This installation requires some electrical skills and since errors could cause an electrical fire you should not attempt it unless you feel confident. This project has not been checked for compliance with ABYC or USCG standards and the author presents this as a guideline to be interpreted by qualified installers. No warranty or guarantee is given or implied.
THE THEORY BEHIND THIS PROJECT
Winches and bow thrusters, located in the bow, are usually a long distance from the starting or house batteries. These items draw a heavy current for a short period of time. Unless you use very heavy cable for the long run, the voltage drop by the time it gets to the device, will have reduced the available power.
What is worse, however, is that very heavy copper cable is an invitation for an on-board fire if it gets shorted so for safety you have to add a large fuse - large enough to take the stalled motor load of the winch without giving you a nuisance blow - yet small enough that a short at the far end can draw enough current through that long cable to blow the fuse.
PROVIDING A REMOTE BATTERY IS SAFER, CHEAPER AND WORKS BETTER
- Automotive battery with enough capacity to run the device for the longest job. (Multiply AVERAGE current by time in hours to get amp-hours required, then double this figure. Example, 80 amps x 30/60 hours x 2 = 80AH ) For charging compatibility it should be the same type (lead-acid or gel) as the starting battery.
- 50 amp combiner The combiner should be mounted with the remote battery.
- Two fuses or circuit breakers. I prefer the automatic reset thermal breakers that are typical in the automotive industry.
- A good quality battery box.
- Red and Black cables for the charging line - 10 gauge is adequate.
- Conduit to protect charging line - essential on a metal boat, desirable on others.
Provide a SOLID mounting for the battery and battery box. Keep in mind that the bow takes much more of a pounding than the traditional battery locations so go overboard (not literally) on strengthening the mounting. The battery (box) must be rock solid when strapped down. Due to the motion and stresses, I would not use the conventional webbing strap they supply as the buckles provided are usually poor. Good quality ratcheting strap(s) of a material that is acid proof would be better, or provide a stainless retainer with through bolts and wing nuts.
Connect the device to the battery following manufacturer's suggestions. Connect the charging line, following this schematic and the installation instructions supplied with the combiner. If you use our thermal circuit breakers, you must use crimp on ring terminals to connect the wire - the screws are too small to adequately secure 10 gauge stranded wire, even if tinned.