These products from Solar Converters, Inc take a variable lower voltage, typically a lower voltage battery and increase the voltage to a fixed higher voltage. They also can be adjusted to take a solar panel input.
If you don't see the Solar Converters product you need, please give us a call or send us an email - we can get it for you!
Originally designed to operate pumps at a fixed voltage as the battery discharges, they are also used to maintain a constant voltage on electronics sensitive to voltage fluctuations as well as a means of charging a higher voltage battery from a lower voltage battery or solar panel with MPPT.