New RV Owner with power(solar) questions.
Hi Everyone, I've enjoyed reading through the forums, and finally joined! I appreciate the wealth of information that is accessible here. My wife and I recently bought a 1985 LeisureCraft. It's ...
Forum Discussion
jsw513 wrote:
Where/how do the alternators come into play?
Ndeke Luka is built on a 2013 Chevrolet Silverado 3500 HD with a diesel engine. The engine is factory equipped with two 125A alternators and two starters batteries. (Chevrolet also has a very sophisticated charging system.)
Each of the starter batteries is connected to the camper battery bank by a fused 1/0 cable. The batteries are connected by a Magnum Smart Battery Controller whenever there is a sustained 13.2v charge on either side and disconnected whenever the voltage drops to 12.7v. (12.7v is typically given as "full" charge at 70F.)
This means that the batteries are connected together whenever the engine is running, whenever there is any significant light on the solar panel, or whenever I am connected to shore power.
Typically, the camper batteries are fully charged at sunset. Cooking dinner is usually 30 minutes at about 150A discharge rate, using the induction cooktop and the convection microwave. Additional loads are the composting toilet, refrigerator, lights, music/TV, telephone and computers, heat, fans, or air conditioner. Breakfast is normally another 15 minutes of 150A discharge. The net result is that I am usually about 125Ah down at engine start in the morning.
Being 125Ah down on a 600Ah battery bank usually causes the camper batteries to demand around 150A from the alternators for an hour or so. On a sunny day, the batteries are usually fully charged by noon. On cloudy days, the recharge rate is obviously lower and much more dependent on running the engine.
The design goal was three days with no sun or engine run.
Air conditioning is the greatest challenge as the fan is 10A and the compressor about 50A. Clearly, air conditioner run is dependent on temperature; that is, how long and how often the compressor runs. One "cheat" is to run the engine for 30 minutes to an hour during the initial cool down, just as one might run a generator.
There is no magic in any of this.
