30amp to 12v or 120v?

[ependydad]

Ok, forgive my ignorance...

I'm dry camping at a primitive campground this coming weekend and I need very basic power - for limited light usage in the PUP and for a bipap machine (for sleep apnea) at night.

My battery on the pup was dead when I bought it, but it was never an issue because we always camped with hookups. And, I'm looking to sell the pup soon so I'd rather not invest the $$ in a new battery.

Here's what I have -
 - a pup with a 30am power cord
 - a Dodge Ram w/ 12v and a built-in 120v inverter

What I'm hoping exists is an adapter that will let me go from the 30amp power down to one of those.

Thoughts?

[Oz and Us]

I'm dry camping at a primitive campground this coming weekend and I need very basic power - for limited light usage in the PUP and for a bipap machine (for sleep apnea) at night.

My battery on the pup was dead when I bought it, but it was never an issue because we always camped with hookups. And, I'm looking to sell the pup soon so I'd rather not invest the $$ in a new battery.

Here's what I have -
 - a pup with a 30am power cord
 - a Dodge Ram w/ 12v and a built-in 120v inverter

What I'm hoping exists is an adapter that will let me go from the 30amp power down to one of those.

Thoughts?

I'm confused.   First, is your cpap machine 120 vac, or 12 vdc, or either?  Are you saying your RAM has a built in inverter that's powered from the truck's 12 vdc electrical system and outputs 120 vac?  If so, what is the rating of this inverter, keeping in mind that a cpap machine can draw a fair amount of power over the course of a night?  Insofar as your trailer's 30 amp main service is concerned, sure you can use a dogbone adpater to convert the plug to a 15 amp U Gnd plug but obviously it's still a 120 vac system and can't be powered directly from any 12 vdc source, IF that's what you're thinking.

[parrothead]

First, if you have electric trailer brakes, you need a working battery on the trailer for the breakaway switch. Second, you can get the adapter but will drain the battery fairly quickly.
 

[Chuck S]

Vehicle inverters really only work well when the vehicle is running.  I doubt you will want to run the truck all night. 

Vehicle starting batteries are designed and constructed for just that purpose.  A couple of seconds cranking and they've done their job for the day.  They are not designed for long term discharge.  Try leaving a dome light on and see how long the battery lasts.

If you want 12v on the camper you need a battery.  If you want to dry camp you need a Big Battery.  No way around this.

-- Chuck

[ependydad]

I'm confused.   First, is your cpap machine 120 vac, or 12 vdc, or either?  Are you saying your RAM has a built in inverter that's powered from the truck's 12 vdc electrical system and outputs 120 vac?  If so, what is the rating of this inverter, keeping in mind that a cpap machine can draw a fair amount of power over the course of a night?  Insofar as your trailer's 30 amp main service is concerned, sure you can use a dogbone adpater to convert the plug to a 15 amp U Gnd plug but obviously it's still a 120 vac system and can't be powered directly from any 12 vdc source, IF that's what you're thinking.

Ahh, yes - confusion when I try to talk about electricity! I'm not surprised.

The CPAP machine is 120 vac.

Yes, the truck has a built-in inverter powered from the truck's 12 vdc system and outputs 120 vac. I'm not finding anything more than "115-Volt Auxiliary Power Outlet" from the specs. The user manual is on a CD, so it's not even a book. I'll look up what it actually is.

I'm thinking of the dogbone you linked to, plugged directly into this outlet in the truck (powered by the built-in inverter).

[ependydad]

If you want 12v on the camper you need a battery.  If you want to dry camp you need a Big Battery.  No way around this.

Sigh, and I know you're right. I'm just trying to eek out one last trip with the pup.

[Cheyenne06]

Related to this, be sure and read your bipap manual as many/most seem to say "do not run this of a modified sine wave inverter, it should only be used with a true sine wave" or something to that effect.  All but the most expensive inverters you would plug into your TV are modified sine wave. There are some model CPAPS that are OK with a modified sine wave and say so.

[ependydad]

Related to this, be sure and read your bipap manual as many/most seem to say "do not run this of a modified sine wave inverter, it should only be used with a true sine wave" or something to that effect.  All but the most expensive inverters you would plug into your TV are modified sine wave. There are some model CPAPS that are OK with a modified sine wave and say so.

I'll double-check that, but I think that has to do with the humidifier (which is also where a majority of the power consumption comes from) than the actual bipap/cpap machine. But, I'll check.

[Recumbentman]

I'm looking to sell the pup soon so I'd rather not invest the $$ in a new battery.

If you are going to want top dollar for you pu when you sell it, you are going to have to have everything working 
so sooner or later you are going to have to buy a battery 

[ependydad]

I'm looking to sell the pup soon so I'd rather not invest the $$ in a new battery.

If you are going to want top dollar for you pu when you sell it, you are going to have to have everything working 
so sooner or later you are going to have to buy a battery 

I'm conveniently ignoring that fact!

Problem is - if I buy the battery, don't I also need to buy the fancy 3-stage trickle charger? And then... you know, these things grow in my world to be real projects.

Serious question (and possibly a dumb on) - if I go to Wally World or Costco and buy a deep cycle battery, will it come fully charged? Or does it need some interaction before it works?

[beemerphile1]

Do not try to plug the trailer directly into the inverter with an adapter.  If anything plug the cpap directly into the inverter and use flashlights.

The factory inverter probably is only 80 to 100 watts.  It won't power much and you will need to keep the engine idling all night.  Just for giggles consider that 30 amp equals 3,600 watts.

All in all probably not a great idea and the results will be unsatisfactory.

[beemerphile1]

Problem is - if I buy the battery, don't I also need to buy the fancy 3-stage trickle charger?

Doesn't your pup already have a converter/charger?

if I go to Wally World or Costco and buy a deep cycle battery, will it come fully charged? Or does it need some interaction before it works?

Mostly charged and will work but should be topped off before use.  Using the battery with only the factory dry charge will shorten the life of the battery.

[ependydad]

Problem is - if I buy the battery, don't I also need to buy the fancy 3-stage trickle charger?

Doesn't your pup already have a converter/charger?

To be honest- I just don't know. (Obviously, I'm kind of an idiot with this stuff!) The previous owner (a know-it-all sort) said "it should charge while you drive", but it was dead when I bought it and they had been using it. SO... not sure.

And, I'm not even sure how to find out. Thoughts?

[ependydad]

Problem is - if I buy the battery, don't I also need to buy the fancy 3-stage trickle charger?

Doesn't your pup already have a converter/charger?

To be honest- I just don't know. (Obviously, I'm kind of an idiot with this stuff!) The previous owner (a know-it-all sort) said "it should charge while you drive", but it was dead when I bought it and they had been using it. SO... not sure.

And, I'm not even sure how to find out. Thoughts?

Ok, in a rare move - I tried to RTFM. Here's one that I found online a while back (from somewhere and just uploaded to my server):
2001_Niagara_CamperOwnersManual.pdf (edit: corrected file name - it's a 2001 manual, not 2011)

It's kind of hard to read, but around page 52 it appears to read "All converters contain a battery charge unit within the converter."

SO- does that answer my question?

I know that the truck can power the camper. We've done that in the driveway when getting ready for a trip; but, is that enough for it to actually charge the battery at all?

AND... is a 2-hour drive to the campground enough to top it off?

[ependydad]

I believe this is the built-in inverter's specs:
"A 115 Volt (150 Watts Maximum) outlet is located on the center stack of the instrument panel, to the right of the radio."

From here:
Random online source for 2012 Ram 3500 user manual