This is a nerdy one.
We have a huge 210 Amp Balmar alternator on the engine. It’s controlled by a separate Balmar MC-614 Charge Controller.
We also have a huge 400 Amp solar array mounted on the pushpit. It’s controlled by a Morningstar TriStar MPPT charge controller.
The purpose of the two charge controllers is to give our huge(ish) battery bank what it wants. What our battery bank wants is maximum amps until it’s at 14.4 volts, then 14.4 volts for a couple of hours until it’s mostly charged, then 13.2 volts for a long time to “top off” the charge.
Even though they don’t really communicate with each other, usually the solar charge controller and the alternator charge controller work well together, mostly because the batteries aren’t that picky.
However, we’ve had a few times where we’ll be motoring along on a sunny day and the tachometer signal will disappear, often while we’re anchoring or entering a harbor or are otherwise distracted.
Here is what the deal is: The batteries are full but the charge controllers are somehow off synchronization. The alternator controller is trying to hold a trickle charge of 13.2V, but the solar power controller has decided that the batteries really need 14.4V and pump in the juice. The alternator controller sees the higher voltage, thinks that the world is coming to an end, and faults out.
It would be fine if all it did was shut down the alternator until we re-started the engine, but the alternator controller also puts out a synthetic tachometer signal that the engine control panel uses to tell the meat how fast the engine is running.
So, now, if the tach shuts down while we’re running, we close up or cover the solar panels. Problem solved.
Rodney and Denise came up to go sailing, but the boat had a hole in it and was not sail-able so we worked instead. We installed the four 100W solar panels.
We hinged the panels together with aluminum hinges riveted to the aluminum frames with aluminum pop rivets, set in Tef-Gel, a teflon paste that’s permanently sticky and messy.
Then we attached stainless steel collapsible braces on the sides of the panels and mounted the panels on the aft rails with the same stainless steel pad-eyes we used on the swim step. We used stainless steel pop rivets, also bedded with Tef-Gel.
While I drilled a hole in the deck to connect the panels to wiring in the lazarette,
…Rodney wired the panel into the MPPT (Maximum Power Point Tracking) charge controller in the engine room. The MPPT matches the output of the solar panel, which constantly changes with the sunlight, cloud cover, and shadows, to the requirements of the batteries that need specific voltage and currents depending on their state of charge. The MPPT controller effectively makes the panels 30% larger. Rodney also cleaned up a large part of the wiring mess and generally made the engine room a nicer place to be.
I bought two stainless tubing braces, one to use on starboard and one to port, but we decided that we needed to use both to make the port panel stiff enough when deployed flat. So the starboard panels are waiting on UPS to be installed.
Nancy and Denise worked like mad while their men worked, but there are no pictures, so it’s like it didn’t happen. I’m sure it was all mission critical, though.
These four panels were the last pre-punative-duty Chinese solar panels to make it into the USA. We paid about $1.50/Watt, which is almost an appropriate price. They are also very well made. This last weekend the most we saw was 104 Watts from the 200 Watts of installed panels. We should get closer to rated power as we move south.