Van Upgrades and Spring Heat

As you saw in the last post, I have been doing a lot of work on the van.

• Pulled out all the seats in the back
• Placed insulation on the floors and walls
• Put down a wooden floor
• Added a roof vent with a built in 12V exhaust fan.  
• Added 4x 175Ah deep-cycle batteries in 24V array (2 parallel banks in a series circuit)
• Added a 180W 24V solar panel
• Added a Xantrec C35 24V charge controller
• Added a 24V 1500W inverter
• Added a 24V to 12V converter
• I have replaced the air mattress with a foam mattress

All this expensive stuff is going to seriously reset my equipment cost breakdown.  I hope to be updating that soon once I tabulate all my receipts.  All in all, I expect I easily crossed a $2000 mark.

Now, with all these improvements, I plan on being able to be "generator free" this summer.  I have also purchased a Frigidaire 5200 BTU AC that will consume < 500W when running.  It also has an energy saver mode that will kick off the compressor and operate a fan.  I am very excited to see how everything works together.

The downside: This week, I did not have either air conditioner in the van.  Temperatures Mon-Wed peaked in the 90Fs, and according my thermometer and others, reached 100F over the parking lot.

The upside: The insulation and exhaust are definitely doing their trick.  Previously the van would heat up approximately 20F more than the outside.  If it was 60-70 outside, I would get 80-90 inside.  It was a tin oven.  For this week, it was hot but understandably so.  Monday: temperatures outside showed reaching 97F on my thermometer.  Inside the van peaked around 92F.   On Tuesday, the situation worsened.  At the peak (around 1-2PM), the temperature outside reached 100F while inside went to 102F.  Unbearable even with the fans blowing all the air around.  Today however, was somewhat nicer.  The temp still made it up to 98F outside, but inside stayed about the same or a 1-3 degrees less.  It was hot, but the humidity went down to 26%.  Normally, it is 35% inside the van.  The lower humidity made it bearable, even comfortable inside.

Another downside of running fans is that you have to be careful how you sleep.  If your mouth is slightly open, it will dry out from all the air rushing around.

Now that the major work is done, I will be able to leave the van stationary again, prolonging the vehicle's life and reducing my gas expenses.  Currently, it sits around 127k miles, which isn't much for a '93, especially with the truck engine inside it.

Remodeling photos on Flickr

Over the last couple weeks, we have done some serious remodeling to the mobile apartment.  The van seats have been ripped out, insulation has been added, new flooring is in place, and a nice paint job has taken place.  Additionally, a solar panel and battery box combo have been installed.

Check out the remodel on Flickr.

Inverter and Air Conditioner Test

UPDATE:

The confusion below regarding AH and run time has beencleared up.

A 175Ah battery provides 175A @ 12V (2100W) for 1 hour. 
The portable 9000 BTU air conditioner actually pulls 9-10A @ 115V (900-1000W) (giving it an EER or 9).   However, my inverter is rated at 1500W with a peak of 3000.  I believe at the moment the compressor kicks on, it pulls around 2000W and exceeds the batteries capabilities, coupled with losses from the inverter.  It would be an interesting idea to take a fully charged starting battery with a high CCA rating to see if it could activate the compressor for a few minutes.


I have ordered a 5100BTU air conditioner with an 11.7 EER value.  This should pull 435W when the compressor is running.  It is a window unit, so I'll have to make a special box/duct for it.

Fun Fact: Take an air conditioner's BTU and divide it by its EER to get the electrical power usage (watts).



=======================

Today (at home) I did a somewhat expensive test.  I connected to 175Ah deep-cycle batteries in series to a 24v / 1500W power inverter.  I then used this to power my air conditioner.

A few things first.  It's 30F outside, so this test would not work in my van.  I discovered it wouldn't even work in the basement of my house (too cool).  I left it running for 4 hours in my basement connected to the battery/inverter.  It was running great.  So great that I couldn't believe it.  After 4 hours, the voltage from those two batteries was holding at 22.75.  I hooked up my kill-o-watt and discovered I was only pulling around 100W, sometimes less -- it was using about as much as a bright light bulb.  I had been taken.  It was just pretending to run.  In the process, it caused me to run the fan against my batteries for 4 hours, reducing their fully charged status.

So ultimately, I had to bring it up and set it next to my radiator.   First, I ran it on the utility power.  This time, the  kill-o-watt showed 600-650W, on occasion kicking up to 750W.  Not bad.  I then brought up my battery setup and ran it off of that.  Similar wattage.  However, this time I only was able to run it for 20 minutes.  I suspect that it would have ran longer had I not drained the batteries all day.

So I am going to charge these batteries and try this again.  However, in the meantime I decided to do some theory.  My batteries are 175Ah.   Connecting them in series only increases the voltage -- the  two should be considered one 24V battery.   Amp-Hour is a rating of how long a battery can supply 10Amps in an hour.  To me, this means I should take my wattage, calculate the Amperage, and divide the Ah rating into it.  According to my inverter manual, I should take my wattage, divide it by 10, and divide the Ah rating by that number. At 750 or 650 watts, the manual's method comes to 2.3 or 2.9 hours, respectively.

The amperage draw varies from 5.7 to 6.9. I have read various documents on Ah rating, and I am more confused than when I started. From various sources, I am supposed to divide my Ah rating by the Amperage draw of the device.  The thing about that method is though, I would be looking at 175/7 for 25 hours.  In this case, I expect the manual's calculations (approx 2.5 hours) to be more accurate.  I also checked other batteries out on the web.  US Battery sells a 130Ah battery and calculated that it will run a 25A load for 205 minutes (3.4 hours).   Since my load is approximately 1/4th of that, I should get 820 minutes (13 hours).   I don't believe that I will get anywhere near that amount of runtime.

I also believe that Ah requirement ratings are explained deep in a textbook that takes you  several weeks of studying.  This knowledge has not made it properly to the web, but has been "summarized" by a lot of people that don't understand the subject matter.  To make it worse, battery manufacturers spin these details to make their batteries look better.

Here is what I know.  My device draws 600-750W (or 6-7A) during normal operation.  It needs to run for approximately 5 hours/day over the course of 3 days (15 hours).  In theory, that is 90-105 Amp-Hours, so I don't see why a theoretical 175Ah battery won't provide that charge.

In reality, this power should have been provided using my 12V inverter.  We are dealing with wattages much, much lower than 1000, and my 12V inverter was a 1500W inverter (with 3000W peak).  Now, I believe a single 12V battery is going to have trouble exceeding 2000W, but I am not hitting above 800W.

In this case, there are a couple possibilities.  1) My Cobra 1500W inverter is junk.  2) The #6 AWG wires going to the inverter are a larger impediment than suspected, or 3) My Kill-O-Watt meter is junk.

In any event,  I can run this air conditioner off of 2 12V batteries and 1 inverter.    This summer, I am going to implement the following:

• Install the two batteries ($90ea) in the van in their current setup with the 24V inverter ($190) to run the air conditioner.  Depending on further tests this week, I may add more.
• Solar Panel 185W, 24V solar panel (approx $600)
• Charge controller, 24V (unknown price: $80 - $150)
• Estimated cost: $1,060.

I know that the 2 batteries will power the air conditioner.  I don't know for how long.  I suspect it could be from 2-4 hours.  I will be conducting additional tests (hopefully this week) to figure out how true this is.  All the calculations in the world won't show me what a real life test can do.

Most posts agree that you need about 30% of your operating load to recharge a battery bank in any decent time.  My solar panel is on the lower side of that 30% (30% of 600W = 180W,  30% of 750W = 220W).  However, I will be operating the air conditioner considerably less than 50% of the daylight time.  Also, I hope that once the air conditioner cools down the area of the van, it will drop to fan and be in the 100W range (at which point, the solar panel will power it completely).    I also plan to make use of a fan and install a vent in the roof to let heat escape.

If more power is needed, additional batteries, or even a second solar panel could be added to the system.  I would much  rather start small and improve on it than to go overboard on this system.

Winter update

I thought I'd update everyone with the progress of this experiment.  We are now at the 6-month mark.  I started this on 8/17/2009 and today is 2/19/2010.

Winter has made some things tougher and some things easier. I no longer have to run the generator and air conditioner to keep the van cool.  On the other hand, for the last couple months, the inside of the van has been around 15F-19F in the mornings.

When I start the day, I kick on the space heater for a while.  This gives me a sense of warmth as it heats up the area closest to me.  However, when it's that cold, a 3,000 BTU heater is going to take a long time to get it from below freezing to above freezing.  When it is 40F out, it can actually heat the van from 40F to almost 60F in a 20 minute time span.

Over the last couple weeks, I have taken to starting the van itself up and letting it run while I wait inside work.  I don't completely trust letting the propane heater run by itself without supervision.  Utilizing the gas engine is more expensive, but considerably safer (in my opinion).  The van's heater can warm up the interior well above freezing in under 30 minutes.

In reality though, heating in the morning is almost unnecessary.  If I buckle down and force myself, I can be changed and inside my sleeping bag within a couple minutes.  Within 5-10 minutes, the inside of the sleeping bag become suitably warm.  It can be 19F in the van and 60F inside the sleeping bag around my feet.

As the day progresses, the sun comes out and warms the van considerably.  As peak sun, the van can reach 60F on a sub-freezing day.  If i wake up prior to 3PM, I can enjoy this warm climate.  However, after 4PM, the sun wanes and the van temperature starts dropping down into the 40s.  At this point, the heater is necessary to maintain.

What I should do is go to the gym immediately after work, instead of after sleeping.  However, I find that dealing with putting together a gym bag and other rigmarole in the cold morning to be a nuisance.  Perhaps I'll be able to adjust my patterns before winter ends.  However, in the summer the opposite should occur.  In the summer, going to the gym in the afternoon avoids the heat and ensures that any sweat gained during the hot day is washed off.

Dealing with the cold is easier and cheaper than dealing with heat.  My own body generates lots of heat, which can easily be trapped around me.

Finally, a financial update.  I have updated my equipment page with full details.  For just a quick rundown, I have spend $2,856 on equipment to date.  My operating cost to date has been $890.62.  Looking at just operating costs, I spend $148.43/moth.  A good portion of that operating cost was in fuel between August and December (the cost of traveling).   If you factor out the cost of travel, operating costs drop to $275.70 or $48.45/month.

If you factor in the sunk cost of equipment, the total monthly cost breakdown is $624.44.   Omitting travel costs, my monthly breakdown is $524.45.

A few things are going to happen in the next few months that will add to my costs.  One is that I need to get some exhaust work done.  I have an exhaust leak that is rather loud.  The other thing is that work may request that I take the van with me on my weekends once the weather warms up.  This of course will lead to increased travel and maintenance costs.  I also need to invest in a suitable roof vent.

The final part remains to be seen.  I have ordered a 24V (1500W/3000W peak) power inverter and will be attempting to run my air conditioner off of it using a pair of 12V car batteries in series.  If that can run the air conditioner (which I now believe to be 950W-1010W operating/2020W peak/start-up), then I will attempt to determine the run time and size of battery bank needed to run the air conditioner.  The inverter is close to $200, deep-cycle batteries run close to $100 each, and the cables aren't cheap either.  I would initially charge these using either the generator or power from utility lines.  If all the other ifs work out, I would then look at investing in solar panels on the van roof to charge and maintain the battery bank.

I have not yet factored the cost of the inverter or batteries into my equipment as I may end up not being able to use that type of inverter (some motors require a pure sine wave to operate).  I've also been seeing some 800W, 7000BTU air conditioners on the market (mine is a 9000BTU) for around $300.  These were not readily available when I first started searching out air conditioners.  However, if things work as planned, I could see adding another $1000-$1300 to my equipment costs.

Photos of my setup

UPDATE: Photos are also available on flickr.com/campatwork. 

Bowing down to popular demand, I am posting photos of my camping setup below:

 

The Vehicle itself. 

 Toilet, Bed, Sink, and Desk

Direct view of desk

Winter temperature log

Yesterday (12/28) it was 36F outside and 35F inside at 6:37am.  This is when I turned on the heater.  It heated up rather quickly to 42F inside by 6:44am, but then thermal mass kicked in and started slowing the rate down.  After that, it increased about half a degree every minute till 6:57 it was at 49.3F.  This was with the thermometer approximately 5' from the heater.  At the end, I turned off the heater's fan and moved the thermostat to within a foot of the heater for a minute.  From 6:58 to 6:59, the thermometer went from 49.3F to 52.2F.   I then turned the heater off and after 10 minutes, it dropped to 51.5F.


Today it was somewhat colder out.  At 6:29am, it was 29.5F outside, 28.5F inside.  The van seems to drop slightly colder inside than outside during the night.  I didn't run the heater near as long today.  The rate of increase was rather slow. The biggest jump was between 6:29 and 6:31 - from 29.5 to 32.2.  Then: 6:33 was 33.1 and 6:34 saw 33.5.   By 6:44, it was 38F inside.

So while being directly in front of the heater was warm enough to get changed and such, if the temperatures drop much below 30F, I may have to try running both heaters, or add the van's heater into the mix.  However, once I'm changed and under the sleeping bag, it really doesn't matter too much about the temperature of the van.

Financial updates

12/7/2009 Day 31

Financial Updates

Let me preface this by saying that I didn't really start tracking daily expenses till 9/23.  You should also read my equipment post to see what I am investing in equipment.  Current running total is $2,853.

Since 9/23/2009 (2 months, 14 days) I have put 2,403 miles on the van, using 144.827 gallons of fuel costing me $399.92.  This averages out to 16.59mpg or $0.17/miles. With insurance, comprehensive w/ a $300 deductible is $20.17/month (say $50.43).  $450.35   For the untracked period from 8/17 to 9/23, we'll estimate $200 ($20+), giving us an estimated total of $630.49 -- we'll come back to that number.

I had intended to track the generator usage as well, but have little to go on right now.  The last time I filled it up was 9/28.  I put in 2.2 gallons, costing me $5.68.  I have used it a couple times since then, but still have most of the fuel.  I am pretty sure I won't be using it much at all during the winter.  When Spring comes around, I will give it an oil change start tracking it more.  $456.03

During this time, I also spent $15 for an inspection sticker.  I am behind on an oil change, so that needs to be done soon. While the correct method is to divide that by 12 and come up with $1.25/month, we'll pretend the van won't make it to next inspection and assume the full $15 cost now.  $471.03



Using our estimate for August through September, we'll assume I spent $671.03 on operating costs, along with equipment costs of $2853 (total $3,524).  This gives us an average operating cost of $223.67/month and a total average cost of $1,174.67.

If I had an apartment, it would cost me $500 + utilities.  I would have spent $2000 in rent plus my share of utilities, which used to run me at least $100/month.  At this point, I would have paid out $2400 in rent and utilities.  Assuming these numbers hold up, I save $376.33 each month vs an apartment.  Taking my current total cost of $3,524 and subtracting the $2400 I would have paid, I am left with $1,124 more than the cost of an apartment.   It will take three more months (March) to break even or 8 months since purchasing to fully break even and start truly saving over the cost of an apartment.

However, that's missing a very crucial element.  My operating costs include the cost of transportation.  Based on the first paragraph, I spend approx $180/month on fuel at 16mpg.  My Kia gets 24mpg, which is 33% more efficient.  If I drove the Kia, I would still be spending $120/month on gas on top of the apartment.  So my $376.33 savings each month is actually $496.33.   Four months of apartment + utils + fuel = $2,880.
Remove that from the total van cost of $3,524 and you are left with $644.  At this rate, I should be breaking even by the middle of February and well ahead by March. 

There is a change coming that will make this even more desirable.  Starting this week, I will be parking the van at work and driving the Kia down to it.  Doing so will eliminate most of the fuel costs from the equation, saving  an additional $180/month.  My primary costs at that point will be insurance and propane.  I do plan to start up and move the van somewhat each week to ensure that it is operating properly, so that will eat up some of the fuel in the vehicle.  Plus I plan on doing any other regular maintenance the van needs (like the oil change) -- It needs to remain in fully functional working order.