IMHO charging should be done late, not early.
This depends upon a lot of things such as solar, wind and what you used that day. You may not have discharged enough to make charging even worth while.
The best time for someone near me to charge is after dinner, say around 2000 to 2100, or 2100 to 2200, if only for one hr a day.
Funny that I find this one of the most obnoxious times to run anything. 8:00 pm to 10:00pm here is often the most peaceful time of day with the water becoming glass calm. Folks often sit and listen to the seals, Osprey's, Eagles etc. and sip wine and converse quietly in their cockpits. The calmness makes even "quiet" noises travel far distances. Here in Maine between 10:00am and 4:00 PM are the times when a generator will be best "accepted" as the wind is up and folks are out playing on paddle boards or swimming etc..
The reason: 1) That's when I'm most likely to run my diesel for an hour;
Here in Maine that will get you booed out of most anchorages. You would be doing exactly what you say you dislike, imposing yourself on others. Generator & noise acceptance is often locale specific..
2) Most cruisers are likely to be below by then so one of those "quiet", as you say, generators might not be noticed;
I might suggest that you could be seen to be making similar assumptions & justifications that many rude & inconsiderate generator owners do..
3) After a full day (hopefully) of solar charging, that's the time to top off the battery for the night and leave it charged up as much as possible through the night. The next morning when the sun comes up the panels take over early, etc.
Actually, from a battery charging perspective with solar, this is absolutely the worst time to use a diesel, generator or other IC engine for charging. In order to make running an IC engine worthwhile & most efficient the charger or alternator should remain in bulk for as long as possible. Bulk is just a fancy term for 100% of rated current output. This will best occur in the morning with solar. By the end of the day the bank should be at the highest point of SOC the solar can attain. Firing up an engine or genny to charge in the evening will very quickly raise terminal voltage, due to a high SOC, and the charge source will become "voltage limited" or hit absorption rapidly. Once the batteries become
voltage limited the charge current begins to rapidly diminish and the very, very, very long process of absorbing the batteries begins.
Absorption charging can take as little as 3.5 hours with higher efficiency AGM batteries at a charge rate of 40% of Ah capacity, to 7+ hours with standard flooded batteries. Running a generator at high SOC, above 75%, is simply wasting fuel that is not being efficiently converted to stored energy. Running any IC motor to charge above 85% SOC, unless that motor is doing something else such as powering a watermaker or engine driven refrigeration, is simply wasteful and quite meaningless in terms of actually storing energy, if that is its sole purpose for running.
On a typical cruising boat with solar and refer, running the engine or genny in the morning, rather than evening, the IC engine and AC charger or alternator will be used as efficiently as is humanly possible. During bulk charging nearly 98% + of the charging energy will actually get stored in the battery as usable energy. In the 85% - 90% SOC range as little as 30-40% of that energy is actually being converted to stored energy. In other words 30-40% of the noise you are having your neighbor to listen to is 100% unnecessary and 100% wasted energy. As we continue to push into the 90% SOC + range Coulombic efficiency is really low, and continues to worsen, and running any IC engine, specifically for charging becomes fools gold..
Getting through "bulk" or the constant current stage of charging early in the day allows solar to actually do what it does best and that is to
absorb or finish charging the batteries at low current to the highest SOC they can attain during sun up while also doing so quietly. Firing up a genny, after a day of solar charging, providing your solar actually charges the batteries, is simply being about as inefficient as it gets..
To have someone fire off his portable generator at the bow of his boat say, 50 ft or less from my cockpit behind me, while I might still be having coffee, reading, or just sitting out enjoying the morning
is THE PROBLEM
, especially if the exhaust is wafting toward me!
I'd much rather have a genset running in the am, preferably after 9:00 am, knowing it is actually working efficiently and doing something than hearing it run in the evening especially on a boat with solar.. Here in the AM boats are moving/leaving, kids start swimming, commercial fisherman are out etc.. In the evening it is entirely peaceful and often flat as glass calm.
Considering I have numerous world cruiser customers, who I design and install energy management systems for, who don't have generators, and who live on-board 24/7/365, and do so without a genny, the whole conversation IMHO is a frustrating one. If often comes down to the
entitlement attitudes so common in America today.
The real issues with the suitcase gens are safety and non-marine compliance with regards to the floating neutral. The secondary issue is
rude & entitled boaters but we can't really fix a sense of entitlement or a lack of etiquette & manners. Heck you and I both agree that suitcase gens can be obnoxious yet you believe running a motor at 2000 - 2200 hours is fine, and I find that rude and inconsiderate. Again, this is often
locale specific.
A lot has to do with your locale or region. Here in Maine suitcase gens are simply not well tolerated to the point where I have seen entire anchorages stand and cheer when an
entitled boater finally shuts down his noise maker. Still, even when we charter, I refuse to be obnoxious with generator use. This despite "everyone is doing it". It's funny how many boats I see
sail into an anchorage and then fire up the motor or genny once they get there to "charge".. Why not suffer the noise to yourself, while
sailing? It's due to an
entitlement attitude. They believe they are entitled and for their
sailing to be peaceful & quiet. Once they are done sailin, in peace & quiet, they then believe they are "
entitled" to impact everyone around them with their generator.. (grin) Annoy yourself, or annoy 30 other people..??? Does seem a bit "
entitled" to me... (shrug)
The OP has some system issues, and likely battery issues, as well as some fundamental issues in regards to understanding DC systems/batteries/energy use that need to be sorted. In order to actually help him we've not been given enough information.