1:53 pm

We are looking at using a deep cycle marine battery to power a mobile sound system at BM. Has anyone used marine batteries for AC power? Any suggestions / recommendations? My main concern is around efficiency loss from using a DC/AC inverter and whether or not the battery can provide enough power (600-800 watts over 6-8 hours continous between charges)... Thanks,
alx

Dork · Post by **Dork** » Tue Apr 01, 2008 3:07 pm

Let's see... figuring 800 watts out of the inverter means around 1000 watts from the battery due to loss during conversion, so 83 amps for 8 hours, which is 666 amp-hours at the 8 hour rate. According to this table (I have no idea how accurate it is) only the last battery listed would have enough capacity:

http://www.windsun.com/Batteries/Batter ... 20Capacity

And you still need access to a generator of some sort to charge the thing during the day. I'd say just plop down the cash for a Honda EU1000i or EU2000i and forget the expensive battery and inverter. Batteries are great for small or occasional loads, but not always good for sustained loads like you're looking at.

phil · Post by **phil** » Tue Apr 01, 2008 5:42 pm

Watts = volts x amps

Say 800 watts (assuming that's the drain in current, not the rated power output of the sound system) means

800 = 12V x X amps
800/12 = 66.6 amps. So you'd need a 66.6 amp battery to deliver 800 watts for one hour. Yep, one hour. Factoring in the loss through an inverter, I'd say Dork's in the ballpark.

Now here's another problem - you can't charge a battery in an hour or two. The suggested rule is to divide the capacity of the battery by 10 - so a 66 amp-hour battery should be given 66/10 = 660 milliamps to charge it. Depending on the state of discharge, this would take 12 to 15 hours to recharge. Using more amperages to charge a battery evaporates the fluid in the battery - this causes damage to the lead plates. This means you wouldn't be able to charge more than a couple of 66.6 amp-hour batteries a day with one charger. (I have a 100 amp-hour battery, and it weighs 70 lbs., by the way.)

I'm thinking Dork is right again on his suggestion to get a generator. Cap'n Goddammit has a post somewhere on how to hook up external fuel tanks to gennies so you never run out of fuel. Be careful how you store your gas, though.

Captain Goddammit · Post by **Captain Goddammit** » Tue Apr 01, 2008 7:49 pm

External fuel tank setup for Honda generators http://ilynne.com/captaingoddammit/
But I'm starting to think there's a better way to connect the fuel line to the gas cap.

I think the battery will fall short trying to hold that kind of a load for that long. Possible options are to use several batteries in parallel, or do what has already been suggested and get a Honda or Yamaha super-quiet generator. They only weigh as much as a big deep-cycle battery, are very quiet, and with your sound system going you won't hear it at all!

When you say "mobile sound system", do you mean totally portable, or on an art car? If you're on a vehicle, and can handle a little light fabrication, set up an alternator that is overdriven 2 or 3 times normal speed, so that at idle (normal BM speed) it'll be at full output. You'll want to remove the belt for regular driving, if any. If you use a 100-amp alternator, it just might keep you lit.

gyre · Post by **gyre** » Wed Apr 02, 2008 3:53 am

They make batteries big enough for this but it does sound like a generator would be easier.
They make some very big alternators for cars- over 100 amps at idle.
Much cheaper rebuilt and very reliable.

Caine · Post by **Caine** » Wed Apr 02, 2008 11:12 am

It is *always* easier to use a generator and lug in fuel than to use electric only, powered by renewables. *Always*

That being said, check these out:

http://www.batteryweb.com/ub_slavrla-de ... %20AGM.htm

if you have the cash and the load capability, 4 of these will give you 6-8 hours of trouble free use for an 800W setup, and you won't have discharged them past about 50%, which is good since you can charge them back up a lot faster from 50% than from 20%. And they don't take much damage if you don't cross the 50% boundary. They are AGMs so they are pricier, but they have no acid to leak or spill and the Playa will not be able to hurt them. If you actually want to buy some, look around online for the model number. I've found them for a steal from some wholesalers from time to time.

To recharge them over 12 hours you'd need around 1KW of generating capacity, or maybe one wind turbine and some solar panels.

You could also get some of these:
http://www.batteryweb.com/usbattery-det ... S-185%20HC

THOSE babies are the mother lode. I'll let you do the math! They don't have as much capacity as the 8D's, but they are lead acid standards, so they will be cheaper. Also, U.S. Battery has distributors all over the country, so you should be able to drive and pick them up yourself.

Or one genset. Did I mention it is always easier to bring a genset?

Then again, it is easier to burn down a forest to farm than it is to practice silvicultured mixed farming. One is easy, destructive and cheap.. the other is tough, sustainable and pricey.

Choices!

Post by **mdmf007** » Wed Apr 02, 2008 2:41 pm

When you say mobile are you on an art car, or on a non powered unit.

If your on an art car - i would do what Gyre suggested and add an alternator and inverter.

If your on a non powered unit Id go with the Honda generator, use it for BM, and sell it when your done. youll be able to recoup at least 70-75% out of the generator.

Batteries are just one of the most inefficient ways to power something, especially when you add an inverter.

StevenGoodman · Post by **StevenGoodman** » Wed Apr 02, 2008 2:47 pm

Caine wrote:It is *always* easier to use a generator and lug in fuel than to use electric only, powered by renewables. *Always*

This assumes you can't bring in enough batteries for the whole week? At BM2006 I ran 6 ultra-bright LEDs off 35Amp-hour battery for the whole week (by using a light sensitive relay to shut it off during the day). Was 35Amp-hour/350mA = 100 hours / 12 hours per day = 8 days (and I only needed 7). (and a 9v battery to run the relay.)

Two heavy batteries, but much easier than a generator!

I would need to want 3-4 times as much light to mess with a generator. Now, this was a very low power setup. For energy density it is hard to beat gas or diesel.

Martini Steve

Captain Goddammit · Post by **Captain Goddammit** » Wed Apr 02, 2008 10:18 pm

It's "always" easier to say how much greener a ridiculously expensive solar and wind setup would be than it is to pay for it, or to get it to deliver enough wattage! This is just a temporary, short-term use. The amount of fuel a small Honda genny will use in that time is a drop in the Burning Man trip bucket.
If it's an artcar we're talking about, the true green setup would be to re-use existing old car alternators driven off the engine that is already idling away, otherwise wasting most of it's power.

Caine · Post by **Caine** » Thu Apr 03, 2008 9:57 am

Captain Goddammit wrote:It's "always" easier to say how much greener a ridiculously expensive solar and wind setup would be than it is to pay for it, or to get it to deliver enough wattage! This is just a temporary, short-term use. The amount of fuel a small Honda genny will use in that time is a drop in the Burning Man trip bucket.
If it's an artcar we're talking about, the true green setup would be to re-use existing old car alternators driven off the engine that is already idling away, otherwise wasting most of it's power.

Hey I wasn't judging on anybody Captain! That was my whole point.. it is true that it is easier, and cheaper, to use a genset. It's also true that the amount of fuel required to get to burning man is more than the amount you would burn while you're there (unless you are a serious pyro).

BUT, if you wanted to lighten your impact and move closer towards the Ideal (Self Reliance) then it only takes effort to go the extra mile.

Solar can be expensive, yep. But you can also scrounge old solar panels, repair them and get them working pretty easily for minimal money (I've taken 20 year old panels that were being thrown away and repaired em, losing only maybe 10% capacity). You can also build your own wind turbine from nothing but scrounged materials. Old washing machine motors, alternators, etc. Personally, I like going as far as I can with this and making my own prime mover from magnets and wire. Blades carved from some old railroad ties. Fittings from pipe clamps or lots and lots of zip ties. You can get deep cycle batteries from the manufacturer that have been "damaged" (just the posts).. repair em and you are only paying 1/2 price. The only stuff you would have to actually pay full price for are things like the inverter/converter and the battery charger, and maybe some wiring. Even then, you should be able to find that stuff used, or as surplus.

For me it's not about the ideal setup.. its about creating something from nothing. There is no way in hell I could EVER build an ICE from bits and bobs. The only reason it is cheaper and easier is because of mass production. I like the Radical Self Reliance feeling I get when I am getting power from power sources I paid almost nothing for. In fact, our house is starting its journey to be completely self powered!

And that's my whole point, I think. Well, I'm sure I have other points.. I'm kinda pointy. But this one.. this one I think I've polished clean. Maybe.

NEW POINT: I found another point.. do those things grow by themselves? You could get a small diesel genset and run it on biodiesel! That would green you up 1/2 way, since you're still emitting noise and air pollution. :-) Actually, I have a diesel car and am planning in making at least half of my trip biofueled.

For more info on biofuels, there are huge numbers of sites out there, but this one is particularly good I think: http://journeytoforever.org

phil · Post by **phil** » Thu Apr 03, 2008 11:36 am

Solar powered generator weighs a ton. Literally:

Three 200-W solar panels put 600 watts into the 1200 amp-hours of batteries (six 200 amp-hour marine batteries). No price is given. Shipping is FOB Maine. (FOB means they'll put it on your carrier, whatever that is, at their factory. From there, shipping costs are up to you.) Output is stated as 3500 VA at 110 Volts.*

You can add an optional bank of batteries for another 1200 amp-hours of power, but they don't say what that weighs.

*Apparent power is (rms Volts) X (rms Amps). If volts is 110, and power is 3500, 3500 / 110 = ~32 amps.

Watts is amps X volts, so the output wattage here appears to be
32 amps X 110VAC = 3520 Watts
(There is a difference between "real power" and "apparent power.")

The original poster wanted 600-800 watts for 6-8 hours.

800 watts X 8 hours = 6400 watts

so he'd need the extra battery pack for a day's dancing. (Assuming my calculations are correct, which they sometimes are not.)

gyre · Post by **gyre** » Thu Apr 03, 2008 11:43 am

I think it also refers to who is responsible for the condition.
It can be risky for the purchaser in some cases.

Captain Goddammit · Post by **Captain Goddammit** » Thu Apr 03, 2008 2:40 pm

Caine, that's pretty cool stuff!
Although in this particular instance, and making the blind assumption that we're talking about an application aboard a mutant vehicle, I'd still vote for using otherwise already wasted energy from the idling engine to turn extra alternators as the greenest.

alt12 · Post by **alt12** » Mon Apr 07, 2008 11:09 am

thanks for the suggestions...my preference would be to just get a generator...seems easier and way more efficient, however, we are going to be lugging this around on a bike trailer so the exhaust fumes are really the issue... might have to do multiple batteries in serial or something like that....but then the weight becomes a factor....sounds like no easy solution here...

Captain Goddammit · Post by **Captain Goddammit** » Mon Apr 07, 2008 5:28 pm

A little Honda won't give you any exhaust fume issues out on the playa, and weighs the same or less than the batteries would. You'll love it.

gyre · Post by **gyre** » Mon Apr 07, 2008 5:46 pm

Can you reduce the power demand?

alt12 · Post by **alt12** » Tue Apr 08, 2008 2:29 pm

well maybe I'm being overly ambitious regarding power consumption....I'd like to power 2 250-500watt amplified speakers and roll around the playa and bring people back to our camp parties where I'll be able to plugin to our main soundsystem to provide extra wattage... I know that 250watt speakers don't necessarily use 250watts in power....I was looking at Yamaha Stagepass 500s, which are 2 x 250watt (peak) active speakers and the specs say around 65watt power consumption.....

From what you guys are saying, I could conceivable put a 1-2 100amp-hour batteries and use that for a couple of hours....sure seems like generator is the way to go though...plus those batteries are heavy as shit!

phil · Post by **phil** » Tue Apr 08, 2008 2:44 pm

> I know that 250watt speakers don't necessarily use 250watts in power

_Way_ less, which may alter the equation vis-a-vis battery vs. generator. 65 watts consumption divided by 12 volts is about 5 and a half amps, say 6. My hundred amp-hour battery would give over 16 hours of power, say 15 to take into account inverter loss and such.

You'd get a day out of that, but you still have to recharge. And the battery still weighs 70 lbs.

gyre · Post by **gyre** » Tue Apr 08, 2008 4:55 pm

Look for efficient speakers first.
Eighteen inch speakers exist in 100 decibel sensitivity.
Horns can go way past 100 db.
And sound carries really well out there.
You don't need a lot of volume, just get clear undistorted sound.

Trishya333 · Post by **Trishya333** » Thu Jun 12, 2008 3:13 pm

I have 2 deep cycle batteries, a 48 and 56 (40 and 50 lbs). I also have a sine wave inverter rated at 800 wtts. a couple of trickle solar chargers, but at (I think 3 volts and .5 amps or maybe MHamps,) not too usefull for rechargeing a major load loss).
my question would be the oppossite. what is the most efficient sound system, better then a boom box . I know that the amp sucker is the bass sound/ frequency due to the enrgy it takes in the lower numbers (gee 15- 25 Hrtz would be nice).
how about a powered computer type set up? or a bigger boom box? recomendations of good boom boxs?

I hate most of the electronic night music and plan to stay at camp sometimes listening to my own downtempo or chill house music.

any ideas for good ish sound and bass response with my power specs?

if anyone likes deep house you can hang out with me!

(if I go, oops)(not sure yet)

motskyroonmatick · Post by **motskyroonmatick** » Thu Jun 12, 2008 6:55 pm

How about a computer speaker setup with the input that is a mini jack so you can connect the iPod to it. I'm thinking of the kind that have two desktop speakers and a below desk sub woofer. I think mine is 120volt power. It is by Logitech and really kicks ass!
Try before you buy!

gyre · Post by **gyre** » Thu Jun 12, 2008 9:14 pm

Trishya, how loud do you want it?
How much do you want to spend?
How much power do you want to use?

Make sure the inverter is able to deliver what you want on a steady basis and that it has a clean enough signal for your equipment.
Ratings are often puffed up.
Depending on the inverter, there is some loss when connected and in use.

Trishya333 · Post by **Trishya333** » Fri Jun 13, 2008 10:15 am

I'm set! loudness was not a factor, or issue. My goal is to have a fairly clean low frequency bass from a portable device which will be behind my chair. I did alittle research and bought a kabbom 52 watt boombox by jvc. it has 2 independent 6 inch subs and it's bi amped which (to me) means a decent speaker set up. also has aux in, so I can have a master source split into my other sat speakers boomboxs. And they all can run on a 12 volt direct set up so I might not need the noisy inverter, depending on the energy needs.
it's also possible I will find music I like somewhere at night. or maybe even sleep (what a odd thought) and I have a friend (who will camp with us (at Pink mammoth) with a solar audio bus which totally rocks . he will play house for me, at times, too. (he has a solar array on the roof that trickle chrges the 4 big deep cycles that power the great stereo).
so thanks for ideas. it helped just to see this topic and think about it alittle.
love that stuff

Post by **AntiM** » Fri Jun 13, 2008 10:27 am

I've never felt the need to play my own music out there, there's enough ambient sound and waves of music to fill my ears 24/7. When I get tired of it, I stuff in the earplugs. May not be my favorite tunes, but going outside my comfort zone is often good.

griffin · Post by **griffin** » Mon Mar 23, 2009 3:55 pm

I'm trying to power lights on an art installation. All LED, adding up to less than 100 watts. I want to run them from dusk to dawn. I want to run it all on 12 volt battery power. I have access to a 20 watt solar panel to charge it. Also have a charge controller. And a 400 watt inverter.

I'm really confused when it comes to amps, volts, and watts, and the simple equation isn't really helping me figure out what battery to buy. The first priority is to make the lights run all night. Second is to charge it with solar (I have other charging options if necessary).

As best I can tell, 100 watts is 8.9 amp hours, so does that mean I would need an 89 amp hour 12 volt battery to run the lights all night? Am I on the right track?

Also, will I get more out of the battery, if the inverter is closer to the actual power need? Does that make a difference. Is there a website out there that explains all of this in a way that burners can understand?

dragonfly Jafe · Post by **dragonfly Jafe** » Mon Mar 23, 2009 4:43 pm

griffin wrote:I'm trying to power lights on an art installation. All LED, adding up to less than 100 watts. I want to run them from dusk to dawn. I want to run it all on 12 volt battery power...

watts = amps X volts

assume 100 watts load at 12v, that comes to 100/12 or 8.3 amps. Assume dusk til dawn = 12 hours (6pm-6am). The power required is therefore 8.3 amps x 12 hours, or 100 amp hours. You never want to draw down a deep cycle battery more than 50% if you can help it (prolongs the life), so 200 amp-hours of battery capacity would be needed. This is either a BIG battery or two regular deep cycles hooked together. If you do two batteries make sure they are the same brand, type, and size (or there can be charge/discharge issues).

Why do you need the invertor? That "inverts" 12vdc into 120vac. Do the LEDs run off AC power?

a single 20 watt solar panel will not do much. assuming 100% total efficiency (which you will not get), a 20watt panel would take 5x as long to charge as you want to play (100/20=5). So for a 12 hour night-time light, it would take 5 days (60 hours) of charging. For a 100 watt load you are going to need 150-200 watts of solar panels. minimum. This is one full sized panel (or two medium sized ones). And if you don't want to continuously move them, and keep them spotless clean, add another panel.

phil · Post by **phil** » Mon Mar 23, 2009 5:03 pm

> so 200 amp-hours of battery capacity would be needed.

That's per day, let me make clear.

For information on charging a battery, take a look at
http://www.cieux.com/bm/batteryWreck.html

Charging a battery often takes longer than discharging it, and you need a charger that works with your size battery: too small a charger,and it'll never charge the battery; too big a charger, and it may never sense enough resistance in the battery to switch from "charge" to "float" (which maintains a charge without overcharging). See the batteryWreck article for much more information.

If you want to recharge with solar panels, I'm sorry to say you need more than solar panels. You'll need a charge controller, too. If you don't have a charge controller, the panel may overcharge the battery, and if the sun goes down or behind a dust storm while the panel is hooked up, a controller keeps your batter from discharging into the panel. See this site

http://howto.altestore.com/How-Many-Sol ... ar-Ar/a88/

for guidance in calculating how many solar panels/watts you need.

Good luck, and have fun. There are problems, but they're not insurmountable. You need to work this out to see i fyou can afford your system.

Post by **mdmf007** » Mon Mar 23, 2009 8:39 pm

griffin wrote:I'm trying to power lights on an art installation. All LED, adding up to less than 100 watts. I want to run them from dusk to dawn. I want to run it all on 12 volt battery power. I have access to a 20 watt solar panel to charge it. Also have a charge controller. And a 400 watt inverter.

I'm really confused when it comes to amps, volts, and watts, and the simple equation isn't really helping me figure out what battery to buy. The first priority is to make the lights run all night. Second is to charge it with solar (I have other charging options if necessary).

As best I can tell, 100 watts is 8.9 amp hours, so does that mean I would need an 89 amp hour 12 volt battery to run the lights all night? Am I on the right track?

Also, will I get more out of the battery, if the inverter is closer to the actual power need? Does that make a difference. Is there a website out there that explains all of this in a way that burners can understand?

Heres what i was thinking -
As stated above - the 20 watt panel may put out 20 watts but at what voltage? if it is at 12 volts DC (most likely) this will net you 1.8 amps. not a whole lot going into your battery.

Distance is a major factor in DC power transmission. DC is horrible to transmit over lines. Why? DC current being Direct - meaning no pulses but a steady flow creates a lot of resistance. This resistance will be in the form of heat. Basically you create a heating element when you try to transmit DC current over distance. You would be lucky to get 70% of your power through a 100 foot extension cord in DC 12v. The rest will simply be heating the wire. You could test at home with an Ohm or Voltage meter

You could charge a battery in your car rather quickly if you put some quick connections inline - im thinking in less than an hour. Car charging systems are made to recharge a battery quickly, and depending on vehicles can put as many as 200 amps out.

With DC current - larger wire is better, Clean Large Connections, Power source as close as practical, Surface area for contacts counts, Clean Terminals are best.

Bluemandrew · Post by **Bluemandrew** » Wed Mar 25, 2009 6:05 pm

I've been trying to figure out how to power a laptop powered time lapse photography setup. Ideally I'd like to run it from when I get there to when I leave, but more and more this seems to be a monumental undertaking.

The laptop has a 11.1V/4800mAH battery in it, and it runs for about 3 hours on it's own. It seems to me like I'd be hard pressed to run that 24/7 for 7 days without an expensive battery set up and a nice gennie.

Am I right or can one of you lovely eplayans give me some sort of hope for this project?

phil · Post by **phil** » Wed Mar 25, 2009 7:36 pm

> the 20 watt panel may put out 20 watts

but what does it _draw_? When the post says LEDs are 20 watts or 100 watts, my guess is that that means the total light output is equivalent to a 20W or 100W incandescent bulb. I'd want to know what the system draws - LEDs, resistors, wiring, etc.

Bluemandrew -- it's the math. Somewhere on the back of your laptop, look to see if there's a statement of what the laptop draws. Knowing the battery is 4800mAH is interesting, but you need to know what the laptop draws in power. I'm looking at an old iMac, and it says "1.875A max." So if I want to run the iMac 24 hours a day for 7 days, that's 168 hours that I need to feed it 1.875 amps. So I need 168 x 1.875 = 315 Amp-hours.

My iMac battery is 4400 mAh, so discharging 1.875A gives me (rated capacity/current drawn = time) 4.4 A / 1.875 Ah = 2.3 hours. The college way to state the formula I just solved is Q/I = t, where Q is the stated battery capacity, I is the current drawn, and t is time.

You know what your time is (168 hours) but you don't know the current drawn. Let's suppose it's 1.875.

Q/I = t
Q = t*I
Q = 168 * 1.875 = 315Amp-hours

Now you know the formula, you can figure out how many batteries at what capacity you need. I'd recommend 4 100-Ah batteries, if you're not going to recharge.

If you are going to use a generator to recharge, see
http://www.cieux.com/bm/batteryWreck.html
about recharging. If you recharge too fast, you boil off the acid solution, damaging the battery. It can take 12 to 15 hours to recharge a battery properly.

Your shopping list may include the following: generator if you're going to recharge; a reliable battery charger if you're going to recharge; a couple of 100Ah batteries if you're going to recharge, four of them if you're not; an inverter so that you can plug your laptop into the inverter to charge that battery. (You'll lose amperage powering the inverter as it converts DC to AC, and you'll lose power with the wallwart charging the laptop as it converts from AC back to DC.)

Good luck, and have fun.

Big batteries like the hundred Ah batteries are available at Costco for under a hundred bucks, as I recall.

Guidance on using deep cycle marine battery for power at BM

Guidance on using deep cycle marine battery for power at BM

more questions re deep cycles and sound systems

thanks for the replies

Along the same lines