Camping At Work: Low Voltage Beep

Tuesday, May 25, 2010

Low Voltage Beep

I ran the air conditioner for a short while yesterday, along with most of today. Around 3:30pm, I got a low voltage warning from the inverter. The voltage reading on the inverter was at 20V (vs 25V where it starts at).

For 5/24, I ran the air conditioner for 46minutes and pulled 0.41Kwh. For today, I ran it 5hrs, 40 minutes and pulled 1.74Kwh before I got the beep. That totals to 6hrs, 26minutes of run time and 2.15KWhrs. In my last post, I had estimated my battery bank of being capable of 8.4Kwhrs (Each battery being a 2.1KWhr battery, times 4 batteries). So I seem to be getting about the run time of one battery instead of 4 (or even 2).

Now, to be 100% fair.. once I turned off the air conditioner, I continued to run the fan for another 1.5 hours. Granted, the power usage of the fan is less than the output of the solar panel, so it could potentially run indefinitely.

Given the current setup, I definitely will not be able to use the air conditioner for 3 days on one charge. At this point, I'm not exactly sure why I'm only getting 25% of my capacity out of the system. Perhaps I need to redo the wiring inside the battery box to more evenly draw across all 4 batteries.

As a stopgag, I can try a few other options. The easiest would be to bring the generator back down and only run it once the batteries have ran out. I also have a 24V charger, so I could be charging the batteries off the generator at the same time. I could also upgrade my battery array to 6 or 8 batteries.

Another option I've been considering is one of the evaporative/swamp coolers. Generally, these are a fan that blows over water. They work on two concepts: 1) water has thermal mass and stays cooler longer, and 2) small drops of water will cool you down and then evaporate away. They have a few downsides: 1) they don't actually cool the air, just make you feel cooler, and 2) they increase the humidity. If you let them run long enough in an enclosed space, the humidity increases and the cooling effect stops. Also, if the humidity is too high, sweat stops evaporating and you warm up either further. Another disadvantage is that you have to refill the water from time to time.

Back to the drawing board..

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About

I keep track of my equipment costs here.

Photos are here.

I work about 117 miles from where I live. My work schedule is fairly interesting. I work night's – 12 hour shifts. It alternates between 3 and 4 shifts each week. Factoring in a 1 hour lunch break, I work 33 and 44 hours. I then end up with really long weekends. The drive takes 2 hours and 15 minutes each way, so on a 12 hour shift, a round-trip is 16.5 hours. That leaves 7.5 hours to sleep, hygiene, and eat. For the last two years, I have been either renting an apartment or staying on a coworker's couch for the 2-3 days (and it is daytime that I sleep) that I'm at work. Rent in the DC area for a single bedroom apartment is very comparable to my mortgage payment on a 5 bedroom house at home.

For a permanent solution, I have decided to use a conversion van as my apartment during the work week and hope to sleep in the work parking lot during the day. I checked with the both the county sheriff's office and the county attorney's office. While there are rules against sleeping on a public sidewalk or park during the night (which might apply to someone inside a van) there are no issues with me sleeping at those same places during the day. Private parking lots require permission of the owner, otherwise I could wake up with a $100 fine on the van. The sheriff's office advised me that I should be prepared to be woken up a few times if someone called in a suspicious vehicle. Otherwise, there are no legal issues with me camping out in the area on a semi-regular basis.

My quest for cheap living begins.