Wiring Woes

[erfnie]

We've come to the point in our build where we need to finalize some decisions about the electrical.
I've been doing so much reading and researching in all these posts that my head is spinning.
I'm hoping some of you can help me reach a little more understanding on all this.
Some basics of our plan:
Both AC and DC - outlets in cabin and outlets in galley to occasionally... charge a phone? use a laptop/dvd?
(we don't usually use electricity when camping)
Vent fan
Cabin lights LED
Galley Lights LED
Porch lights LED
Water pump
Battery on the tongue
Fuse and disconnect on cable near battery (not figured out yet, see questions below)
Power Center at the back of the cabin in upper cabinet

Here's even a rough drawing of our plan, laid out like it would be on the teardrop.

Now some of what's making my head spin...
Thought we would go with the Progressive Dynamics 4045, but now thinking that might too much for our needs. Should we go with the smaller 4135 instead?
And is a unit like this really that much easier? Sounds like many have confusion with the installation?

The wire run from the battery to the power center is 15 ft, going through the ceiling cavity. We already bought 6AWG cable according to charts showing the voltage drop and estimated load. But is this still too heavy for our needs? What fuse goes on this gauge? Or should we go with a lighter 8AWG? Then what fuse?

What size cable goes from the shore power inlet to the power center? (It's a 3 foot run - does that even matter?)

I see many wiring diagrams using 12AWG or even 14AWG to lights and such that likely draw less than 1 amp. Isn't that over doing it? Isn't 16 or even 18 AWG more reasonable?

And finally, (for now) what size battery is a good choice? I know they have different amp hour ratings. Do we need to match the battery size to whatever power unit we get? Or to the amp usage in the whole system?

Please forgive my ignorance on some of this. I'm not even sure I'm asking the questions correctly. I'm no stranger to working with diy electric stuff, but when it comes to batteries, DC and converters and such, it's like a foreign language ugh!

Erfnie (and Azua)

[tony.latham]

Both AC and DC - outlets in cabin and outlets in galley to occasionally... charge a phone? use a laptop/dvd?
(we don't usually use electricity when camping)

I'm pushing towards two decades of teardropping and have no need for 120V AC. There is a small inverter in the tongue box but I can't recall when we last used it or what it powered. Why not just stick with DC?



We use our electrical system to charge our phones, run the vent fan, power the Propex heater, my CPAP, two LEDs and sometimes charge up an iPad. If we ran all of that stuff at once, we'd be using about... 4 amps/hour. And we never have all of that stuff going at once. We're camping.

I run 12 AWG from the battery to the fuse box (because of distance) and then 16 AWG to each appliance.

So yes, you are thinking about using wires that are too heavy. (8 AWG? 30 amps?)

And finally, (for now) what size battery is a good choice?

I can't answer that based on your data --how many days will you be out? Unless it's very warm, we don't run our fan. When we do, it uses 1.5 amps/hour. It takes a couple of amps to charge our phones. LED usage is so low that they are hard to measure. A water pump shouldn't use much juice since it's not going to run for very long.

Keep in mind when shopping for a Marine/RV battery, you can only use about half of what they are rated for without damaging them.



Tony

p.s. Fuse size? There are lots of online charts to determine what fuse is needed to protect a given wire size. All of my circuits have 7.5 amp fuses.

[erfnie]

Hmmm... you've definitely given us something to think about.

Why not just stick with DC?

If that were the case, then do you still need something like the PD4045? And a shore power hookup? Cuz how does the battery recharge?
What if we were to add solar later on?
And if you don't mind me asking, how do you run a CPAP from DC? Is there an adapter to plug it in?

[GTS225]

And if you don't mind me asking, how do you run a CPAP from DC? Is there an adapter to plug it in?

I don't know about his, but my machine has a step-down power block between the 120V plug and the actual machine. It drop the 120vac to 12vdc, so if one were to get or fabricate a cord that your machine could plug into, and hook up to a power port, you'd be golden. If your CPAP has such a power block, take note of the printing on it. You should find a "input power" and "output power" designation on it that will tell you what's up.

Roger

[tony.latham]

If that were the case, then do you still need something like the PD4045? And a shore power hookup? Cuz how does the battery recharge?
What if we were to add solar later on?
And if you don't mind me asking, how do you run a CPAP from DC? Is there an adapter to plug it in?

A PD4045? No. Just a Blue Seas fuse block that has a negative bus on it.

I can charge while towing or from the sun. I've got a 100-watt panel on the roof and a 30 watt panel on the tongue box. (And yes, you can add solar later especially a suitcase system)

CPAP? To begin with, they are a DC device with an inverter with the factory cord. I bought a12 DC power cord for my Phillips but Resmed makes one too. In the photo of the fuse block, three's a 12v outlet to the right. That's where my CPAP plugs into.






Tony

[tony.latham]

And for stationary charging, you could add one of these ports along with a 120v smart charger.

https://www.amazon.com/NOCO-GCP1-16-Inch-Integrated-Extension/dp/B009ANV81S/ref=sr_1_2?crid=ILWDK37TT6OG&dchild=1&keywords=noco+power+port+receptacle&qid=1587856613&sprefix=noco+pow%2Cdigital-text%2C215&sr=8-2

I put one in my sister's little 'drop.





Tony

[John61CT]

The PD "converter" is a charger, shore power in, DC out.

Can also take genset input.

None of which has to do with powering AC load devices

which inverters do that from DC input from the battery.

[bdosborn]

I'm pushing towards two decades of teardropping and have no need for 120V AC. There is a small inverter in the tongue box but I can't recall when we last used it or what it powered. Why not just stick with DC?

I'm with you, I have a nice 300W inverter I haven't used for years. I keep it just in case but so far that case hasn't cropped up.

Bruce

[erfnie]

And if you don't mind me asking, how do you run a CPAP from DC? Is there an adapter to plug it in?

... your machine could plug into, and hook up to a power port, you'd be golden. If your CPAP ...

Maybe I should've been more generic. I don't actually use a CPAP. I was just wondering how "any" device usually plugged into household AC (or so I assumed was the case with these), is plugged into DC instead. Thanks for the info, tho.

In the photo of the fuse block, three's a 12v outlet to the right. That's where my CPAP plugs into.

Ok, I was wondering what that was for.

And for stationary charging, you could add one of these ports along with a 120v smart charger.

I'm very intrigued by this port. Could you explain the system and components behind it (what's on the other end)? Is it only DC like yours? Does it use an inverter?

Can also take genset input.

John, sorry, I have no idea what this is.

[tony.latham]

Could you explain the system and components behind it (what's on the other end)?

It's just an exterior outlet to plug in a 120-volt extension cord. The interior end is a female connector for the same. That's where you'd plug in a charger inside your 'drop.



Tony

[erfnie]

...That's where you'd plug in a charger inside your 'drop.

You mean a charger to charge the battery?

[troubleScottie]

You always need a charger for your battery.

You could do it like most people do their car ie open hood/bonnet, disconnect battery, attach charger, charge for n hours, etc.

This fine if you do this once in a while. More likely you want to have a charger installed and permanently connected to the battery and to a mechanism for getting to the outside of the TD.

There are lots of variations for a charger: a stand alone charger ( battery tender, genius, etc), a converter often built into a power distribution center, solar MPPT or DC-to-DC MPPT charger. All could exist at the same time if you liked. Connection to the outside could be 120VAC 15amp/20amp/30amp/50amp sockets or just running an extension cord outside. You do not need a distribution center for most of these devices. You do need some sort of AC input for the charger or converter.

To the OP, in concept, you do not need any AC while you are camping. So a power center and AC outlets are NOT required. Hence the initial response. You can recharge when you get home. Most devices are either already dc or can be gotten in dc versions eg LEDs, usb ports, TVs, radios, frig/freezers, water pumps, water heater, propane/diesel heaters, fans. They are reasonably reliable and are sized for RV and TD.

The only devices that require AC are the big draw motors or heaters. So air conditioning, space heaters, coffee pots, crock pots, microwaves, big frigs, ice makers, electric blankets to name a few. Using an inverter ( DC to AC) generally is not practical for big draw items. (look for other threads on inverters). If you are not using or planning on using them, AC does not have to included. If you do want these, the power distribution center is the way to go. Simple, all-in-one. Remember to have at least one external AC outlet if using an external AC unit.

[tony.latham]

...That's where you'd plug in a charger inside your 'drop.

You mean a charger to charge the battery?

Yes. When you're parked near an outlet.

T

[Shadow Catcher]

Probably two thirds of our camping includes shore power, just the nature of where we are. If you have it you might as well use it.
There are four duplex 120V outlets in the cabin and four outside. There are seven 12V outlets inside and three outside. They pretty much all get used. Chargers for cell lap top, Mifi cell signal booster etc. Water heater might as well use the electric rather than propane, coffee maker rather than the French press. I always recommend have more than you think you need.

[John61CT]

Can also take genset input.

John, sorry, I have no idea what this is.

Generator, gennie jenny genset

converts fossil fuel to AC power, output.

Substitute for shore power when off grid.

Noisy and expensive supplement to solar, or alternator use while driving.

Common example Honda EU2200i