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Melissa & Dave - Adventures at Sea

Electrifying Upgrades

Electrical systems on boats are complicated.

There are two sets of batteries - the starter battery which starts the engine, and the house batteries which power everything else from the kitchen lights to the toilets.  You always want to isolate the starter battery from the house batteries so that even if you run the house batteries out, you should always be able to start the engine to either (1) generate more power, or (2) deal with an emergency in the middle of the night like your anchor is dragging.

Then there are multiple charging sources: shore power, main engine alternator, solar, and the generator.  We’ve been using a small Honda generator ever since the built-in generator caught fire.  (Someday that will get fixed, but since it quite likely involves taking a saw to the kitchen cabinets, even McGuyver is hesitant to start that repair.)  There is even a little solar cell on the cabin top connected to the start battery but it is 20 years old and it probably doesn’t work. Shore power, main engine and Honda all charge the batteries at about the same rate. The solar puts out about half of any one of the other sources - not enough to run the whole boat, so we supplement by running the generator a couple of times a day for an hour or so.

There is an automatic combiner connects the two battery banks together once the voltage rises to about 13.5 volts and disconnects them when it drops to 12.5 volts. The idea is that when there is a charging source, all batteries will get power. When there is no charging source, the start battery is isolated so it won’t be discharged by the house loads.  At least that’s how it's supposed to work.

The main engine alternator is connected to the start battery. Ideally, it would be connected to the house bank which is always more hungry than the start battery. When the main engine is running and the house batteries are low or the fridge is running, the voltage drops and the house bank is isolated. The voltage then climbs back up and the isolator connects the banks again. This cycles every minute or so putting unnecessary wear on the start battery.  So ages ago, Dave moved the alternator over to the house battery bank to prevent this wear and tear. Or so he thought.

A gorgeous 4th of July weekend we head to Winslow with plans to watch the Seattle fireworks from anchor in Eagle Harbor.  Dave goes to start the Honda generator. It's been giving him fits for a while - he’s lost track of the number of times he has rebuilt the carburetor.  So when he went to run the generator that afternoon, he wasn’t surprised that it kept quitting. He was suspicious that something was up with the oil, so he pulled the dipstick out.  And indeed there was something wrong - because a gooey mix of oil and gas came spurting out of the generator and covered the back deck.

Dave starts yelling at Melissa, “bring rags, come quick!”.  I wish I had a picture, but in the scramble to get the situation under control, taking a photo wasn’t my first priority.  It was a giant sticky black mess.

Ultimately Dave would later discover that the fuel pump had a hole in it which was allowing fuel to mix with the oil.  But that’s not exactly the obvious thing, and Occam's razor principle says it's usually the simplest explanation. So Dave figures that gas has been sitting in the generator for a while and has gone bad - all thick and sticky.  This likely gummed up the carburetor needle valve, which in turn caused the oil sump to fill with fuel.

So Dave heads up to Ace hardware for a clean gas tank, and then to the gas station for fresh fuel.  Back on the boat we drain the old fuel (now with debris, oil, and water mixed in) into the old gas tank.  Dave removes and cleans the carburetor, and changes the oil. At this point the generator ran for 15 minutes and died again.  At this point Dave threatens to buy a new generator. He starts up the main engine and charges the house batteries up.

So there we are sitting quietly at anchor that evening, hanging out watching a movie, when the boat browns out.  Clearly the house batteries were dead. This is no big deal - just start the main engine and let the alternator charge the system.  Alas, we discover the main engine won’t start. Hmmmm. The combiner must not have disconnected the start battery soon enough and now both battery banks are dead.

Now mind you, we are onto the backup to the backup plan.  Plan A when the batteries run down is the generator, plan B is to run the main engine.  But being paranoid, Dave always has a backup to the backup plan - which in this case Plan C was the purchase of a portable battery charger with a boost mode.  So Dave turns on the inverter - which allows him to suck the last of the juice out of the house batteries through the portable battery charger, and boost the starter battery.  Alas no dice. Plan D was always to run the 20 horsepower outboard dinghy motor which has a 12 volt output and charge the start battery. Alas the 20 horsepower motor is in the garage for maintenance.  Plan E is that Dave has a small battery he uses with the electric dinghy motor that might have enough power to start the engine - but he forgot to try that.  Plan F, during the 2 year cruise anyway, was an old airplane battery kept aboard as a spare, but its dead and no longer on board.  Plan G is to row to shore in the dingy and buy a new battery. Alas at this hour all the stores are closed.

So at this point Dave - reluctantly and somewhat begrudgingly - admits defeat and we spend the night entirely without power.  However, before going to bed, Dave realized he could at least disconnect the house batteries so that when the sun comes up, and the solar is generating enough voltage, it will trigger the combiner and charge the start battery.  So in the morning, by the time we awake, the solar panel has recharged the start battery sufficiently to easily start the main engine. And since we were headed home anyway, Dave decides to evaluate the electrical system upon our return.  At which point Apsaras received a number of upgrades.

The first order of business is to repair or replace the Honda generator.  So Dave brings it home to the shop. He installs a new carburetor only to find it still sucks fuel into the crankcase. Process of deduction says that the only other thing it can be is the vacuum driven fuel pump.  So he sucks on the vacuum line and sure fuel came through. None of the on-line forums ever hinted at this as the possible cause - all other reports were of a stuck carburetor needle valve flooding the engine.

Disassembling the generator to install the new fuel pump turned out to be a task. You have to remove all the plastic covers which involves 12 really hard to break-loose fasteners. Dave then installed the new fuel pump, along with a new carburetor, changed the oil (again), and Voila!  It runs like it did when it was new. He even installed a new gas cap on as the old one was rusted and dropping debris into the tank. Back aboard Apsaras, he loaded the generator up to 75% capacity, and its running flawlessly.  Apparently, little engines can survive seizing due to diluted oil and come back to life. We will see how long it lasts….

The last order of business on the generator repair was to figure out how to dispose of all that old icky oil and fuel mix.  Turns out you can just take it to the dump and they will dispose of it for you for free. Your tax dollars at work.


Now onto the batteries themselves.  Further investigation revealed that when we bought Apsaras a new set of house batteries when she returned from Panama in 2016, the charging circuitry was not programmed for AGM batteries.  Which resulted the house batteries not charging fully. Additionally, equalization also was too low of voltage so it was not ‘zapping’ the batteries enough to clean their plates. You are supposed to zap the batteries every month or after a certain number of discharges.  If you don’t do this, the batteries wear out too soon. Moreover, we had a hard freeze aboard Apsaras in 2017 that was also likely not good for the new batteries. And indeed, we discovered that the house batteries were no longer holding a charge and had to be replaced. The start battery seems to have come back to life though. [Note: A few days later we would discover that the start battery was also dead and ended up replacing it too.]

Dave replaced the two AGM 8D house batteries with a LiFePO4 battery. They are half the weight - smaller - survive complete discharges - live 5-10 times the number of cycles - and charge back up faster (less generator time).  You can see in the pictures how much smaller the new one is.


While Apsaras is ready to cruise again, there are still a few upgrades Dave wants to do at some point.  (There is always a list…)

During the investigation, he discovered that the alternator is not charging the house batteries, but is still connected to the start battery - which means its still cycling too much.  Someday Dave would like to change the way this is wired.

We should also replace the start battery solar cell with a modern unit. A new one doubtless would be much more efficient than the aged, 20-year old one that came with the boat. 


And while Dave plans to turn off the start battery while at anchor to preserve it, he also wants a new solar cell because the new ones are so much more efficient and would likely keep the batteries topped off much more easily.  Besides the generator is noisy!


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