AStravelers said:
As an example, we went to Alaska on a 4 1/2 month trip (139 days) in 2016. Our 400AH lithium and 650watts of solar allowed us to boondock/dry camp for 137 of the 139 days. We only ran the generator for charging for about 2 hours one time on that trip because of a string of days very cloudy weather. Note, our house batteries don't charge from the engine while we are driving. We use the TV and satellite receiver for 3-5 hours a day. Two laptops for 4-6 hours a day, some microwave usage to heat things up, a toaster some mornings. We do use a catalytic heater instead of the furnace for heat. At night we have lots of blankets/quilts on the bed and leave the heater off. My wife uses a power wheel chair and also a 4 wheel power scooter when we are out and about. We charge both of them through the inverter as well. The two days we had elect hookups was because we stayed in an RV park and because we could we plugged into shore power.
We also consistently travel and dry camp. Currently we are 7 days into a 7-8 week trip though southern NM, AZ, & CA. We have no plans on staying at a place with elect hookups or using our generator.
Hi Al - Wow, thank you for the time and effort for your posts. I know how much of an investment such detailed posts require. My overall reaction was "Hey this is WONDERFUL, really GREAT"! Real life experience indicating that I'll have enough power to live as I envision, which of course means conservation and keeping track of where my batteries are at. My estimates are just that - because you have to start somewhere, so I may be guilty of being overly concerned at this point, but this derives from the fact that the final decisions about the system are imminent and is due to not having experience living the RV lifestyle . . yet!
Except for info from my 120V appliance baseplates and a couple of wattage numbers from the TT manufacturer, all my other watt/amp/amp-hr information has had to come from web resources. I've been collecting info on electrical requirements (off & on) since Sep 2016, so the time had come to compile it into something I could see, on paper, and study. What I've determined is that information out there about electric usage for specific items varies WIDELY - for the same item. And, I need to try and get usages that match the equipment I have. For example, televisions - the amp draw varies widely depending on the size TV and whether 120 vs 12V. LED lights are another example, but they don't contribute much to the overall total so I'm not concerned about the range reported, but still. . . . I have seen published info that a 12W LED bulb draws anywhere from 0.12 to 0.2 amps. That's kinda a large INDIVIDUAL difference -- and can lead me to wonder about the published accuracy of other bigger ticket items -- like the furnace fan. Due to these vagaries, differences, and my lack of trusting the numbers, I may be over-estimating, "just to be on the safe-side" as they say.
But, for whatever reason, my barebones usage still comes to around 180 Ahrs per day. No microwave cooking -- only heating water for my Melita pour-over coffee filter, reheating coffee and food, no hair dryers, no furnace fan, no satellite, no excessive computer or TV use, no slow cooker or instant pot use.
To make it easier maybe, if anyone is interested, I've attached a revised, mostly completed
ESTIMATE TABLE that lays it all out. I've separated the "occasional use" items, and included a column for their daily usage, so I can see their impact IF and WHEN they are used. I've listed the furnace fan as SEASONAL, and not for example, included any furnace usage in my "normal" expected daily routine. All this is simply an attempt to capture the "most likely scenario" for daily usage and see how much excess capacity I may have for cloudy-days, or needing the furnace, etc. I am not trying to size the system to use high-draw non-essential items (like iron, vacuum, toaster, etc.) on a daily basis.
As Gary the Emeritus has so aptly pointed-out "Propane is my friend while boondocking" Heck yes, I can boil water for coffee on the stove, my Coleman stovetop/grill, or even my ole MSR camping stove. I don't NEED to use a microwave for example. But is it more convenient all around to do so on a regular basis?. . . yes.
Any system design kudos go to AM Solar. I simply sent them info on the TT layout, where I wanted to system to go, and how I planned to use the TT. They did in fact come up with the 720 W of solar panels and the 600 Ahrs of battery. By some magic, this is the same size system I had envisioned based on my earliest estimates (now refined somewhat).
Yes, I'll have a 1000 watt genny (biggest I can lift, and no, I don't want to connect 2 of them) but I don't want to have to use it on a regular basis. It's for emergency power (slide, steps, tongue jack etc. use) in case of system failure, or to add necessary battery amps IF I should get stuck in sunless conditions that threaten my essential daily needs, in spite of conservation.
I see what you are saying about monitoring for the total amps in/out of the battery. I'll have to clarify this with AMS - they will likely call on Monday I think. We have only had a one hour discussion so far, and while a lot was covered, there are still some details to pin down, so I'll add this to the list. I do think I remember being told there is a direct read-out on the monitor for the percentage of battery charge remaining however. It's not something that has to be calculated from amps out and in as I recall. Will address this however.
AMS is currently using 100 and 180 W panels. Mine will all be 180 W. And you are correct, I don't know if they will do a combination of series and parallel for the solar panels or not. Can't really tell from the estimate they have provided. This is an area I trust their expertise. Same thing for the wiring, I trust their judgement.
The charge controller is a SunRunner Victron MPPT 85A. According to the specs, this controller can handle solar inputs of up to 1150 W. It is rated at 85 amps. This is getting into the details with which I am the still the least knowledgeable, so here is a link to access the Datasheet on the controller if you'd like to check it out. Mine is the 150/85.
https://www.victronenergy.com/solar-charge-controllers/mppt-150-70
With the input from the good folks here, and AM Solar's expertise, I think I'm getting excited again about how great this is gonna be. Al, your solar system sounds awesome, and works exactly like I would like mine to operate. I will be in RV parks now and then, -- laundry, longer showers, other amenities, change of pace, using those cooking appliances and freezing soups, chili, pot roast and stew meals (not all on the same day obviously), but I would like to NOT have to stay at one simply to charge batteries, although if such an occasion should arise, that's okay to and I'll deal with it.
Thank you again,
Linda