I want to make sure I have this correct.

[Markw]

I will soon be getting things together to hit the road and I want to make sure I have some things right before I start planning the electrical system.

Sizing the battery system:

1. I am considering LifePo4 for the batteries (though having looked around a little I see they are a bit expensive).  What would the pros/cons be over other Lithium choices?

2. I have seen people referring sometimes to Amp Hours and at times Watt hours...which should I consider when sizing my system?

3. Assuming I do my calculations by Amp Hours...if a device says it uses, say, 15 amps but I only use it for 1/2 hour a day does that mean I count it as 7.5 Amp Hours?

4. What variables should I consider when looking at solar panels, charge controller etc?

 

[tx2sturgis]

1: LiFePo4 are less susceptible to thermal problems, and with built-in BMS, they tend to be safe and they will last quite a while.

2: Both. You need to be fluent in both amp-hours and watt-hours.

3 Yes, you are correct.

4: All of them! Well, maybe not operation in absolute zero, but almost all other reasonable variables need to be considered.

 

[Markw]

I should probably  have worded #4 better.

Was looking for things like:

If I use 24 volt solar panels, do I have to use 24 volt batteries?

Should I add fuses to the wires from the solar panels?

When adding 110 sockets, should I use the ones with the breakers in them?

Kind of little  gotchas that people may not think about.

 

[tx2sturgis]

Kinda hard to guess what questions you have unless you type them out for us here. But we will try to help.

You can run higher voltage panels (20-40v) (or lower voltage panels in series) into an MPPT controller and it will properly charge 12 or 24 volt batteries.

On small to mid-sized systems, fuses are optional for the panels themselves. But fuses do provide an easy way to electrically disconnect a panel if you are testing it (or it has failed or shattered, etc)

Your question about '110 sockets'....hmmm. Well if you are wiring up a 12v to 120v inverter with hardwiring, they will usually have some kind of protection, both GFCI and circuit breakers.

Or, if you are referring to installing shore power outlets, then yes, they need to have circuit breakers (or fuses in some situations) upstream, such as in the combination 120v to 12v converter/power center. There should be at least some GFCI protection but this can be tricky. These can be 'fooled' into 'nuisance trips' just from a rainy day, and you hop into and out of a metal van or trailer onto the wet ground.

 

[Weight]

You can use 12 volt battery. The charge controller adjusts the panel voltage to the battery voltage. But to simplify things buy nominal 12 volt panels to match 12 volt battery. In general, the wires from the panels are sized to carry the short circuit amperes of the panel and no fuse is needed. There should be a switch to disconnect the panels from the charge controller. 110 meaning 120 volt alternating current? You must have a shore line connection or an inverter to have 120VAC. Having an inverter to power 120V outlets is a different question. Some 120V outlets have ground fault interruption, that is different than a breaker. A breaker, or fuse, protects wires. They must be at the end of the wire where the power inters the wire.

 

[Weight]

If my van is plugged into mains power and a GFI device tripped off when I touched the vehicle and mother earth, I would unplug the cord and investigate the problem. Fix the problem before re-connecting to mains power. Shore Power, Mains power, Grid Power, Camp Ground Pedestal all reference the same commercial power supply from a utility company.

 

[Markw]

Thank you for the replies!

I know these may seem like basic questions to some, but I just want to make sure I get the electrical right so I don't blow the system or injure myself.

Aside from the vehicle itself the electrical system is probably going to end up being the biggest expense and I just don't want to screw it up.

Quick question about batteries.  Is it better to go with, say, two 100ah or one 200ah?  What are the pitfalls with size mixing (example: adding a 100ah battery to a 200ah)?

 

[tx2sturgis]

A typical 200 ah lead acid battery is REALLY heavy. So it depends on: can you, even with a helper,  physically carry it into where it will be located? Will the floor (or frame it sits in) support it? Will you be able to counterbalance it's weight on the opposite side? What if in a couple years you have to move it out and replace it? 

Two 100 ah batteries are a bit easier to deal with. Typically can be carried one at a time by one (sturdy) person, and can be physically spaced out or placed where the weight can be dealt with.

Also, consider purchase cost and shipping cost, if ordering something that heavy. There is NO SUCH THING as 'free shipping'...they just increase the cost of the product to cover the shipping costs.

Look around locally and see what can be found, and at what price.

Mixing different capacities in the same bank can be done, but mixing different chemistries (ex lead-acid and lithium) should NOT be done. 

Mixing different capacities increases complexity.... 'best practice' is to buy matching batteries all at one time. If you don't or can't buy enough, or have to replace a failed battery later on, then that is the time to open a conversation about mixing capacities. 

But not in the beginning as you plan the purchase.

 

[Markw]

After watching videos, looking at prices and such on Amazon, here's what I am thinking.

Main electrical needs:

* 12v compressor fridge (likely a 30qt since it's just me).
* Laptop (quite a bit of use as I tend to do a lot of research as well as some gaming.  Nothing like ghost recon or call of duty...think simcity level gaming)
* Charging cell phone and maybe a hotspot.
* LED lighting.
* Fantastic fan or something similar.
* Probably a small instant pot that I likely won't  use every day.
* Coffee pot that will most definitely be used every day...probably twice a day (I love my coffee).

My initial thoughts on the electrical system:

* 2 x 100ah Lifepo4 batteries (probably Ampere Time or similar...I know Battle Born is really good but they are too expensive).
* Properly sized MPPT charge controller.
* Appropriate fusing and wiring.
* 800 watt inverter (haven't researched branding).
* 100 watt solar panel on the roof plus a 100 watt portable panel (I will likely be starting out in a minivan, which means limited roof space...unless I can fit a 200 watt panel in which case I will go with a single 200 watt panel...probably Renogy as they seem to be the recommended for lower cost panels).

Am I at least on the right track as far as the electrical system considering my needs?

What recommendations would you make for changes? Bigger or smaller solar array? Different size inverter? More/less battery?

 

[PeterPiper]

I got 120Ah LiFePO4 batteries from here
https://www.amazon.com/gp/product/B08RWSZNNG/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

And I have been MORE than happy with them.

But these are 4 cells and not a complete battery.
I went the complete battery route first and was disappointed on several fronts. At the time I knew little about LiFEPO4 batteries.
I quickly learned a LOT, added my own BMS and I am VERY happy with the batteries I have now.
I also have FAR more flexibility with managing them.

If you're going to be doing this on any kind of a budget, do yourself a favor and learn all you can about the batteries, a BMS and their setup, care and handling.
It's not as complicated as it may seem.
Everything you do somewhat centers around the batteries.

 

[PeterPiper]

Just an opinion, of course

 

[Cammalu]

Santan solar has 100 and 250 watt panels for $50
I have several

 

[Markw]

I was leaning more towards this battery.

https://www.amazon.com/LiFePO4-Batt...fepo4+100ah+ampere+time&qid=1630685529&sr=8-3

I know I lose 20ah, but the price is comparable and comes with a built in BMS.

 

[Markw]

Hmmm...looking on Amazon it seems like the only 800 watt inverters I can find are brands I've never heard of (although I have only looked at pure sine inverters...which is what I want).

  I may need to go with a 1000 watt.  Currently thinking Renogy or Xantrex (thanks, Bob!) since it's at least a company I have heard of.  I mean, obviously I have heard of like Energizer and Duracell but I don't want to buy an inverter just to check it off the list.

Thoughts?

Cammalu: thanks for the heads up!  Do they do installs?

 

[tx2sturgis]

Delete the electrically powered heating appliances!

Delete the instant pot and the coffee pot, and you have a fighting chance with a 200 watt (split portable and roof) system powering a laptop all day and the other stuff intermittently. 

If you deplete the battery down with an electric coffee pot and/or an insta-pot, your system will be falling flat in the first 2 weeks.

All is not lost, they have this compact, inexpensive energy source, called 'propane'...maybe you've heard of it?

Buy a little campstove or single burner stove and cook your coffee and meals on that. They work.

If you do that one thing, your solar and batteries and laptop and hotspot and cell phone and LEDs all together put will very little strain on your system....and it should be able to survive even dark cold rainy days in winter.

Now if you had 500 watts of solar, that can all face the sun even in the low sun angles of winter time, you could make the electric powered cooking a reality.

But your system will be lucky to put out 50-100 watts in winter. That's just not enough to sustain frequent electric-powered brewing/cooking.

 

[Markw]

Lol yes I have heard of propane...but I don't like the smell.

I do plan to get a butane stove, though, for most cooking...maybe I can find a coffee pot that will use that instead of electric?

As for the instant pot, I can take it or leave it...just seeing more videos lately of people using them.

 

[tx2sturgis]

Your system as planned will do for very minimal needs. 

But as soon as you hook up a 1500 watt inverter and plug in an electric coffee pot, espresso machine, or coffee maker and run that for 15 minutes you are putting a big dent in the battery reserve that has to replaced. Then power up an insta-pot for however long...a few times a day...and then do this day after day and then having to pump out 50-150 watts all day to run a laptop...and the duty cycle on the fridge has to figured in as well, then add in the cell phone, and LED lights...a 200 watt system with one portable panel and one on the roof is not that powerful. 

I have 3, 100 watt fixed panels and 1, 100 watt portable panel (for my non-fulltime rig) and my system can not run an inverter for electrical heating or cooking. I can run high-power appliances for a few minutes...but that is all.

Your expectations are too high I'm afraid.

You can always cook outside with propane or butane, when the weather cooperates. That's what I do. 

Or you might be able to cook some meals over a campfire. Depends on your choices for food and what you can keep in the fridge, where you are camped, etc.

Now, if you wish to carry a small generator, then things get more user-friendly...you have more options of what you can operate daily. But then there is the noise and gas and extra weight.

Your call.

 

[Markw]

I do intend to have a small generator for those times when the weather just isn't cooperating for several days. I plan to treat it like emergency power, not a steady use because the solar system can't keep up item.

As for the 200 watts of solar...that's me assuming I will end up in a minivan (meaning limited roof space). If I have room for more solar, I will definitely add more...it just really depends what I end up in.

Like my parents always told me "hope for the best, expect the worst and you will never be disappointed".

 

[Weight]

I have an Samlex 2000W sine wave inverter. I highly recommend the brand.

 

[highdesertranger]

heating anything with only 200 watts of solar just ain't going to happen. You need to do the three step,

1. calculate daily energy use
2. size your battery(s) according to #1
3. size your solar according to #2

you will find out quick heating with electricity is an energy hog.

Highdesertranger