Simple electrical upgrade Page 3 - Sail Magazine

Simple electrical upgrade Page 3

Our 1973 Norlin 34 project boat had been used mainly for club racing in its latter years, and it showed. Among its many outdated systems was the battery-management setup. It was no worse than what I suspect can be found on many other boats of that vintage, but it would not suffice for extended cruising.The two Group 27 90AH deep-cycle lead-acid batteries, one for house
Author:
Publish date:
engine_block_negative_cables
battery_monitor_shunt

The project

On older, skinnier boats, it can be difficult to find room even for something as small as a battery. You want to keep cable runs between alternator and battery as short as possible to avoid voltage drop, and locate the battery where it can be secured firmly against movement. A battery box that will contain acid spills and also protect the terminals against a possible short circuit is a sound investment. In order to avoid an overlong cable run from battery to switch, I had to sacrifice a bit of valuable stowage space and locate the starter battery alongside the quarterberth.

There was nothing worth keeping, so I started the project by removing the old batteries, cables, and switches. I consulted a voltage-drop table and found that for my installation, with an 80-amp alternator and a maximum cable run of just over 6 feet, AWG 4 battery cable would be more than adequate. I calculated that I would need 21 feet each of positive and negative cable, and some of the prices quoted for marine-grade tinned-wire cable made my eyes water. I ordered the cable, terminals, heat-shrink covering, and a crimping tool from Genuinedealz.com, the online store that offered the best deal at the time.

I suffered momentary brain fade once I had all parts in hand and was ready to begin. What to do first? I decided to complete each aspect of the installation before moving on to the next.

The switch. After connecting the two 90-amp batteries in parallel, I measured, cut, and installed the positive cables from the alternator to the house battery bank, and from there to the battery switch and the domestic panel. Cutting the cables, paring back the insulation, crimping the terminals on, adding protective heat shrink, and wiring up the switch cost me most of an afternoon, a set of skinned knuckles, and several explosions of temper. I re-used the 0 AWG charging cable from alternator to battery, but everything else was new.

The ACR. Next, I mounted the ACR as close as practicable to the batteries, inside the battery compartment. The Blue Sea wiring diagram suggests that the starter battery should be charged first. Nigel Calder’s Boatowner’s Mechanical and Electrical Handbook suggests that the house bank should receive the primary charge, rather than have unregulated charge current running through the smaller starter battery. On a low-capacity system like mine, I doubted it would make any difference. I ran a cable from the starter battery side of the switch to the A terminal of the ACR. From the B terminal, I ran a cable to the house side of the switch. ABYC standards require overcurrent protection in positive DC cables, so I added 100-amp fuses to the cables between the switch and the ACR (Photo 4). Following instructions, I wired up a small LED light to tell me when the batteries were combined.

Negative circuit. It’s a good (and tidy) idea to have a common grounding point near the batteries (Photo 5). I installed a busbar in the battery compartment and took all the DC negatives to it, including the negative return for the ACR. Then I ran a single grounding cable down to the engine block. The AC ground should also be connected to this negative busbar.

Battery monitor. The DMM-1 came with a dual shunt, which is necessary to measure amps instead of just volts. It had to be wired into the negative return from the battery banks where it measures all incoming and outgoing current (Photo 6). Smaller sensing wires had to be run from the shunt to the various battery banks and to the display, which I mounted above the switch panel. The instructions had seemed confusing to me, but it all became clear once I started. The negative cables from the two battery banks went to the central terminal on the shunt; the negative cable from the switch panel went to the right-hand terminal; and the left-hand terminal was connected to the main grounding busbar.

Solar panel. The small Sunsei solar panels sold by West Marine looked like an economical way to keep the batteries trickle-charged. I wired one of the 7.5-watt panels directly to the house bank and took its negative to the common grounding busbar so that the DMM-1 could measure the charging current. It’s topped out at a 0.2 amp charge and has helped keep the batteries in good order during the summer.


How it all worked

Apart from checking the electrolyte level in the house batteries (the cranking battery is sealed), I didn’t have to think about the charging system all summer. Voltage in either battery bank never dropped below 12.6 volts between charges. The ACR, which lets the house bank be charged only after the starter battery reaches full charge, obviously does its job well. All I have to do is turn the switch to “on” when I get to the boat and “off” when I leave—which is exactly what I wanted.

Related

ElanGT5-a

Boat Review: Elan GT5

Aboard many modern yachts, it can be hard to remember exactly what boat you’re on until your eye happens to light upon a logo. However, this is most definitely not the case with the Elan GT5, a performance cruiser with a look all its own and style to burn.Design & ...read more

01-Lead-P1060210

Handheld VHF Radios

For many sailors, cell phones have become their primary means of both ship-to-shore and ship-to-ship communication. Even the Coast Guard will often ask for a cell number after it receives a distress call. None of this, however, makes a VHF radio any less important—and this goes ...read more

Seascape24

Boat Review: Seascape 24

Since its inception in 2008, Slovenian builder Seascape, founded by a pair of Mini Transat sailors, has focused solely on creating boats that are both simple and loads of fun to sail. With their 18-footer and then a 27-footer they succeeded in putting out a pair of trailerable ...read more

01-Trash-Tiki_in-partnership-with-Subtch-Sports_starting

The Adventurers Aboard Trash-Tiki

If you were in Gotland, a popular island vacation destination off the coast of Sweden, on the morning of July 3, your holiday might have been interrupted by a startling sight: a tiny island of trash approaching shore with people aboard. It was, in fact, a sailboat made from ...read more

atlantic-cup-trailer

2018 Atlantic Cup Video Mini-Series

Atlantic Cup 2018: TrailerThis past spring, SAIL magazine was on-hand to document the 2018 Atlantic Cup, a two-week-long Class 40 regatta spanning the U.S. East Coast and one of the toughest events in all of North America. The preview above will give you a taste of the four-video ...read more

hardangerfjord

Cruising: Holland to Norway

In 2015, we cruised to Norway’s Lofoten Islands on our Nordic 40, Juanona, which we’d sailed transatlantic from Maine to England. Our 2016 plan was to cruise through the Netherlands to the Kiel Canal, sail into the Baltic as far as Stockholm, then cruise the western coast of ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell.Got a tip? Send it to sailmail@sailmagazine.comThe Watch-keeper’s Nightmare The commercial watchkeeper’s most awkward decisions come with a vessel converging from abaft the starboard beam showing a red light. If he’s more than 2 points, or around 22 ...read more

cosair760R

Boat Review: Corsair 760R

We’d only been out on Miami’s Biscayne Bay aboard the Corsair 760R a few minutes when Corsair Marine marketing manager Shane Grover and I began bemoaning the fact neither of us had a GPS with us to determine our boatspeed. Moments later, though, we both came to the same ...read more