# Convert 48V battery bank to 12V for boat appliances - Is this inefficient?

I need a 48V bank for an electric motor on my boat. I also need 12V for my appliances. Obviously keeping both a 48V and 12V bank would be most efficient but the space required and cost of maintaining 2 banks is a bit much. So I was thinking of using a 48V DC to DC convertor to convert a 48V bank to 12V for my boat appliances(lights, pumps, etc.)

http://pt.mouser.com/ProductDetail/Murata-Power-Solutions/HPQ-12-25-D48N-C/?qs=sGAEpiMZZMtwaiKVUtQsNaluUzA10QGezHFBNv8sYMI%3d

But how much would I lose in terms of efficiency? Would the losses be too great?

Would the bank of 4 x 12V 100AH batteries connected in series give me roughly 4800W ( 4 x 12 x 100 = 4800) or 16 hours of 300W use when drawing only 12V after the conversion? Or would the available AH be much less due to the losses from the conversion?

http://pt.mouser.com/ProductDetail/Murata-Power-Solutions/HPQ-12-25-D48N-C/?qs=sGAEpiMZZMtwaiKVUtQsNaluUzA10QGezHFBNv8sYMI%3d

But how much would I lose in terms of efficiency? Would the losses be too great?

Would the bank of 4 x 12V 100AH batteries connected in series give me roughly 4800W ( 4 x 12 x 100 = 4800) or 16 hours of 300W use when drawing only 12V after the conversion? Or would the available AH be much less due to the losses from the conversion?

active| newest | oldestHow are you charging the bank? Is this motor the primary propulsion on the vesle?

1KW bank of solar panels is the main charging for the bank. As explained by Steveastrouk, batteries need to remain fairly uniform in their charge so tapping one would severely affect the longevity of the bank.