Installing an electric anchor windlass has its challenged and specific installation requirements. One is the whole question of powering it ip. Given that the anchor windlass is forward and the battery power supply is aft, the electrical supply cable is long. With the combination of high current loads and cable length it is subject to voltage drop problems if incorrectly sized. Windlass performance and therefore lifting capability is reduced by the installation of incorrectly sized and rated cables. The windlass cables should be installed following the most direct route to the engine starting battery, and protected by a properly rated isolator and fuse or circuit breaker protection. Voltage drop should not exceed 5% and ideally be sized at 3%. Typical working current loading's are in the range of 55 amps at no load, 110 amps at half load, and 180 amps full rated load, but that varies with the windlass size of course.
I am frequently asked about the practice or my opinion of installing a separate battery forward adjacent to the windlass, as a means of reducing the heavy battery requirement. and I do not recommend it. While this is one more battery to maintain and also a lot of extra weight forward where you don’t want it, it also still requires charging. So that means you have the extra weight up forward, along with chain and windlass, but you also need a good sized cable to charge the battery with. This means that a cable at least 30-40% of the anchor windlass motor cable would need to be run to also compensate for the voltage drops, so the real advantages are negated. The engine starting battery should be used as it has a high cranking amp (CCA) rating and is more capable of delivering the currents required by a windlass at maximum loads. Before you start telling me “what about running down the start battery” the fact is you should be running your engine and motoring when retrieving and anchor. What happens is that the engine alternator takes most of the windlass load when underway and motoring up on the anchor when heaving.
Many windlasses have DC starter motors, and some now use permanent magnet motors, typically in the range 600-1000 watts which simplifies construction and reduces weight and size. They do cost more but they use a lot less power and do not need the maintenance. It is important to maintain windlass DC motors if you do a lot of anchoring, as brushes wear, commutators wear and performance suffers. If you do a lot of cruising and anchoring then think about a service or inspection every 12-18 months. Check out DC motor information here. More electric anchor windlass information and anchor handling advice.