Electrical

No one really wants just practical gifts, so weve tried to locate a few items that go beyond pure utility for this holiday season.

Keeping batteries fully charged is a science that cruisers have to master sooner or later. If todays high-capacity AGM batteries arent managed properly, valuable amp hours in can permanently trickle away through sulfation, as we saw in our test of AGM batteries (See Fighting Sulfation in AGMs, PS May 2015). Good battery management means complete re-charging that matches the charging profile of your battery, and this means an accurate sensing of battery voltage. As we saw in our recent report on battery monitors (see Best Battery Monitor Test Update, PS October 2017) a good monitor will also keep track of temperature, as this can be a limiting factor in charge acceptance rate.

Our test focused primarily on the small-wire connections tensile strength, with and without solder, but we also looked at their durability under tough environmental conditions. We tested the pull-out strength without solder and the pull-out strength of soldered connections at 400 degrees by heating the connections in an oven to simulate overheating conditions. We tested fatigue by spinning a 6-inch length of splice wire at 650 RPM in a simple device that we called the wire-fatigue whirligig. Finally, testers soaked all samples for four months in salt water to accelerate corrosion, and then, we repeated the fatigue test.

Two recent tests graphically demonstrated the importance of monitoring state of charge in a boats batteries. hese tests demonstrated that a sealed batterys capacity will be reduced over time, if its never brought back up to a full state of charge. But just how accurate are the monitors we use to gauge our batteries states of charge?

Our test gear comprised a ProMariner ProNautic 12-40P battery charger; West Marine-branded, flooded-cell, deep-cycle battery with a 75-amp hour rating; and two 120-volt, 70-watt incandescent light bulbs powered through a Heart 140-watt DC to AC inverter. This setup created a 12-amp DC load on the battery. We confirmed voltage and current draw using a Fluke Model 867B graphical meter and a Blue Sea Systems Model 8110-amp clamp/multimeter.

In our recent test of absorbed glass mat (AGM) batteries, we cycled five different batteries through 30 deep cycles to 11.7 volts but only partially recharged them for one hour after each discharge cycle at a charge rate of 46 percent of battery amp-hour capacity. (See PS May 2015 online.) The object of the exercise was to demonstrate just how quickly sulfation, which is caused by keeping a battery in a partial state charge (PSOC), can reduce the capacity and eventually permanently ruin a good battery.

Our May 2015 report on absorbed glass mat (AGM) batteries got us thinking about wet cell-batteries. While it is easy to find distilled water suitable for topping off the battery electrolyte in the U.S., what happens when we are not near a reliable supply? Are there any substitutes? What should we avoid?

I just received the latest Waypoints e-letter about gel batteries, where you state they must be charged at no more than about 14.1 volts. We do not use gel batteries in our boat, but do in our camper van. As I understand, Trojan deep-cycle gels can be charged up to 14.4 volts and East Penn marine gel batteries up to 14.6 volts, so why are you recommending the lower voltage?

Sixteen years ago, contributing writers Joe and Lee Minick equipped their Mason 43, Southern Cross, with a Heart Interface Freedom 20 charger/inverter and a Link 2000R from Cruising Equipment, both made by companies based in Valley Forge, Penn. When both of these units were ruined during a knockdown (see PS, April 2013 online), they were forced to look for a replacement.

Editors note: Designing, installing, and wiring a new main circuit panel on a full-fledged cruising boat is an extremely challenging refit project. The writer is a professional engineer who made sure that his installation met or exceeded American Boat and Yacht Council Standard E-11. Failure to adhere to the standard could result in fire, injury, or death. We offer the following article, which outlines the steps involved in constructing a custom panel, as a rough guide. In our opinion, such a project should not be carried out without the consultation of an ABYC-certified electrician.