Batteries for my Solar Panel

[siggy]

I'm totally confused about what I should do.
Should I buy one 200ah Lithium battery or two 100ah Lithium batteries.
My fridge is 12volt only. The solar panel is 165watt and the solar charger controller is an
Furrion MPPT 25A. Also are these difficult to install ?
Thanks

 

[Richpatty]

Not sure what you are trying to accomplish or what your goal is... As far as the battery, I would base it on cost and how it fits in the RV.

Solar controllers are not hard to install, just the wiring from the panels to the controller can be challenging.

 

[siggy]

Not sure what you are trying to accomplish or what your goal is... As far as the battery, I would base it on cost and how it fits in the RV.

Solar controllers are not hard to install, just the wiring from the panels to the controller can be challenging.

all the wiring is in the controller is installed. I'm just trying to see if I need one battery or two.

 

[siggy]

Not sure what you are trying to accomplish or what your goal is... As far as the battery, I would base it on cost and how it fits in the RV.

Solar controllers are not hard to install, just the wiring from the panels to the controller can be challenging.

all the wiring and controllers are in stalled. I'm just trying to figure out if I have enough solar power to have one or two batteries with what is already there.

 

[Rich W.]

As Richpatty said, one 200ah or two 100ah is more a matter of how it fits in the RV. The power storage is the same. I’d be more concerned about hoping to have enough charge by sundown with only 165w of solar. When you say the fridge is 12v only do you mean no propane or no 120v? Or both? Also what RV are you working with?

 

[siggy]

As Richpatty said, one 200ah or two 100ah is more a matter of how it fits in the RV. The power storage is the same. I’d be more concerned about hoping to have enough charge by sundown with only 165w of solar. When you say the fridge is 12v only do you mean no propane or no 120v? Or both? Also what RV are you working with?

First I want to thank you for your time. The fridge is 12v and 120v no propane . I have a Grand Design 2022 Imagine 17MKE

 

[Rich W.]

So you need to determine how much power that fridge uses (and also all your other misc stuff) taking into account that it cycles on and off, so some kind of average hourly usage would be handy. Then factor in about 70% of the max current your panel supplies because you never get 100%. Then you’ll know how much you used by sundown, and how much you need to make it through the night. Since you are starting with 200ah, and can probably safely use 80% of that, you have 160ah assuming full soc when you start out. Then you can determine your approx soc by morning when the sun starts contributing again. If you can get 7 amps out of your panel all day, thats around 70ah. But since you’ve also been using power all day you arent netting an additional 70ah. I know Im kind of rambling here and you may already know all this, but this is why I don’t think one 165w panel is enough. For every 24 hour cycle you will be using more power than you are making. You’ll have to plug in at some point to bring the batteries back to full soc. Some of this is trial and error because specs and reality always differ, specs being more optimistic. But you can get an idea going through the exercise above. Also of course by asking people who use 12v solar what works for them.

 

[siggy]

So you need to determine how much power that fridge uses (and also all your other misc stuff) taking into account that it cycles on and off, so some kind of average hourly usage would be handy. Then factor in about 70% of the max current your panel supplies because you never get 100%. Then you’ll know how much you used by sundown, and how much you need to make it through the night. Since you are starting with 200ah, and can probably safely use 80% of that, you have 160ah assuming full soc when you start out. Then you can determine your approx soc by morning when the sun starts contributing again. If you can get 7 amps out of your panel all day, thats around 70ah. But since you’ve also been using power all day you arent netting an additional 70ah. I know Im kind of rambling here and you may already know all this, but this is why I don’t think one 165w panel is enough. For every 24 hour cycle you will be using more power than you are making. You’ll have to plug in at some point to bring the batteries back to full soc. Some of this is trial and error because specs and reality always differ, specs being more optimistic. But you can get an idea going through the exercise above. Also of course by asking people who use 12v solar what works for them.

 

[B52Bombardier1]

Cloudy days are also not your friend. Yes, you will make some power but not as much as you think.

Are you still running incandescent light bulbs? LED lamps are miraculously low consumers of power and still produce a lot of light.

That your fridge doesn't run on propane is bad news for your power equation here.

Rick

 

[siggy]

No, you're not being redundant. I only have so much I can do right at the moment, so I have to spread my cost out. I think you just answered it for me. I'll get the larger battery then in 6 months i'll install the second panel. I do have a generator 3400W that I bring with me to top off the batteries when there isn't enough sun.
Again, thank you.