Extra Batteries and Inverters

[Supercharged111]

I saw this article and thought it was pretty neat. Since I want to add aux tanks in front of the rear fenders, I like the lift off wooden box that sits on top of the fender the best.

https://www.truckcampermagazine.com/camper-mods/projects/5-extra-battery-storage-areas-for-truck-campers/

Looks easy enough to build and wire. I wonder if anyone else has gotten more creative than what's in the article? The point of this and the inverter would be quieter boondocking, I hate to have to fire the generator to make a pot of coffee or run the microwave.

https://www.truckcampermagazine.com/camper-mods/projects/5-extra-battery-storage-areas-for-truck-campers/


I'm also curious about wiring an inverter. Wiring doesn't scare me one bit, I've done a few motor swaps in my day and am no stranger to a soldering gun. The camper/house wiring in comparison seems even simpler. I'm wondering if there's a junction box somewhere that I'm supposed to get into to tie the inverter in? Do you use a contactor of some sort to switch from shore power to the inverter?

Yes, I need to up my solar game as well, but don't plan to get into that in this thread. I had my questions answered there in a thread I posted previously.

[Virgil_Diesel]

Here what Idid to bypass the converter when using Inverter. Follow the link below.
Cam Switch

[Kayteg1]

Supercharged111 wrote:

Duh! I forgot that Torklift makes mounts like this. I could easily make my own and hang it off the frame in front of the rear wheels. Out of the way and I could have a relay in the mix to divorce it from the truck too. Would plug into the camper the same as something that lived in the back of the truck.

I just went via torklift site and the only thing they do is hanging bracket with standard battery box.
So you need 1 for each battery.
At $140 a pop, that can get pricey and I can't imagine this thing lasting.

[Supercharged111]

Hemi Joel wrote:
Are you using a relay or something to disconnect the converter when the inverter is on? How about the air conditioner? Are you disconnecting that when running the inverter, or do you have a huge inverter and battery bank to run the AC?

I don't think this was directed at me, but I had read about killing the converter with the inverter running. Seems to me that a simple trigger wire from the output of the first transfer switch could feed a relay to keep the inverter on, then when the second switch hits it'd lose that input and stop charging. As for the AC, my intent was to just leave that be. I plan to have 4 batteries total which probably wouldn't run the AC for very long, but it's as simple as just turning that off. My challenge now is to find a 3000W pure sine wave inverter that can be hardwired, all I'm seeing so far is inverters with ~4 outlets on the front panel.

[Supercharged111]

Kayteg1 wrote:
I wonder is somebody tried to install batteries under truck bed? There should be enough space and that would not only be more convenient, but also lowers COG.
I found this one on ebay designated for Sprinter vans.
For transfer switch, I am making conversion with no generator and I made inverter the default.
When transfer switch is activated, it will draw some power and you don't want it while using batteries.
Still have to remember to turn converter breaker off/on.

Duh! I forgot that Torklift makes mounts like this. I could easily make my own and hang it off the frame in front of the rear wheels. Out of the way and I could have a relay in the mix to divorce it from the truck too. Would plug into the camper the same as something that lived in the back of the truck.

[Supercharged111]

srschang wrote:
I just installed a second transfer switch in my new Northstar 12 STC a few weeks ago. The camper came with a transfer switch installed to switch between shore power and generator power. If you are connected to shore power, and start the generator, after 30 seconds or so the switch disconnects the shore power and almost instantly connects the generator power. I added a second transfer switch that switches between the output from the first transfer switch (either shore power or generator power) and my inverter. The only tricky part to a transfer switch is choosing the priority for the switch. There are two input connections to a transfer switch, usually called shore and generator. The generator input is the priority, if both shore and generator are connected, the switch will always shut off shore and connect the generator. If the generator is turned off, the switch will switch back to shore.

I took the output from the first transfer switch, and connected it to the "Generator" input of my second transfer switch. I then connected my inverter to the "Shore" input. Then I connected the output to the 110V distribution panel in the power center of the camper. So now, if I'm running on the inverter and plug into shore power, the second switch disconnects from the inverter and connects to the shore power. If I'm running on the inverter and have no shore power, then start the generator, the second switch disconnects from the inverter and connects the generator.

So the priority for 110V in my camper is lowest priority inverter, mid priority shore power, highest priority generator. You can set the priority however you want, just have to connect each power source to the appropriate priority of the transfer switch. As I said, the transfer switch two input connections are usually labeled "Shore" and "Generator", the "Generator" input has priority. If there is power coming into the "Shore" input and the "Generator" input at the same time, the transfer switch turns on the generator input and shuts off the shore input.

It sounds more confusing than it really is. But if I can figure it out, anybody can.

Good, this is how I'd envisioned the switch worked and needed to be wired, glad to hear it confirmed and now I anticipate how the thing will be labelled. That's exactly how I want mine to be.

[Kayteg1]

I was thinking about adding relay to converter circuit and hook it up to transfer switch, so it would be open when on battery power and close when shore power is on.
But that makes lot of additional wiring and as said above >>> if you forget to flip the breaker when dry-camping you are a dummy.

[srschang]

Added a small single breaker box and moved the converter 110v supply from the power center to the breaker box. Then wire the breaker box to shore power before the transfer switch so it will only run from shore power.

Didn't take the time to move the A/C ahead of the second transfer switch. Figured if I turn on the A/C while running on the inverter and run my batteries down, I'm a dummy. Best way would be to also move the A/C out of the power center and into it's own breaker box (or with the converter in a small box that will handle more than 1 breaker) ahead of the transfer switch.

[Hemi_Joel]

Are you using a relay or something to disconnect the converter when the inverter is on? How about the air conditioner? Are you disconnecting that when running the inverter, or do you have a huge inverter and battery bank to run the AC?

[Kayteg1]

I wonder is somebody tried to install batteries under truck bed? There should be enough space and that would not only be more convenient, but also lowers COG.
I found this one on ebay designated for Sprinter vans.
For transfer switch, I am making conversion with no generator and I made inverter the default.
When transfer switch is activated, it will draw some power and you don't want it while using batteries.
Still have to remember to turn converter breaker off/on.

[srschang]

I just installed a second transfer switch in my new Northstar 12 STC a few weeks ago. The camper came with a transfer switch installed to switch between shore power and generator power. If you are connected to shore power, and start the generator, after 30 seconds or so the switch disconnects the shore power and almost instantly connects the generator power. I added a second transfer switch that switches between the output from the first transfer switch (either shore power or generator power) and my inverter. The only tricky part to a transfer switch is choosing the priority for the switch. There are two input connections to a transfer switch, usually called shore and generator. The generator input is the priority, if both shore and generator are connected, the switch will always shut off shore and connect the generator. If the generator is turned off, the switch will switch back to shore.

I took the output from the first transfer switch, and connected it to the "Generator" input of my second transfer switch. I then connected my inverter to the "Shore" input. Then I connected the output to the 110V distribution panel in the power center of the camper. So now, if I'm running on the inverter and plug into shore power, the second switch disconnects from the inverter and connects to the shore power. If I'm running on the inverter and have no shore power, then start the generator, the second switch disconnects from the inverter and connects the generator.

So the priority for 110V in my camper is lowest priority inverter, mid priority shore power, highest priority generator. You can set the priority however you want, just have to connect each power source to the appropriate priority of the transfer switch. As I said, the transfer switch two input connections are usually labeled "Shore" and "Generator", the "Generator" input has priority. If there is power coming into the "Shore" input and the "Generator" input at the same time, the transfer switch turns on the generator input and shuts off the shore input.

It sounds more confusing than it really is. But if I can figure it out, anybody can.

[Supercharged111]

That was kinda generic unless I missed something, I just need to hunt a little more for a diagram on how the transfer switch does it's thing. And get my hands on the schematic for my camper. I think I have those.

[Hemi_Joel]

https://www.doityourselfrv.com/rv-inverter-install-diy/

THis should be helpful

[Supercharged111]

Seems something like this ought to work, I'd just put it downstream of the transfer switch I must already have that switches from shore power to generator.

https://www.campingworld.com/trc-30-amp-automatic-transfer-switch-75000.html?gclsrc=aw.ds&&gclid=Cj0KCQjwmpb0BRCBARIsAG7y4zarJ02Tr9emyGwR5BU4T4pVhOl0vwp6nioybc4WFxVGu8uRpf6inc8aArNGEALw_wcB

I'm guessing one of the 2 inputs is considered the priority input and will favor it over the backup source?

[Lwiddis]

“The camper/house wiring in comparison seems even simpler.”

Provided you use an adequate gauge wire, yes.

[Hemi_Joel]

Your connection of the 110v feed from the inverter needs to be isolated from shore power and generator power in a 100% failsafe method. The easy way is to run some outlets (Additional new or re-wired existing) that are dedicated to the inverter. When the inverter is in use, plug into them. When not, plug into the others.
Or else you can do it with an additional automatic transfer switch. There are articles online how to rig up automatic transfer switches in pairs to isolate and prioritize the power source that is feeding the coach wiring. Shore, gen, or inverter.