Category Archives: sound system

2013

image

2013 was looking to be pretty exciting with the St. Patricks Day parade and the Easter sunrise service working so well … Though I was a little behind schedule with my plans to get meters installed and upgrading the wiring on all of the battery systems.

The rest of the parts had arrived … Finding time to install them was another story.

More shows, putting another battery system together and getting the meters installed in three of the systems kept me very busy through June … And I was starting to get some data that seemed to make a lot more sense … But I still had lots to learn.

One of the battery banks with the TRIMETRIC 2025 battery meter installed.

One of the battery banks with the TRIMETRIC 2025 battery meter installed.

I was planning on using the 2013 Elma Lewis Playhouse in the Park series to test how feasible the project really was. I had hoped to solar recharge all of the batteries between the weekly shows this year … And had ordered an MPPT (Maximum Power Point Tracking) solar charge controller to do it with … After doing a little math it seemed like my three 120 watt solar panels would be able to capture enough sunlight to recharge all the batteries during the week … Even allowing for a 50% operating efficiency … Something I hoped would be a conservative estimate … Especially with rain and clouds being a fairly common occurrence here in the Boston area.

My initial plan of setting up the solar panels and batteries on site for the series turned out to be a little naive … I had to scramble a little to get a “Plan C” up and running … My truck would be parked from Wednesday night until Monday afternoon and with a little help and a couple of tall ladders the solar “array” would be strapped to the top of my truck, the charge controller hooked up… And … Time would tell.

image

PS … It worked great!

Easter Sunrise Service, Castle Island, Boston.

In the mean time …

Easter sunrise service on Castle Island in South Boston …Wow!

The view to the east is amazing. I am not going to try to describe it, but it is worth getting up early for … At least once!

I had been providing the sound system for the event for a couple of years and had really enjoyed setting up the sound gear in the dark and watching the new day arrive.

Easter morning view from Castle Island

The airplanes are not landing at Logan airport across the harbor at 4:00 in the morning and you can actually hear the harbor, the sound of the waves hitting the shore, some large ships going by … Add the flash of light from Boston Light and the slightest hint of change out on the horizon … It is very nice!

This year I had asked my contact with the Castle Island Association if I could try powering the event with one of my solar powered battery rigs and he said yes!

Normally … By the time most of the people arrive for the Church service the generator is already running with its constant drone covering up everything but the “red eye” flights coming in and the occasional overhead sea gull.

This year the first sound breaking the harbor “soundtrack” was the “Good Morning” from the priest celebrating the Mass … I’m sorry if it startled anyone!

The system ran for 2.5 hours and used .35 kWh of power … a tiny amount by any standard. Basically the “idling” current draw from having the four wireless microphones,  mix rack and amplifier on … With no background noise to compete with, the overall sound level did not need much power to cover the audience standing an an area almost the size of a football field.

The small “solar system” I brought to power the event was about the same size and weight as the generator that I helped off load from the park rangers utility tractor in previous years. Something else to think about … Eventually!

But back to rewiring …

The battery systems had worked wonderfully at powering the events so far. But I had unknowingly been getting a little help from good old fashioned “dumb luck”.

If this project was to get out of the tinkering stage I wanted to do it without needing that help.

Adding the battery meters was going to provide some very useful information, adding fuses was going to keep everything and everyone safe … and spending a little “quality time” with my coffee pot and calculator was going to get the systems performing as well as they could … For a long long time!

To find out how long you will have to check back later … Hopefully much later!

In working with 12 volt DC power it is very important to size everything for what you are trying to do … In my case … Powering all the equipment needed for an outdoor concert.

Sizing the wire used and laying out the equipment so that as little power as possible is lost to resistance in the wiring of the system … Ideally keeping the loss between the batteries and the inverter to less than 1%

To do that I needed to use the largest, shortest wires possible.

Using a voltage drop calculator like the one found in  “rapidtables.com”  you can see what size wire you will need to use. For this part of the project I used short (18″) #2 cables to go from each of the batteries to a pair of insulated buss bars, and total of about 8′ of #2/0 cable to get from the buss bars, through a circuit breaker, fuse and shunt to the inverter and back again.

If I’m doing my math correctly I am only losing .1463 volts (1.17%) to voltage drop with a 200 amp, 12.5 volt DC load … A little more power than what you could get from a standard household 20 amp circuit.

It sounds like an awfully small amount of loss to get excited about, until you realize almost everything in a 12 volt system will shut down when the voltage drops below 10.5 volts. Losing .1463 volts from 12 volts does not seem like much … But if you only get to “play” with the 2.4 volts between 12.9 volts (a full battery “at rest”) and the 10.5 volt “shut off point” … Losing that .1463 volts means I would lose between 5 and 8% of my total power at full current … And if I wanted to keep the batteries alive as long as possible I do not want to discharge them fully … I could be losing over 10% of my power … to wire!

Yikes!

I am hoping to give you a little “photo” tour of how I wired one of the systems in my next post.

Luck of the “Irish”!

In the mean time … The show must go on … The rewiring project was going to have to wait.

3/17/2013 … If you live in Boston that date can only mean one thing …

The South Boston St. Patricks Day Parade … Where being Irish is not really required!

I got a call from Mike Majorowski wondering if my battery system would be able to power a float for his band in the parade.

Hmmmmm…..

To see if it could be done I set him up with a couple of “Kill-A-Watt meters to use at his next gig to see how much power they would need … While I started to worry about the weather. Rumor has it that batteries do not like the cold!

With the readings he got from the “Kill-A-Watt meters It looked like my smaller battery system would do the job … At least if the weather co-operated and we got that perfect 77 degree day the batteries were rated for (this is Boston … and I’ve shoveled snow in May!)

I explained my “concerns” to Mike and we decided to try the parade using my larger system … At the smaller system’s price.

We had a beautiful sunny day for the parade … If you don’t mind a little cold wind … We started sound check at 10:00 am at 28 degrees And got all the way up to a “balmy” 37 degrees somewhere along the parade route!

Five hours of run time, 1.83 kWh of power used … We even got a nice “Cool!” From the Boston Police Truck team inspecting all the floats when they asked where we were getting our power from … apparently we did not need a special permit for using a generator on the float … Cool indeed!

At the end of the day the inverter battery meters still showed 90 – 100% full … It would have been nice to have the new meters installed … The parts had arrived … the extra time needed to install them was still on back order!

It was my first event moving the battery boxes around by myself and one thing was certain … Those battery boxes are heavy … Very heavy!

The larger battery system with the Trimetric 2025 meters installed

The larger battery system with the Trimetric 2025 meters installed

The larger system consists of a pair of “Site Safe” tool boxes with each box weighing in at about 500 pounds! … So “portable” is a relative term!

Moving them from the truck to a loading dock, or in this case … To the back of the “roll off” tow truck that was used for the float was pretty easy … Pushing them up the ramp to my truck? … Not so much!

Moving them around was going to take three or four people … Or a lift gate on the back of the truck … I will need to figure that one out later …

My to do list keeps growing!

Back to the drawing board!

Oh well … It turns out almost everything I did on my first attempt at going solar was wrong.

Wrong wire sizes, wrong lengths, wrong assumptions about how a bank of batteries should be wired … All of which made for a lot of possible failures.

Overestimating how much power I would actually be using … And more than a little good luck keeping any of those failures from happening!

So … Back to the drawing board …

The first “order of business” was to get a real metering system installed … It was time to find out what was really going on with the batteries.

I needed a “gas gauge” I could trust.

The Trimetric meters from Bogart Engineering are highly recommended by a lot of folks. … I decided to try the 2025 RV model for the project.

The 2025 is a very neat device that keeps track of the power in Amps  going in to and out of the batteries … A quick look will tell you the voltage. Press a button and you will see how much power is going into or out of the batteries. Press the button again and the meter will tell you the batteries are 87% full (… Or 18% full … It might be time to start thinking about worrying … Soon!).

In any case … More information than I could have hoped for!

The folks from Bogart Engineering have designed the meters to do a lot more … But those three things were going to answer a lot of my questions … And keep me out of trouble … For a little while at least!

Adding the meters to my “rigs” was going to take some rewiring … and some math … More on that later.

Since I was going to have to get in and do some rewiring to install the meters it made sense to go in and fix as many of my wiring mistakes as possible … My good luck was only going to get me so far!

If  you’ve been following along since the beginning you may remember my first big battery powered show having some yellow “warning” LEDs flashing on one of the inverters. The band had not gotten any louder … But something had changed … It took over a year to figure out what had happened … the power in the batteries was not getting to the inverter.

Resistance was “robbing” the system of power.

The wire I was using was too small and too long for the current that was trying to get from the batteries to the inverter … Causing a voltage drop … Causing the inverter to “ask for more power from the batteries … Causing the resistance to go up …causing more voltage drop … Causing …

It was a good thing I pulled the amplifier from one inverter and plugged it into the other inverter when I did … Or that show might have been the last!

My common sense approach was not helping at all … Luck … On the other hand … Was!

When using batteries to power something you do not want to waste anything. Leaving a 60 watt light bulb on overnight will “eat up” a lot of your battery reserve. It can be done … You just need more batteries … And solar panels to make it happen.

A little common sense would tell you … If you do not need it … Turn it off!

Common sense probably won’t tell you how much power will be wasted by using the wrong wire. Too small or too long of a wire could waste as much power as that 60 watt light bulb.

When using DC power a good “rule of thumb” is always use the largest, shortest wire you can.

So … I bought a bunch of larger wire to replace the stuff I had started the project with, ordered some meters, shunts, heavy duty buss bars, fuse blocks, fuses, lugs, heat shrink tubing … and my new favorite tool … A hand held crimper capable of hand crimping up to # 4/0 cable!

I wanted my systems to perform as well as they could … The solar powered equivalent of a finely tuned sports car as it were.

I’m afraid I’m going to be  seeing lots of 4/0 in the near future …

January, 2013 … and the Flu!

January, 2013, a book to read, some questions to answer … And the flu!

“Armed” with my trusty old iBook G4 and the second last dial up internet connection on the planet …  it was time to try “Googling”again!

(I really hope I am not that last person still on “dial up”)

It turns out there is some very good information out there … Mostly hidden in between some small scale items used to charge your cell phone or iPod … and some amazing systems even I find too incredibly good to be true … But perhaps … I’m still learning here!

Searching for solar power will overwhelm you … Narrowing the search down a bit to solar powered sound will get you a lot of neat things to play your iPod on, an interesting sound art project … And if you look far enough you will find …

Www.solarpoweredsound.com

Some nice photos of a couple of portable solar power systems being used at events … But I was not able to find out more.

A lot more searching, will get you to the North Texas Renewable Energy Group’s “Solar Shuttle” … A very impressive silent portable power generator … That happens to be solar powered … Wow!

Www.ntreg.org

They keep redesigning their web site … So you may have to look a bit.

This morning (8/25/2014) I found it in the “member projects” page under “The Solar Shuttle solar trailer” link.

Make sure you check out the link to the “PDF photo journal”

Wonderful stuff to find, but no help with finding any answers to my questions.

… Until Steve Gagnon sent me a link to Handy Bob Solar!

http://handybobsolar.wordpress.com/the-RV-battery-charging-puzzle-2/

Thank you Steve! … And Bob!

Bob has been “boondocking” … living off the grid … for years … And had to try a lot of things to get a solar power system to work on his RV.

Check out his blog … But start a fresh pot of coffee and get comfortable first … He has a lot to share with anyone willing to take the time. And if you are interested in off grid solar power … find the time. What “Handy Bob” has to say is worth it!

A lot of why someone boondocks gets lost as soon as you start up a generator … The peace and quiet of the wide open spaces is easily overwhelmed by even the quietest of internal combustion engines.

Bob seems to have his feet firmly on the ground of common sense … And what he was running into trying to set up a working solar power rig for his RV did not seem to follow what his common sense was telling him … It should work … The question was why didn’t it.

Backwards from my questions by about 180 degrees … It shouldn’t work … So why is it?

My problem was that I was overestimating what was going on … Leaving me with extra power at the end of the day … In the RV world … It seems that underestimating what was going on was leaving a lot of people with not enough power at the end of the day.

I have the easier problem to solve.

I have learned a lot … And will continue to learn  from Bob and the other folks out there who have taken the time (and spent the money) figuring out how to make off grid solar work.

Thank you all for sharing!

Now to put some of those lessons to work!

When in doubt … “Google” it!

I obviously needed to learn more about things … But how?

When in doubt … “Google it”!

Hmmmm …. Well … It was worth a try!

I’m not very tech savey … (Said as I sit here writing a blog on an I-pad!)

Getting around on the internet and finding what I was looking for has been a hit or miss proposition for me.

And having a smart phone that does not like me does not help things

… But I digress ….

My first attempts at learning about solar power and batteries on the web did not get me very far.

However … The folks at Boats and Motors sold me a wonderful book about how an electrical system works on a small boat!

The 12 Volt Bible by Miner Brotherton and revised by Edwin Sherman, full of lots of great information about DC power and batteries … And the occasional mathematical formula for us math fans out there (out there … A pretty good way to describe …)

Originally written in 1985 and revised in 2003 … It turned out to be a great place to start.

The boating world is a really good place to find both hardware and information … It is one of those places where being a little wrong can get you into a lot of trouble. The kind of reliability needed in the boating world is what I wanted / needed for this project.

In the entertainment world … failure is not an option!

The help I received from Boats and Motors and West Marine was wonderful … they were very happy to share what they knew and if they did not know, would try to find out … And if they were not able to come up with an answer, would apologize for not being able to help!

I really like these folks!

So lots of questions and a book to read for when things with the “day job” slowed down.

I had a busy fall into New Years season ahead of me and nine months until my next booked solar powered gig … So I “moth balled” everything … With a somewhat regular schedule of “top off” recharging to keep the batteries from an early death (I did get far enough into the 12 Volt Bible to learn that much).

Made it through the year … With what had become a wonderful tradition of ending the old year mixing the Concert for Peace at St. John the Divine in New York … And the quiet drive back the next day.

If you ever get the chance to … Go!  … It is an amazing event!

2012 had been a good year … Some amazing shows …  It was great to be involved with the Urban Nutcracker again … and everything about the solar project had been a lot of fun … My dad and I working, almost non stop to be ready for that first solar powered Elma Lewis Playhouse in the Park “gig” … a 2:00 in the morning close encounter with a skunk kept things interesting!

I was truly amazed at what the batteries were able to do.

At a street fair in Andover I  “caught” one of the crew from the main stage down on his hands and knees looking to see if I had a power cord coming up from the manhole cover I had “parked” one of the battery boxes on top of.

Apparently I was not the only one being amazed!

11 events running over 42 hours … without running out of power … I was able to record 19.03 kWh of power used … It took a while to realize this was going to work and I should be taking notes … I missed three of the early shows.

Photos would have been nice too!

In any case … January was looking promising for figuring things out … A couple of quiet weeks … and the flu.

2012 Elma Lewis Playhouse in the Park.

It had been a bit of a rush to put the new battery bank and inverter system together.

With no time to add solar panels for the much larger system, a plan “B” was going to be needed for recharging the new battery bank.

Christine from the Franklin Park Coalition came to the rescue!

She made a couple of phone calls and a place was found in the Franklin Park Zoo maintenance yard where the battery boxes could be parked between shows to plug into the grid and recharge each week. Not exactly solar powered … But we would not be needing a generator for the series!

Everything was ready … Well at least everything seemed ready …

The morning of July 10, 2012 started off nicely … sunny and warm.

A local community group had agreed to provide the sound system for the morning events and everything was sounding great … But when a third self powered speaker for the stage was added, it buzzed … a lot.

The poor stage monitor was not even close to happy.

After checking the cables to see if a bad connection was causing the noise,  running a power cord to the new battery / inverter system to see if that might help … and watching the clock tick as show time got closer and closer … I pulled an amp and speaker from my truck, set them up and turned them on … The silence was golden!

Something about that self powered speaker did not like the battery / inverter power.

The rest of the morning show went smoothly, with the smaller solar powered system running for a little over two hours, using .23 kWh of power  (according to the “kill a watt” meter), with the inverter’s battery meter still showing “full”!

And … aside from the buzz … a success!

The evening show, with one of my sound systems, started out fine.

I had hired Clara Rhee to mix the show so I could keep an eye on the battery systems for their “shake down cruise”. No hums or buzzes showed up in the sound system or on any of the band’s gear,  but the battery powered LED lights that had been rented for the series were not going to be able to compete with the evening sun as it set.

As the concert progressed the meters on the 1,250 watt inverter powering the PA started to blink yellow on some of the louder parts. … The meters on the 2,000 watt inverter powering the stage seemed fine …. So I warned Clara, and in between songs (with fingers and toes crossed) I unplugged the amplifier powering the six stage monitors from the smaller rig and plugged it into the larger rig …

No sparks, smoke or buzzes … or blinking yellow lights.

I don’t think anyone noticed … though someone may have wondered what the huge sigh of relief coming from back stage was for!

Did I mention that batteries are very heavy!

The two battery / inverter systems used to power the 2012 Elma Lewis Playhouse in the Park concert series. The smaller system was recharged each week using two 120 watt solar panels.

The concert ended as scheduled … 3 hours and forty five minutes after we had turned everything on for sound check … Using a total of 3.49 kWh of power between the two systems …. Most of that coming from the smaller system powering the PA.

My assumptions about how much power would be needed for the PA and the stage were way off base … But nothing that could not be fixed by just swapping power sources and loads … The morning’s buzz had me a little more concerned … It looked like I would be visiting the electronic supply store again in the morning!