Now, as for keeping the battery charged each day I have 2 solar panels as mentioned above. They total only about 30 watts, or 2Amps, of power at peak sunlight (which is only between 10am and 4pm at this time of the year). For 6 hours per day I can re-capture about 12Amps of power used from the previous day. The other 7 hours of sunlight are roughly half power capture for another 7Amps. All together, I can recapture roughly 19Amp hours of power back into the batteries that I may have used the previous day, or are using today.
I recently upgraded my solar panels to a total of 75 watts of charge capability (Five 15w panels), roughly 5 Amps per hour at peak light. I have decided, for now, to leave two mounted on top of the van, but to leave the other 3 unmounted to direct South for optimal direction and angle. So, with summer giving me 6 full hours of peak light, plus another 7 hours of non-peak I can recharge (6h*5A=30AH + 7h*2.5A=15AH) 45AH per day. That is double what I was getting before and nearly an entire battery cycle with the single battery I am currently using.
My normal daily use would be a few hours of laptop at a cost of roughly 23 Amp hours. Now with some headroom in the solar area, I can operate my fridge when needed at an additional cost of 0.7 Amp-per-hour (16.8 Amps per 24 hours). Add that to what I already use for a total of 50 Amp hours used per day… still no fridge unless I can cut back on my laptop time.
I also added a simple charge-control-center to give me easy expansion as well as a very flexible use of my solar and battery power.
A couple things I am currently doing to help;
- Buy a set of clip on LED lights and use them instead of interior trailer lights
- Buy a rechargeable LED flashlight and use it instead of interior trailer lights
- Use the laptop battery while working, and only use the trailer power to charge the laptop when powered off. Charging only is 20watts but using the laptop while it charges consumes 60 watts. Use it, power it off, then recharge it.
- Avoid foods that require refrigeration. Find; Canned meats instead of fresh or packaged, mustard and catchup packets over jars, dry milk instead of fresh… My fridge uses 3.5Amps when used. Luckily, it powers on only 1 of every 5 minutes so uses 0.7Amps per hour (still too much just to keep my mustard cool)
- Get my solar panels facing the proper direction (South). My 30 watt panel is mounted on top of the trailer facing straight up. The sun does not get to it until 10am and stops hitting it by 4pm. If I remount it to face South, as opposed to Up, I could capture another 9-10Amps each day (about 25% more daily).
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download: Battery Amp Hour and Solar charge calculator (24.57KB) added: 13/06/2011 clicks: 107 description: An excel spreadsheet that I developed to help me determine my battery usage and potential solar re-charge while living 'off the grid' in my camping adventures. |
