When I come onto a boat to update the batteries and charging system I often find wiring that has been done previously that is unfused. Many projects like adding ACR’s (automatic charging relays) have been done without putting a fuse on each wire that leaves a battery and connects to the ACR.
The same is surprisingly true of battery charger wires, wires to battery isolators, and alternators that are no logher wired to the starter motor.
Every time a wire is connected to a DC source, either at a buss bar or battery post, that wire needs its own fuse that is sized for that wire.
Often what I charge for completing a project can be 60-70% made up of the cost of adding, and wiring in the appropriate style fuses that were missing from systems that might look pretty good at first glance.
Buss bars are another upgrade that is often needed to make a DC system safe. Too many wires on a single battery post (more than 3) are non-compliant with safety standards and prone to coming loose.
Finally the layout of the buss bars and new fuses are going to need space to be mounted in a way that they are serviceable. When I make any changes to a system, like rewiring batteries, or adding a solar charger, I must upgrade the wiring to a point that I at least know each wire is protected with a fuse or breaker.
That often turns what seemed like a simple project into a little more extensive rewire. But it is always worth the effort. When finished the boats DC system will be safe and reliable, not requiring any owner attention for many years.
The alternator has been connected to the house bank with a heavy cable. -Okay (Hopefully it is fused on the battery side.)
Original wire from alternator to starter and start battery not removed. (House and start battery are now permanently connected with a small unfused wire.)
Internal regulation is still in place after connecting the alternator to a large house battery bank. (The alternator is likely to be damaged by overheating the next time the house bank is deeply discharged.)
It’s been a good year making electrical repairs and upgrading yacht electrical systems. With all the excitement over new lithium battery technology, and new more powerful solar charging, it is important to make sure your current system is working optimally before deciding to make big changes.
Just this year I have tested and repaired four boats that were suffering from failing alternators. The original call was for me to come and give an estimate to add solar to the boat, and give advice on possibly upgrading to lithium batteries.. When evaluating a boat I look at the whole system of charging and storage, not just at solar or batteries as a stand alone project. In many cases the batteries were good, but the alternator had failed some time ago, but not completely, so the failure was not obvious. The owner had a general feeling that their battery system was no longer keeping up with demands the way they would like and knew something needed to be done.
In all but one case the alternator needed to be upgraded to external regulation as part of the repair to prevent future overheating, and damage from changing a large battery bank. The lesson is: It’s still important to check the basics before moving forward with new solutions.