It's mid-November now. Thanksgiving is next week, and December is right around the corner. Soon it will be Christmas, then New Year's Eve when I will drink a toast to 2015, the start of a new chapter in my life, for
I'm retiring from the software industry at the end of this year.
Retirement will bring big changes to my life, so it's a very interesting time for me. I've been doing a lot of thinking these past few months about what next year may bring, and over the weekend I made some final decisions that will impact my life in the tent, the most important of which is the concession that...
I'm gonna need electricity.
Yep, that's right, I have to bring in electricity. I'm actually okay with this decision, finally, but I must admit that I didn't like going down that road to begin with. Electricity is just too...tempting. Once I have an AC outlet in my tent, I'll be tempted by other things, like televisions and DVD players and...God, help me! So I'm about to begin my battle with worldly temptations again, and I hope I have the strength to persevere.
In any case, for better or for worse, I've decided to flirt with that temptress in order to pursue my passions next year. I plan to write and make music for hours at a time, so I'm gonna need to plug-in.
I'll use a laptop for writing. I'm still shopping for one, but it will be very basic. Just a small system with Internet capabilities. Small, cheap, and low power consumption. For music, I plan to do a lot of recording and to rehearse once in a while for live performances. I already own an eight-track digital recorder, and a small acoustic amplifier for live performances.
I plan to build a 12V system with a single AC inverter. To correctly size the components, I need to look closely at my consumption.
First, I need to determine the peak load by adding up the wattage of all devices that could be running at the same time. This sum will determine the inverter size that I'll need.
The devices that I'll be operating are:
- Laptop = 100W
- Digital recorder = 20W
- Small acoustic amplifier = 150W
I might actually want to operate all of these at the same time. For example, I might want to mic the amplifier and record the output, then download the recorded tracks to the laptop. So my peak load could be as high as 100 + 20 + 150 = 270W. I'll round that up to a 400W inverter which I can easily find for under $30.00.
Next, I need to find my average daily consumption by multiplying the wattage of each device by its average run-time. That will give me my average watt-hours per day. But what will my "average day" look like? Hmm. Well, some days I may write all day long, so a day of writing would cost me 100W x 8 hours = 800 watt-hours. Other days, I might be recording all day long, so 20W x 8 hours = 160 watt-hours. I don't plan to do much rehearsing through the amplifier, so maybe a few hours here and there would be a big day for that, something like 150W x 2 hours = 300 watt-hours per week at the most.
Ok, that helps, but it still doesn't give me a good sense of what an "average day" might be like, so let's explore that. The writing days are the heavy consumers, but if I'm really writing all day long, then I'll probably want to get out anyway, maybe go to a coffee shop and socialize a bit and get on the Internet. So I'll just budget for one day of at-home writing per week. Now, for the digital recording. My recording time will probably go in spurts. I might record for a few days in a row, then take an entire week off. So on average, I'll budget for two full days of recording per week. So that gives me: (800 x 1 day) + (160 x 2 days) = 1120 watt-hours per week. I'll round that up to 1300 watt-hours per week.
Now that I know my average consumption, I can start to think about how many days I'd like to run before having to recharge. At the moment, I plan to recharge my batteries at a local auto parts store (I'm still looking into that, so I'll have another post on recharging later). I don't mind taking batteries in once a week for recharge, but I'd like at least five full days of continuous operation on a single charge. And I don't want to draw the batteries down below 50% depth of discharge, so I'll double the weekly consumption rate to 2600 watt-hours and size the batteries based on that figure.
For a 12V system, I'll need 2600 watt-hours / 12V = 217 amp-hours per week. I can get that from just one battery, albeit a pretty expensive one (something like the
Trojan J185H-AC 12V 225AH flooded deep-cycle battery, which costs over $300.00!). Or I could build a battery bank from 12V or 6V batteries.
So the problem now comes down to acquiring the batteries and figuring out how to recharge them. I'll need to do more research to figure that out, so stay tuned!