The “service entrance” (pictured in previous article) was located 6 feet from the northwest corner of the building, to place it underneath the first short flight of steps and landing. I had chosen to house the battery bank and peripheral equipment (to be detailed with photos in a future article) under the stairs because of limited space in this small building. This action did not conform to code, it did not allow ample room or access to the hardware. The biggest detriment was the fact that the stair treads must be removed to inspect and water the batteries. Very cumbersome. When the main house is built, I will include a “power room”.
I installed a reducer at the building end of the underground pipe, to convert the 6 inch pipe to 2 ½ inch. The smaller pipe rose about 2 feet above ground, to enter the building. The joint between pipe and wall was caulked.
The 1/0 (one ought) power lines were connected to a junction block. #6 wire was used for the short run from the junction block to a disconnect, from the disconnect to the C-30, then finally to the battery bank. I had decided to use a combination of batteries for head-to-head testing purposes. This is highly NOT recommended! Lower performance and battery life will result. In spite of this knowledge, I am known to conduct some unorthodox experiments. I used four Optima yellow top and four Deka marine 12 volt deep cycle batteries, all wired in parallel to maintain 12 volts and multiply storage amp/hours. The Optima’s contain gel electrolyte, the Deka’s flooded lead acid. These should not be used together, but I wanted to compare them. The main reason not to combine them is that they have different charging requirements. The best charge voltage for one type is not best for the other type. As a result, one type will suffer and not yield a full lifetime. As a compromise, I set the field adjustable bulk and float charge voltages as follows: bulk voltage - 14.4 volts, float voltage - 13.3. These voltages match the requirements for the lead acid batteries, but are not ideal for the gel cells. Even though my test was lacking some accuracy, the results were not unexpected. With 8 years of use, the lead acid batteries had to be replaced at 4 year intervals. The gel cell batteries were replaced at the end of the 8 year cycle, yielding twice the life of the lead acid type. At twice the initial cost, the gel cells lasted twice as long. The other main factors were that the gel cells did not have quite as many amp/hours of storage capacity, nor did they receive optimum charge voltages. On the plus side, they did not require watering. The final conclusion was that either type would do a fine job, and at a comparable cost.
Large industrial batteries are available, and well suited, to this application. However, they come with two huge disadvantages. One, they are very heavy and require machinery (a forklift) to handle them, and shipping costs are high. Two, they represent a large initial expense. But, when you consider that they will last for up to twenty years, they can be very cost effective in some situations.
Power was then run to a conventional Square D breaker box, whose breakers were d/c rated. This would be the “12 volt” or “d/c” breaker box. I wanted to utilize d/c throughout the building as much as possible, since d/c is more efficient than a/c, especially for loads having long run times. The Novacool refrigerator and all lighting would be d/c powered.
From this breaker box, the building was wired with 12 volt d/c using standard 12/2 wire, as opposed to conventional 14/2, to minimize line loss. Standard switches and outlets were placed throughout the building.
We have power to spare in the summer months, but in winter need to save all the power we can to avoid generator use. What we can not avoid is to reuse and recycle any and everything when possible.
All photos by Jeff & Kathy Chaney
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