Inverter - Charger - Leave well enough alone?
Here, yet again, I have more questions... you all must be getting a little tired of me with these inquiries, and I very much appreciate the patience of those who've responded to my previous posts. My ...
Forum Discussion
I think you may be a bit confused about electrical units here, and what they're measuring. I hope this doesn't come across as overly pedantic; I'm writing it in hopes of helping you understand, nothing more.
You wrote that you figured your electrical use per day was 2000 watts. Watts are a unit of power, similar to horsepower; it's a rate of doing useful stuff. I suspect you probably meant that you require 2000 watt-hours per day, a unit of energy, but I'm not sure on that. 2 kWh seems rather on the high side to me particularly if you don't have a residential fridge, but you know your needs and so forth better than I do.
18 Amps is a measure of current, not directly equivalent to either power or energy. In RVs they do sometimes get used that way with the (often unstated) assumption that the voltage is known, either 12V for DC loads or 120V for AC loads. 18A at 12V is quite a different power level than 18A at 120V: around 200W for the first, and 2000W for the second.
Amp-hours, a unit of electrical charge, may be what you're thinking of for your 18A. 18 Ah at 12V is equivalent to approximately 200 Wh; 180 Ah at 12V is about 2000 Wh. Thus, you'd need maybe 200 Ah of battery capacity to go 24 hours without solar charging or generator use, etc. If your present batteries are 6V batteries, that's about the capacity of your present battery bank.
Note that it's not practical to use solar "only" without tapping into the battery bank, unless you only use power when the sun is shining. What I think you're aiming for, and it's a good plan, is to have sufficient solar capability that you can produce at least as much energy per day, on average, than you consume; if that's true, then you can operate indefinitely without needing a generator or shore power connection.
My initial impression is that you'd be better off investing in more battery storage than in additional solar panels. It sounds like you have enough, or close to enough, solar power to meet your daily electrical needs, but not much storage to buffer it between when it's available and when it's needed, particularly if you have a day or two of cloudy or rainy weather.
For most people, it's not at all practical to run an air conditioner off of solar power. If you wish to do so, it would make a lot of sense to spend some effort in better insulating the RV and probably in replacing the standard RV air conditioner with a more efficient model, perhaps a mini-split unit.
You wrote that you figured your electrical use per day was 2000 watts. Watts are a unit of power, similar to horsepower; it's a rate of doing useful stuff. I suspect you probably meant that you require 2000 watt-hours per day, a unit of energy, but I'm not sure on that. 2 kWh seems rather on the high side to me particularly if you don't have a residential fridge, but you know your needs and so forth better than I do.
18 Amps is a measure of current, not directly equivalent to either power or energy. In RVs they do sometimes get used that way with the (often unstated) assumption that the voltage is known, either 12V for DC loads or 120V for AC loads. 18A at 12V is quite a different power level than 18A at 120V: around 200W for the first, and 2000W for the second.
Amp-hours, a unit of electrical charge, may be what you're thinking of for your 18A. 18 Ah at 12V is equivalent to approximately 200 Wh; 180 Ah at 12V is about 2000 Wh. Thus, you'd need maybe 200 Ah of battery capacity to go 24 hours without solar charging or generator use, etc. If your present batteries are 6V batteries, that's about the capacity of your present battery bank.
Note that it's not practical to use solar "only" without tapping into the battery bank, unless you only use power when the sun is shining. What I think you're aiming for, and it's a good plan, is to have sufficient solar capability that you can produce at least as much energy per day, on average, than you consume; if that's true, then you can operate indefinitely without needing a generator or shore power connection.
My initial impression is that you'd be better off investing in more battery storage than in additional solar panels. It sounds like you have enough, or close to enough, solar power to meet your daily electrical needs, but not much storage to buffer it between when it's available and when it's needed, particularly if you have a day or two of cloudy or rainy weather.
For most people, it's not at all practical to run an air conditioner off of solar power. If you wish to do so, it would make a lot of sense to spend some effort in better insulating the RV and probably in replacing the standard RV air conditioner with a more efficient model, perhaps a mini-split unit.
