Electrical Sizing Question

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Jul 8, 2019
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Hello fellow van dwellers!

I have some questions regarding my electrical system and sizing it correctly. I'm completely new to doing this so I appreciate you bearing with me on answering these questions.

Valence 12V 40AH Battery
I have decided to go with used 12v Valence LiFeP04 Iron Magnesium Phosphate batteries. I have a total of 4 that each have 40AH when connected in parallel equal to 12v 150AH total. From what I've heard, these batteries can be drained below 50% unlike lead acid / AGM counterparts. With that said I will break down my system WH.

I have 4 lights that each draw 3W per hour. A total of 12W that I've estimated I'll use for 5 hours a day. So, 12x5 = 60WH

I understand that the startup draws more watts but am only including the 55W draw for continuous power. I am factoring in 5 hours per day...
55x5 = 300WH

ARB 50 QT Fridge
Again, I understand startup draws more but am only including continuous power. Not quite sure how long most people keep their fridges running but I figured 10 hours throughout the day will be enough. 55x10 = 550WH 

The last part of my electrical system is 2 12v DC Socket adapters to charge phones etc, no more than for 1-2 hours. Does anyone have experience with how many watts this will draw?

If my math is right, thats a total of around 910WH

I have a 200W solar panel and am planning to use a battery isolator to assist the solar with charging the battery bank. So, does this mean that I can run my 12V system with a 1000 Watt Inverter? And if I am running a 12V system can I still use an inverter that is capable of plugging into shore? 

My last question is about the battery isolator itself. I understand that you can use any type of isolator when you are using lead acid / AGM batteries but if you are running a lithium systems you will need a unique isolator. I've seen 2 of them and I'm curious as to which one would work better for my system. Heres the options below VV

Battle Born Lithium Battery Isolator

Renogy 12V 60A DC-DC Battery Charger

I am by no means trying to half ass electrical in any way, and would appreciate any and all advice that you guys could share with me. Even suggestions and tweaks on my system itself would be greatly appreciated. Thanks for everything!

Happy Traveling
You'll be able to run those devices off 12v. The inverter is for things like a laptop that need 110v.
"So, does this mean that I can run my 12V system with a 1000 Watt Inverter?"

you don't run a 12v system with an inverter. an inverter converts 12vDC to 120vAC

"And if I am running a 12V system can I still use an inverter that is capable of plugging into shore?"

do you mean an inverter/charger? you don't plug inverters into shore power.

"but if you are running a lithium systems you will need a unique isolator"

you need a unique everything with Lithium.

also your numbers are way off. at least I think they are any way. I usually deal with Amp Hours(AH's) because that is how it was always done back in the day when rocks were young. the ARB refrigerator turns itself on and off you don't. just set the temp and leave it. most of your 12v refrigerators have about a 20% duty cycle, which means it runs about 1/3 of the time so look at the spec sheet and multiply what the manufacturer says the consumption is by 24 then divide by 3 this will get you real close depending on ambient temp.

here is what you need to do,

1. figure out daily usage
2. size the battery bank to #1
3. size the solar to #2

it makes no sense to jump in at #2 or #3.

highdesertranger said:
also your numbers are way off.  at least I think they are any way.  
Other questions aside, actually I think the numbers are a slight overestimate, which is never a bad thing. Right?