Sailing Vessel (SV) Sarah
12VDC Electric Upgrades
| Although the major changes to the electrical systems on Sarah are on the AC side to accommodate European power, I still have a number of upgrades to accomplish on the 12VDC systems. |
| Battery Switch |
The battery switch I inherited on Sarah was the conventional single
rotary switch (Battery 2, Both, Battery 1, Off), with all circuits wired to
the output terminal on the switch. This wiring presented the following
limitations/problems:
My solution for these issues is to:
Under normal operation there should be no reason to change the switch settings. Should one of the batteries fail to hold charge it can be switched off, and the remaining battery can supply all functions. |
 Here is the original battery selector switch.
A
quality item, but the way it is wired presents all of the issues described
above. |
 Here is the cable area behind the switch, viewed from in the hanging
locker.
|
 As usual the major problem was removing the old equipment rather than
installing the new.
I
don't know how these wires were attached to the old switch, but it took me
the better part of a morning to get them off. The cable congestion
prevented me from putting a socket on the nuts. So I had to remove the nuts
with a set of needle-nose pliers, turning the nut 1/16 revolution at a
time. The picture was taken by holding the camera in the cable area and
turning it 90 degrees. I could barely see the back of the switch, and not
at all when my hands were in the cable area. Basically had to take it
out
by feel. The cables were not long enough for me to pull the switch off the
bulkhead and remove the cables from inside the cabin. |
 Here are the new switches installed inside the wet locker.
Only
when I had drilled the holes and fitted the switches did I discover that I
could have put the switches in a better orientation. If they had been
rotated 90 degrees that would have put the switch keys in the vertical
position when "ON" or closed. That orientation would have precluded any
loose item in the locker from falling on the handle and turning the switch
to the "OFF" position. The keys are removed when the switch is in the "OFF"
position. I believe it still would be difficult for anything in the locker
to move the switch, so for now they will stay as fitted. Of course it is
possible, so it is almost 100% that it will happen sometime.The reason I oriented the switches in this manner was to maximize the distance between the terminals on adjacent switches - to prevent contact between the circuits on two switches. The loose red cable is for the LectraSan sewage treatment system and was connected to the COMMON terminal on the old switch. This cable is now connected to the START switch so the Start Battery will be used to supply the high current demand of this unit. Previously turning on the LectraSan would cause the autopilot to go bonkers. The large orange cable running across the from of the locker is the Starter/Alternator Output cable from the engine compartment. This cable is connected to a Battery side of the START switch so that the alternator will always charge the START battery. A Battery Combiner will be added to electronically connect the batteries during the charge process and provide a charging current for the House Battery.. |
 The switches are labeled (from left to right)
START, HOUSE, and BOTH.
Notice
that the BOTH switch is in the open position. This is the normal position
to isolate the starter circuit from the house circuits. If the I need to
use the HOUSE battery to start the engine, I would open the START switch
(disconnecting that battery) and close the BOTH switch. That would connect
the starter circuit to the HOUSE battery, while it continues to supply
current the house circuits. Similarly I can use the START battery for the
house circuits by opening the HOUSE switch and closing the BOTH switch. I
would only combine both batteries (by closing all switches) if I were trying
to start the engine and both batteries are badly discharged.The switch keys are secured to the switch bases with wire fishing leader.
|
| Battery Combiner |
| In the picture above, the black box to the right of the switches is the Battery Combiner. The red cables connected it to each of the battery-side terminals on the START and HOUSE switches. When the alternator begins to charge the START battery this switch will be open send the full output of the alternator to the START battery. Once that battery reaches 13.3 VDC the switch will close connecting the positive terminals of the two batteries together. At that point the alternator output is shared by both batteries. When the engine is shut down and the charging current ceases (reducing the START battery to less than 13.3V) the switch will open isolating the two batteries. |
The battery combiner worked flawlessly for
over a year. Then after spending the winter in Cascais, PT I discovered it
had failed on our way from Cascais to Gibraltar. I'm not sure when the unit
failed or what caused the failure. I purchased the West Marine Combiner
based on the charging current that would have to be supported. The max
output from my alternator is about 45A and the max output from my battery
charger is 40A.
 Specs
on the combiner said it should easily handle these currents. What I believe
might have happen is when my batteries failed over that winter (see below)
the START battery was no longer capable of providing the current required by
the starter motor. When I started the engine dockside with the battery
charger on, the batteries were combined and the starter motor current was
supplied by both batteries with the current from the HOUSE battery coming
through the combiner. This current likely exceeded the capacity of the
combiner and caused it to fail.
While in Gibraltar I ordered a heavier duty replacement, the Blue Seas 7600 and had it sent to my brother who would join me a few weeks later in Almerimar. This combiner is rated for 60A continuous duty and 120A for up to 2 minutes. At the time I had not completed my analysis of the failure, and just bought what I thought was the heaviest duty combiner in the West Marine catalogue. By the time my brother arrived with the new combiner, I realized that this unit may not be robust enough to handle the starter load should the current batteries also fail. I decided to put off the combiner installation until I was in my winter berth in Lagos, PT and could determine if it was sufficient for my installation. Shortly after arriving in Lagos I did install the new combiner (picture above). The intention was never to have the combiner sustain the starter motor load from the HOUSE battery, the BOTH switch was intended for that purpose. The problem was how to prevent that load coming onto the combiner should the batteries fail again. For that purpose I have ordered a switch for this combiner to allow me to turn it off when connected to shore power. I will bring that switch back from my visit the states in November, 2006. In the meantime the combiner should have no problems as long as the batteries are in good operation. Another precaution is to always disconnect from shore power (or turn off the battery charger) a minute or so before attempting to start the engine. That should allow the START battery voltage to drop below 13.3VDC and cause the combiner switch to open. If I have a weak START battery I can use the mechanical switches to use the HOUSE battery to start the engine, or combine them. In either case the additional current from the HOUSE battery will not go through the combiner switch. Blue Seas does sell a combiner that is rated for starting current loads, but I have stayed with this combiner for several years and as of 2008 I have not installed the switch to manually turn the combiner off. |
 The
drawing on the right is a schematic of the battery and charging circuits on
Sarah, showing the three battery circuit switches (HOUSE, START, and BOTH)
and the battery combiner switch.Also shown are the four main load circuits connected to the batteries.
You can view a full-sized image of the schematic by clicking on the thumbnail, above. |
| Battery and Battery Box Failure | |
 While
sailing across the Atlantic from Florida to Portugal I discovered that the
bottom of the outboard battery box had broken loose, the battery had dropped
several inches and was resting on the inside of the hull. I discovered this
problem while Sarah was moored at Capt. Smoke's Marina in St. Georges,
Bermuda and we were in final preparations for our departure for the Azores.
We had already spent a week in St. Georges getting the stern rail fixed and
I was not anxious for a prolonged stay in Bermuda to repair the battery box.Although the built-in box had failed, the battery was still secured in the plastic case. There was little or no chance of the electrolyte spilling. Although the battery had dropped down several inches and was at a slight incline it would not move and I felt there was no threat of producing abrasion or an impact load on the hull. Therefore I elected to depart for the Azores with the battery box in this condition, and we completed the cruise to Cascais, Portugal with no issues from this situation.
|
|
 The
picture on the top right shows the battery box after I removed the battery.
The bottom of the box has broken free of the walls and dropped onto the
hull. The picture below shows the forward end of the box where the bottom
has dropped about one inch lower than the aft end of the box. This incline
was due to the shape of the hull under the box. |
|
 Although
we sailed to Portugal without any further issues from the battery
installation, I did manage to kill at least one of the batteries once we
reached Cascais. I had purchased new Rolls Batteries while in Florida.
These are their new modular batteries with removable cells. The pictures on
the right show the START battery after I removed it to repair the broken
battery box. |
|
A battery charger is inherently slower to re-charge a battery than the engine alternator, as the charger is designed primarily for shore side operation where the boat may be left on shore power for a week, a month or longer. However the fuel savings by using the generator rather than the engine (as well as the reduced engine wear) more than made up for the slower charge rate. Still I wanted to reduce the amount of generator run time as much as possible. Because I didn't have the optional temperature sensor, the installation manual recommended that I set the temperature switch on the charger to "Hot". The other settings are "Warm" and "Cold". The charger delivers maximum current to a cold battery and minimum current to a hot battery. Therefore the "Hot" setting (without a sensor) is the "safe" setting to prevent battery damage. Since we were running the charger for relatively short periods I reasoned that the temperature of the battery was not a significant issue and while we were sailing to the Azores I changed the switch from "Hot" to "Cold". This delivered a much higher charge current to the batteries and reduced the generator run time significantly. Unfortunately I immediately forgot about this switch setting for the rest of the voyage and left it on "Cold" even when we were tied to a marina dock running on shore power. This probably did no major damage while we were in the Azores, but when we arrived in Cascais I put Sarah on continuous shore power for several months. I was on board for the entire month of September, then I returned to the states for the month of October. All this time the charger was pumping current into what it thought were "Cold" batteries, but in fact it was boiling the electrolyte in some very hot batteries. Shortly after I returned to Sarah in November I noticed that even with the battery charger on, the HOUSE battery was showing low voltage. I checked the battery and found no visible electrolyte in any of the cells. The START battery also appeared dry. Then I remembered the temperature switch and moved it back to the safe "Hot" setting. Rolls Batteries have a deserved reputation for taking abuse and repeated discharge, but no battery is designed to be run dry of electrolyte. Hoping I might have dodged a bullet I refilled both batteries with distilled water. They both returned to a full charge, but the house battery would not hold its charge for more than a few hours under any load. The start battery was able to support a small load (normal cabin lighting) for a 24 hour period, and although damaged seemed capable of fulfilling its role of providing sufficient current to start the main engine. So before I resume cruising I must replace at least the HOUSE battery. While the battery box was being repaired I removed the batteries and tested each cell. Because of the modular construction of the Rolls Battery i was able to select the strongest cells for the START battery. |
|
Repairing the battery box looked like a difficult and messy
job. Fortunately there was crew from Poland working on a 55' catamaran at
our dock in Cascais at the time.
 One
of the crew was an expert with fiberglass and offered to repair the box for
me. An offer I immediately accepted. On the right is the repair to the
box.
He first ground down the inside of the box to set it up for the glass work, and removed the old bottom. Then he glassed in some cleat stock to provide the support for the new bottom. Finally he glassed in the new bottom. He wanted to gel coat the inside of the box to make it look professional. I declined as it would make me want to finish off the other box as well. Everything looks good. In the picture the glass is still setting up. In a few days I will put the battery back in the box. Right now I'm agonizing over whether to replace both batteries or just one and use the current 12 cells to come up with the best 6 cells for the other battery. Rolls Batteries are very expensive in the states. In Europe they are outrageously expensive. Also there is no Rolls dealer in Portugal, so I will have to pay shipping from the UK. I tried to find a good source of deep cycle batteries here in the Lisboa area, but no one seems to offer batteries in the class of Rolls or Trojan. Eventually I replaced both batteries 4D batteries from Tudor, a European manufacturer. The batteries lasted all summer in the Med and on the sail back to the USA in 2007. They are still working fine in 2008. |
|
| Additional Breaker Panel | |
 Sarah
has the original Marinetics electrical panel installed when the boat was
built by Pearson. This is a large panel with one column of 120VAC breakers
(yellow) and two columns of 12VDC breakers (Red and White). When I
purchased the boat the previous owner had already overrun the number of
circuit breakers and had multiple circuits on many breakers. I consolidated
several of those circuits and reduced the number of circuits on several of
the breakers, but overtime I have added a number of circuits and those had
to go on one of the existing breakers.Finally in the fall of 2006 I had to do something. I wanted to add a few more circuits and I wanted to isolate a few existing, but all of the existing breakers were in use. For a number of years I've had a Blue Seas 12VDC Breaker Panel in my parts bin for just this purpose, but I've never gotten around to installing it. Now was the time. The previous owner had installed a stereo speaker on the electrical panel, which I removed shortly after purchasing Sarah. That left a large round hole in the panel (picture on the left), which for years I covered with a thin piece a Teak plywood. This was the obvious place to put the panel, something was needed to cover this hole. |
|
 On
the right the new breaker panel has been installed. One nice feature of
this panel are the small LED next to each switch that show which circuits
are ON. |
|
 The
first circuit I added was power for my Raymarine SeaTalk instruments. I
have always provided power to the SeaTalk bus from the ST6000+ autopilot.
This was the simplest was to wire the SeaTalk instruments. To turn the
instruments on all I had to do was turn on the autopilot. This worked well
for years, although I had to keep the autopilot powered up to have
instruments when sailing even when I was using the Monitor windvane to steer
the boat. In Standby the autopilot draws very little current so this really
wasn't a problem in itself. However, I had seen some anomalies in the
instrument operation (e.g., the instrument lights dimming or turning off on
their own) and I thought it might be prudent to provide power to the
instruments separate from that to the autopilot.I had also added a number of low power electronics to my navigation station (SSB Antenna Tuner, NAVTEX, AIS, etc.) that had been added to other circuits. The new breaker panel would allow me to re-arrange these circuits in more logical and manageable configuration. |
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