This may be a bit off-topic. I have an older solar power system, which uses four very large 6v deep-cycle batteries connected in series for its battery bank. It's trouble free and works perfectly, except, because it's older technology, the integrated inverter puts out a type of AC power that my (ISP provided) DSL modem will not operate on. So, to use the modem I have a small Coleman inverter, which I power from a separate automotive battery. Can I safely tap off 12v power from two of the 6v batteries in the solar system without disturbing the battery bank setup??? If so, will I need any additional circuitry, such as diodes in the system??