Questions on "Easy" Inverter Installation

ReenieG · July 18

I am in the process of adding an inverter to my new dual battery setup in my new center tub. I do not want to move the batteries inside like many do and I do not want to wire the inverter into the WFCO electrical system. My discussion started HERE, but since I wanted to get feedback specifically on my questions, I started this new post.

First off, the "easy" installation will be to plug in my inverter into the 30amp outlet after isolating my WFCO converter to a dedicated 15amp plug to turn off while using the inverter.

Here are my questions and I would appreciate any input from your experience you have on this. If you comment and have diagrams or pics, please share.

Inverters:

1. What size inverter would allow me to run my "larger" appliances? Mostly all of them, including the new Midea AC and a portable microwave are 700 watts. If I switch out my Bella K-cup coffeemaker that is 700w for a Keurig, that would be 1500w I believe. I understand that I would only be able to run one large appliance at a time and maybe for a short amount of time. I believe an inverter would also give me the option of using my 3-way on electric since the amp draw is much less than on battery.

2. I'm thinking a 2000w inverter would be best for me. Looking at THIS one, which I like for the ratings and reviews and I currently use other VEVOR products which work well.

3. The other option would be a BougeRV inverter which also has a good rating and reviews. This one also has the ability to hardwire it besides plugging in. I don't think I need that capability atm but if I moved it, I might.

4. What size wires would be best for wiring from the batteries to the inverter? I understand that would depend on the loads, but if I have a 2000w inverter and wanted to be able to safely use it, what size wires? I'm hoping to keep the run short, which brings up my next question.

5. Other than installing the inverter in the tub with the batteries has anyone installed an inverter somewhere else with their batteries in the tub? I'm not going to bring my batteries inside although I know many people do.

Bus bars:

1 Do I need to use bus bars? I don't think so but if someone can tell me I do and why, then ok.

Fuse size:

1. I'm reading all over the place to use a T-fuse? Why and what size fuse do I need?

I think those are my main questions, for now, lol. If I think of anything else, I will add another post to this discussion. Thank you all in advance. I can't wait to read your suggestions and comments!

Yoshi_TAB · July 18

Hi,

Here are my thoughts from my experience installing a 2000W inverter when I had my 320.

1. A 2000W inverter seems to meet your needs.

2. When I ran the calculations to determine fuse and wire size, I came up with 2/0 AWG with a 225 amp fuse. Below is a screen shot from my calcs. Also below is a link to a site that explains how to do the calcs.

3. My inverter was about 5 feet from the batteries.

4. Busbars are recommeded to minimize or reduce the number of connections on the battery (or other devices). When you stack ring terminals on batteries, especially of different sizes, you have the potential for poor contact area resulting in heat build up or voltage drop. I would recommend them.

5. I used a Class T fuse based on recommendations from other forums and RV electrical sites I reviewed. Although not required, they are considered the "gold standard" for fuse and line protection because of their fast response time on higher capacity circuits. The design of the fuse and holder also leads to safer situations post "blow" (i.e reduce arcing potential). The con is cost and a bit bulkier to find a mounting location.

6. I would recommend a ON/OFF switch to be able to isolate the inverter circuit from the other battery circuit if you need to work on the inverter circuit.

7. I would sketch out a proposed layout and folks here can provide feedback. Here is mine but start at the end of the thread to see it. I had a transfer switch, so it was a bit different.  2021 320 Lithium and Inverter Install (Complete) There were some minor changes during the install, but nothing major.

8. Recommend to get name brand fuses, wiring and connectors vs knock offs. IMO don't want to skimp in this area.

9. Here is a link to a source on how to calculate fuse and wire size.  Calculating Inverter DC Wire & Fuse Size | DIY Solar Power Forum

10. Make sure all your connections are tight! The first time I checked, my wires they got warm because I did not correctly torque connections. You can buy an inexpensive heat gun to check. I boiled water in the microwave and checked each connection with the heat gun. I was very surprise of the heat build up the first time I ran the system.

11. Have fun !

Image: https://us.v-cdn.net/5021717/uploads/editor/08/7314yr8cqp8s.jpg

ReenieG · July 18

@Yoshi_TAB very nice response! I'll check out your links.

You say your inverter was 5ft from the batteries. Were the batteries in the tub or inside? And where was the inverter located? I just looked at your pics and see you did move your batteries and inverter under the seat!

Since I'm not planning on bringing batteries inside, I'm going to see if there's any way to either mount the inverter in the tub close to the batteries or run a wire through the front wall inside the trailer for the inverter.

You went with a 225a fuse vs increasing it to 250a size. Is there a reason you sized down vs up?

As for bus bars, I may not need them with my "simple" install. I'm not using many of the components and wiring you have added. I'd like to keep this as simple as possible but, well, we'll see... lol

Yoshi_TAB · July 18

Hi @ReenieG ,

Yes, my batteries were inside the TAB. That move was part of an entire upgrade along with the inverter install.

There is a relatively easy way to move the batteries inside without routing wires from the outside to inside (i.e no hole cutting)

If you look at the link to my install, you will see pictures (go to the end of the thread). I had a '21 320 and placed two batteries under the passenger side seat (in front of underbunk AC) and the inverter went under the driver side seat (where the WFCO is located)

Yoshi_TAB · July 18

Hi @ReenieG,

You are correct...I did have a 250A fuse. I looked back at my order receipts. I forgot to update my drawing and my memory failed me. I was working with someone on the DIY solar site and I wasn't sure and he recommend to use the 250A.

To bring your batteries inside, there is a #6 battery wire coming from your WFCO. This is the very wire the runs directly outside to your battery tub (via the trailer junction box). You would just splice into this inside wire coming from your WFCO. It is essentially using the same wire the routes outside. You just have to still power that wire as it powers your emergency trailer brakes.

Image: https://us.v-cdn.net/5021717/uploads/editor/dd/8gjgfpf8896h.jpg

ReenieG · July 18

@Yoshi_TAB love the diagrams! I'll consider that splice, but I really want to leave the batteries outside in my tub. I just ordered a new box for them and it arrives tomorrow. I'll have plenty of room for the 2 100ah minis I have. They are group 24 and will fit nicely inside this box. I will have to figure out if I want to bring my inverter inside the trailer. I will add some pics and diagrams once I complete them, but since I'm not adding my wiring into the WFCO (only isolating the converter to it's own 15amp breaker) if I can protect and secure the inverter into the tub, it would make more sense since it will be plugged into my 30amp shore power outlet when being used.

Here's an example of one of the YouTubers that did this "simple" inverter setup. They used a larger fuse and they have a 50amp system, but the idea is the same. They also have a little different battery bank and a shunt installed which I won't have. My batteries are blue tooth and so is my mppt solar controller so I can monitor that way.

Image: https://us.v-cdn.net/5021717/uploads/editor/j4/x7af3ws9kznz.jpg

So, the next question(s) are: on the T fuse holder, there are 150v size and 250v size, which I believe is the max voltage and if I understand this correctly, either will do? You can see HERE there are both options. Do you know which one you used and why?

Yoshi_TAB · July 18

Hi,

This is what I ordered. Rated for 225A-400A. Blue Sea is more money but very high quality. Used in many marine/solar applications. I also used Blue Sea fuse (and 1 spare).

Amazon.com: Blue Sea Systems Class T Fuse Blocks : Industrial & Scientific

Blue Sea Systems - Relentlessly Reliable™

Just wanted to pass on how to move the batteries inside w/o cutting holes as that often stops people. Keeping it simple is a great approach. I wanted the extra space in the front tub so that was my main driver for moving the batteries.

Once I had my components layed out, I used string to determine cable length. I bought cable from Windy Nation with the lugs already crimped on. They have an amazon site which makes returning them easy if you need them longer or shorter. Lugs come in two different diameters depending on the device you are connecting.

ReenieG · July 18

@Yoshi_TAB thank you for your input! I will probably be baaack! Haha

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