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Adding Inverter for dry camping

jcarlilesiu
Explorer
Explorer
I would like to add an additional battery (have one group 27 now), possibly a solar charging system and an inverter.

I hate that the 120V outlets don't work on battery power. Seems crazy you can't charge a cell phone.

Anyway, I would like to an an inverter. My goal would be to wire it into the system with an automatic transfer switch for shore power/battery power.

Seems awfully involved.

Is the better option adding an inverter with a dedicated female 30 amp outlet on the side of the rv near the front where the batteries are, and simply plug the shore power cable into the inverter when needed?

Seems easy enough, but not "clean". I would really rather add an inverter and transfer switch. Has anybody one that that can explain the process? Does the converter need to stay? Can it go? If the converter is removed, how do the 12V outlets and lights and water pump run? Will they run off of battery power without the converter when on shore power?

Im confused about that one aspect.
86 REPLIES 86

BFL13
Explorer II
Explorer II
jcarlilesiu wrote:
Snowman9000 wrote:
The maker doesn't care about charging, inverters, solar, etc. They build these things optimized to run on shore power. That's why your converter is at the opposite end from the batteries. Without re-reading, I think you said you have room in the front of the rig to mount a converter or inverter-charger. That's where you should put it. You already have DC cables running from the front to the back to serve the existing converter and fuse box. You will re-use those to supply the fuse box, which will stay where it is.

Currently you have: Batts=============Converter & Fuses===Loads
After you re-do: Batts=Converter===================Fuses===Loads
IIRC someone already said, it's no problem to run 120v wiring the length of the trailer. That's correct. Mount the inverter by the batts, and run the 120 to wherever you need to.


That makes sense.

One question. My shore power cable is on the back near the converter. Wouldn't that have to be extended to the new converter location?


The Converter is the gizmo in the Power Centre that makes 12v from 120v. It can be removed from the power centre and put somewhere else. The power centre would still have the 120v input where you shore cord is terminated, the 120v circuit breakers, and the 12v fuse panel.

A converter mounted away from the power centre is called a "deck mount" and has a full casing (chassis) and its chassis must be grounded to the RV's frame. The converter in the power centre location has a partial chassis grounded by touching the rest of the power centre's chassis which is grounded to the frame, so if you move it to up front you need to make a cover for it and ground it.

One wrinkle is that some converters like the 7355 have their reverse polarity fuses on the fuse panel, while some have them on the converter's own chassis. One of the PD converters has its Charge Wizard button on the fuse panel ISTR, so it would also be hard to relocate.

You can add a deck mount up front and leave the existing converter in with the power centre. The deck mount one up front is on the battery and the battery has wires going back to the 12v fuse panel already, so you don't need to wire that front converter to the fuse panel.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

pianotuna
Nomad II
Nomad II
Hi burning,

While it is true you can't do 500 watts from a standard cigarette lighter, the two in my "house" are fused at 30 amps. I routinely use a 400 watt inverter with mine. So far no fuses have blown. I use it to power my laptop, and a heating pad.

I think that one of the comparisons is the size of the capacitors in a 100 watt vs a 500 watt. That allows more head room for a surge situation.

It also depends on the inverter maker's rating system. Many times they quote the surge value rather than continuous--so a 500 watt might well only be capable of 250 watts of stead draw.


burningman wrote:
Golden_HVAC wrote:

What I would recommend, and it is very simple is buy a 500 watt inveter that plugs into a cigarette lighter.


Just thought I'd point out something (I'm sure you already know this G_HVAC) about those inverters that plug into a cigarette lighter; 500 watts is impossible because you'd need over 40 amps through that cigarette lighter plug, IF the thing was 100% efficient.

You can only get tiny power from those things.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

burningman
Explorer II
Explorer II
Golden_HVAC wrote:

What I would recommend, and it is very simple is buy a 500 watt inveter that plugs into a cigarette lighter.


Just thought I'd point out something (I'm sure you already know this G_HVAC) about those inverters that plug into a cigarette lighter; 500 watts is impossible because you'd need over 40 amps through that cigarette lighter plug, IF the thing was 100% efficient.

You can only get tiny power from those things.
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jcarlilesiu
Explorer
Explorer
Snowman9000 wrote:
The maker doesn't care about charging, inverters, solar, etc. They build these things optimized to run on shore power. That's why your converter is at the opposite end from the batteries. Without re-reading, I think you said you have room in the front of the rig to mount a converter or inverter-charger. That's where you should put it. You already have DC cables running from the front to the back to serve the existing converter and fuse box. You will re-use those to supply the fuse box, which will stay where it is.

Currently you have: Batts=============Converter & Fuses===Loads
After you re-do: Batts=Converter===================Fuses===Loads
IIRC someone already said, it's no problem to run 120v wiring the length of the trailer. That's correct. Mount the inverter by the batts, and run the 120 to wherever you need to.


That makes sense.

One question. My shore power cable is on the back near the converter. Wouldn't that have to be extended to the new converter location?

pianotuna
Nomad II
Nomad II
Getting 60 amps really only matters to folks who generator charge. Those who are on shore power once a week really don't have the same concerns. Those who have adequate solar systems don't care either. My default mode is to have the converter disconnected.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BFL13
Explorer II
Explorer II
You also need the converter to be at 14.x instead of 13.x to get the amps when charging batteries. My 7355 at 13.8 has very low resistance to the batteries but only does 40 something amps briefly on them before tapering into the 30s and doing some time there before spending longer in the 20s.

However, when not doing batteries, but just running a load, it does 56 amps on the same wiring. Eg, I ran a test when on shore power where the inverter was drawing 90 amps from the batts (minus 90 on Trimetric) and I turned on the converter. Amps on the Trimetric now read minus 34, showing that the converter was supplying 56 amps to the batteries, no tapering.

Batteries are not like "normal" loads. They put up a fight 🙂
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

Salvo
Explorer
Explorer
It depends on the converter. The PD has serious problems and will never output 60A. Other converters like Iota with IQ4 and I believe Powermax will supply rated current in boost mode.

Padlin
Explorer
Explorer
Salvo, in your example, if you used 4 or 2 awg would you get the full 60A to the batteries, if nothing else were running?
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Salvo
Explorer
Explorer
Everybody knows to install the inverter close to the battery. That's because the inverter won't work when the cable resistance is high. On the other hand, the converter will still work. It's just that the charging rate will be extremely slow. People think their 60A converter will charge the battery at 60A. With factor cabling, it's not unusual to see max current of only 22A!



This converter is only 7 feet from the battery. But it has about 20 feet of 6 awg cable, making charging woefully inadequate for dry camping when charging with generator.

Snowman9000
Explorer
Explorer
The maker doesn't care about charging, inverters, solar, etc. They build these things optimized to run on shore power. That's why your converter is at the opposite end from the batteries. Without re-reading, I think you said you have room in the front of the rig to mount a converter or inverter-charger. That's where you should put it. You already have DC cables running from the front to the back to serve the existing converter and fuse box. You will re-use those to supply the fuse box, which will stay where it is.

Currently you have: Batts=============Converter & Fuses===Loads
After you re-do: Batts=Converter===================Fuses===Loads
IIRC someone already said, it's no problem to run 120v wiring the length of the trailer. That's correct. Mount the inverter by the batts, and run the 120 to wherever you need to.
Currently RV-less but not done yet.

jcarlilesiu
Explorer
Explorer
I really appreciate all the help.

I'm ready to get started!

jcarlilesiu
Explorer
Explorer
Salvo wrote:
Yes it is an issue. Nobody likes listening to generators while dry camping. The longer the converter to battery cable, the longer it takes the charge the battery. This is not insignificant!

Treat the converter like the inverter. Install it as close as possible to the battery.

BTW, 12 feet of 6 awg cable is not good enough. Use 2 awg.

Ron3rd wrote:
jcarlilesiu wrote:
I'm liking the idea of pulling the converter/charger and installing an inverter/charger.

What about my issue with the distance from the batteries to the converter being about 16 feet?


That's not an issue, but we sure to run the proper gauge of wire. The longer the run, the bigger the wire and the greater the $$! I've got about a 12ft run and if I recall I used 6ga.


Understood.

However, starcraft installed the converter 16 feet away from the batteries.

Why would they do this? Not something I'm Gibb to try to fix I don't think.

BFL13
Explorer II
Explorer II
If you will put the inverter up front near the batts, then you can do the same with an inverter/charger. Or you can have a separate inverter and a deck mount converter beside each other up front (sharing their wires to/from battery can be done with that too). No need to yank the existing converter in back. (unless you want to move it up front as the "deck mount"--but then it needs a cover for its innards. Can be done.) It can come in handy as a spare where is.

You don't need to fuss about long 12v wiring so much if the inverter is only 300w or if bigger, if it will only ever carry small wattage loads. That is what smk is trying to say.

The idea to make the set-up "seamless" with a transfer switch is fine, but nothing can be more "elegant" than just plugging the shore power cord in to one of three places manually. (inverter/pedestal/generator) No worries about ever getting 240v and no complicated transfer switch wiring. It is not an awful lot of work to unplug from one place and into another and is not done very often anyway at any one site.

You can also go under the rig with wiring instead of trying to go through inside past doors etc. Just use some drain pipe or garden hose as conduit and strap it up under there.

You don't have to drive yourself crazy with extra work. 🙂
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

Huntindog
Explorer
Explorer
2oldman wrote:
jcarlilesiu wrote:
(converter/panel)That would be the easiest way to get at the house 120V circuit, right?
Maybe.. depends on if 'house' means 'the whole house'

I intercepted my shore cable where it enters the coach and connects to the 30a romex to the panel. That way I didn't have to go digging around in the panel.
In most cases, you need to get at the panel so you can wire it to take the converter out of service when the inverter is supplying the power.
Huntindog
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Huntindog
Explorer
Explorer
pianotuna wrote:
Hi,

If you are going to bother with a transfer switch, I would urge you to go "whole hog" and install a sub panel so that only those devices you wish to power on the inverter will be active.

Otherwise a simple 30 amp female plug will meet the requirements.


Why? He, like I want all of the outlets to work. I understand the limitations. Can't use the AC, microwave, or fridge on AC.. But i's not a big deal. And I like the clock on the microwave, even if I can't cook anything in it. I can still use the kitchen time function... Doing as you suggest would mean resetting the clock all the time, and would cost more as well as being more complicated
Huntindog
100% boondocking
2021 Grand Design Momentum 398M
2 bathrooms, no waiting
104 gal grey, 104 black,158 fresh
FullBodyPaint, 3,8Kaxles, DiscBrakes
17.5LRH commercial tires
1860watts solar,800 AH Battleborn batterys
2020 Silverado HighCountry CC DA 4X4 DRW