Yeah I yanked the chain to provoke all this and it is for a reason. A good one... Knowledge.
All of us are not engaged in an argument. We are expressing different DESIRES for obtaining our ends. They differ. No one is "right" and no one is "wrong". Each of us is going to arrive at a different conclusion using different philosophies and each conclusion is absolutely valid.
I took a sharp stick and poked so as to stimulate the issue to get folks to declare their desires with a charger unit. What goals, and what parameters they intend to use.
Landyacht I owe you a debt of gratitude your sacrifice saved me from dialing up the buzz and freaking when I saw semiconductor temps headed for mars.
I am preparing to run a minor test and find voltage amperage relationships that are device limits for the Cheapowatt. This will give me something to do when I get back to the lab. It may well be that the cheapowatt must have a sizable charging capacity reserve to safely bulk charge a single RV battery at 14.7 volts. In fact now I am reasonably convinced it must. And one unit isn't going to cut it. Not even for a single battery. Not set at 14.7 volts.
But paralleled units will most likely will immediately rise to absorbsion limit. The ultimate generator shortest run time. If it takes 88 dollars worth of cheapowatts to charge series parallel three cell batteries I want to know that too. Maybe it'll take 132 dollars worth. Whatever it takes to not over-drive the units and get the job done. 180 amperes of charging power is no joke. Can ALL of them be reasonably expected to be controlled by a single pot. Going to find that out too. What resistance is needed to limit the pot to an acceptable safeguard high limit? That's right, a limiting resistor.
What some folks (not you guys) seem to conveniently forget is that many motor homes are built on Ford Chassis, and those chassis may have hairpin ND alternators. Start the engine and whoa baby, 270 amperes INSTANTLY. C20 charge rate? You must be joking. Three stage charging You bet. Start engine, Run Engine, Shut off engine. Voltage regulator remains in the high thirteens and young fourteens for sometimes days on end cross-country. Carefully cultivated C10's and C20's get tossed out the window sooner or later on trips.
Frazzled? Landyacht? You bet. That's why I grabbed a pointed stick. Each of us has a perfectly valid point and a perfectly valid objective. it just needed a little clarification.
However, and this is a biggie. I beg you all, to keep going as is. Lavish detail. I have yet to start and I feel guilty.
To reiterate: My objective is to charge batteries as quickly as is safely and sanely possible. Absolute minimum generator run time. For the pickyunish, quickly and safely is NOT defined as "Just Short Of The Point Where Batteries Blow Up" If you demand definition, quickly as is safely and sanely possible is the the point at which absorbsion limit DOES NOT CAUSE an undue rise in plate temperature or excessive gassing. Charge time limit will be forgiving up to a point. it's still "Spin That Timer Dial Time" to control total kWh returned.
Is all this worth it? Go stare at the price of gasoline, and more importantly the cost to go refuel. My sympathies lie with remote boondocking campers. The ones that park in deep shade of tall firs or redwoods. Oh by the way regular gasoline costs FIVE DOLLARS A GALLON PLUS near Yosemite Park.
Hopefully by sticking together a unified project result will emerge. A fellow RV'er can persue the data, pick what suits hum best then do handstands. All this has never been done before. keep it in mind. You guys are pioneers. We may be heading for separate destinations but every destination is valid.
I hope this clarifies things at least from my end.
