Electrical Comments/Advice Requested

[dog_and_ape]

Currently sealing the sheet metal on the floor of my '2007 Chevy Midbus 6-Window and trying to hammer out the details of my electrical scheme. Looking for any tips and tricks related to making this system more efficient and safer before I actually start installing anything and pay an electrician to take a look. Referencing the two attachments; first one (Electrical) focuses on panel to inverter pathways and the second on AC and secondary power sources.


I'll be relying mainly on solar with three LG NeON2 335W panels with a Vmpp of 34.1V and Impp of 9.83A. I'll be feeding those into a 100A fused combiner box with 10AWG. I'll bring 10AWG down to a Victron 150V/100A MPPT.


I'll drop down to 6AWG to bring power from the controller to the busbars and put a 100A switchable fuse and a disconnect in- though maybe I should be putting in a bigger fuse now that I think about it if my charger is rated at 100A?


Batteries: four 100Ah Battle Born 12v LiFePO4 for 100Ahs. Gonna wire together with 2/0 welder wire and tin plated lugs like in the attached screenshot. Positive lead from the bank will hit a disconnect before hitting the positive bus bar and the negative lead will hit Victon's 500A shunt with battery monitor.


DC loads are coming off the bus bars into distribution boxes.



I've got the AIMS 3000w Inverter/1200w Charger that will be wired to the bus bars with 2/0 and a 250A fuse on the positive line. The inverter also then functions as a 100A battery charger when I'm plugged into shore power.


Now switching to the other attachment (AC Systems) this is where things get weird. The little table shows the use cases I'm trying to solve for.
Without going into my bus life philosophy, I'm attempting to be able to pull energy any place i can possibly have the opportunity to while maximizing my ability to live in most climate spaces. I'm spending a considerable portion of my budget and energy focusing on insulation so that I get the most out of passive climate measures and rarely have to rely on active ones. In my mind, utilizing separate 15a and 30a shore powers circuits achieved this.



The 15A is dedicated to servicing the charge function of the inverter, only. Its going to come in through a 30A load center to serve as a disconnect with a hardwired Eaton whole-home surge protector. As long as I'm not inverting, the 15A will be able to charge the batteries and the internal transfer switch of the inverter will automatically switch from inverting to charging if I'm plugged in and my batteries get too low (low sun situation).


Independently, I'd like a 30A service, then, to just focus on the AC systems inside. The 30A is going to come through a Progressive Industries EMS hardwired surge protector and then into a 30A load center. The intent is to simply use this breaker as a disconnect because I'll have a load center downstream and I have the EMS surge protector upstream. Or do I need to upgrade to 40A minimums here as well?


The next step is a Surge Guard automatic transfer switch. The primary power in the switch will be from the inverter. At 3000w (9000w surge for up to 20 sec) the inverter will push up to 25A through my cabin. However, when I plug into 30A, shore power, the ATS will jump and I'll get the full 30A to my AC system.


I have two main loads. The first is my hot water heater which has a max draw of 12A if I'm running solely electric. However, its duel-fuel propane and I can easily flip it over during operation to conserve that and utilize another high draw appliance in the kitchen (rice cooker). My electric cooler will be tied into the 12v system but I'll have an outlet back there so that I have the ability to plug in if needed. Max draw of .63A here though so not a biggy.


On the other side, my main load is an 1800W induction cook top burner. Its highest output draws the full 15A. I have a wood stove so anytime I'm burning wood, I'll be heating water and cooking there. Except for the main loads- the other outlets are simply "in cases" or "nice to haves" so I'll be able to easily ensure im not exceeding loads. Additionally, I have a couple of mini inverters and am installing 12v outlets and usb ports all over so that I don't have to fire up the big inverter for small tasks.


Using 13/3 for all the AC and generally sized up for all the DC wire as well. My combiner box, MPPT, batteries, bus bars and inverter will all be colocated keeping the lengths and voltage drops very very small.


Thanks in advance

[dzl_]

Looks like a well thought through system,



The only things that jump out at me on the DC side are that you may want a main battery bank fuse close to the battery (MRBF or Class T would be ideal) and that your diagram doesn't show any equipment grounding on the DC side. It is almost certain that your AIMS inverter will have a place on the chassis to connect a ground wire, PV panels are also usually grounded, and your solar charge controller can optionally be grounded as well, not sure about the combiner box. 100A fuse on the solar charge controller circuit is probably fine, your panels won't produce the full 100A, but 125A would work too.

[dzl_]

And one thought on the AC side,

If you plan to stay at campground with hookups, RV parks etc, will you be able to use both shore power connections without having to pay double? Or is that not how that works? (I have no idea, I've never tried-- just a thought)

[JDSquared]

Thanks for posting this. I can't offer advice but it is so similar to what I have in my head and trying to get down on paper for my own bus. Going to use this as a guide.

[JDOnTheGo]

The first page looks pretty good. I would add some type of disconnect (DC breaker) at the charge controller for the solar array input. Being able to disconnect the array makes maintenance much easier.

The second page... Rather complicated. I get the goal but I don't think it is worth all the complexity and the always hot 15 amp shore connection is dangerous. You also lose the ability to charge from 30 amp shore power. A dogbone connector allows connecting to either 15 or 30 amp shore connection and avoids whatever problems could occur with a 15 and 30 amp connection that are out of phase. I'm not certain but I believe that will allow the smoke to escape from something (maybe not with the inline protection... I dunno...). When connected to a 30 amp pedestal, all you are going to get is 30 amps, regardless of it having both a 15 and 30 amp socket.

I suggest eliminating the 15 amp shore power connector. That will make it safer, simpler, less costly, and easier to manage (switches instead of cords).

[JDOnTheGo]

Originally Posted by dzl_

If you plan to stay at campground with hookups, RV parks etc, will you be able to use both shore power connections without having to pay double?

They don't care. You have a pedestal at your spot, you can plug as much as you like into it. However; that pedestal is limited by it's input. In most cases, a 30 amp pedestal is a max of 30 amps (not 30 amps plus 15 amps). Of course, that all depends on how it is wired.

[Danjo]

First I would like to compliment you on your thoroughness and attention to detail. Very impressive.

From a use case perspective though, I’m not seeing how you can function untethered. Why be all-electric? That’s not to say there’s anything wrong with that of course, but have you done an energy budget for being untethered?

I am in the process of converting a 5 window Thomas and it’s been a challenge to find a place for everything. I feel like the infrastructure is overrunning my ability to store things. This is probably due in part to my desire to not blank any windows. So I’m really interested to see how you fit everything. Compared to a lot of short bus builds, I thought I was trying to put 10 pounds in a 5 pound bag, but I think you might be doing more.

On the engineering side of things, I think your cooktop is exceeding the recommended ampacity of the circuit and your water heater is just at the max.

[dog_and_ape]

Originally Posted by dzl_

Looks like a well thought through system,



The only things that jump out at me on the DC side are that you may want a main battery bank fuse close to the battery (MRBF or Class T would be ideal) and that your diagram doesn't show any equipment grounding on the DC side. It is almost certain that your AIMS inverter will have a place on the chassis to connect a ground wire, PV panels are also usually grounded, and your solar charge controller can optionally be grounded as well, not sure about the combiner box. 100A fuse on the solar charge controller circuit is probably fine, your panels won't produce the full 100A, but 125A would work too.

Thanks! It sounds like a Class T right next to the battery terminal is the way to go. Grounding and Neutral bonding is the next task to unravel here. My PV panels and inverter both have grounding lugs as well as my AC load centers. The original bus 12v is bonded to both the frame and the chassis. I'm also have a 3600W generator for emergencies that I'll have to take into account for that scheme, I'm assuming. Any advice/experience on getting good separate grounds and neutral bonds?

[dog_and_ape]

Originally Posted by JDSquared

Thanks for posting this. I can't offer advice but it is so similar to what I have in my head and trying to get down on paper for my own bus. Going to use this as a guide.

No problem! That's exactly where I was two years ago when I started thinking about mine.

[dog_and_ape]

Originally Posted by JDOnTheGo

The first page looks pretty good. I would add some type of disconnect (DC breaker) at the charge controller for the solar array input. Being able to disconnect the array makes maintenance much easier.

The second page... Rather complicated. I get the goal but I don't think it is worth all the complexity and the always hot 15 amp shore connection is dangerous. You also lose the ability to charge from 30 amp shore power. A dogbone connector allows connecting to either 15 or 30 amp shore connection and avoids whatever problems could occur with a 15 and 30 amp connection that are out of phase. I'm not certain but I believe that will allow the smoke to escape from something (maybe not with the inline protection... I dunno...). When connected to a 30 amp pedestal, all you are going to get is 30 amps, regardless of it having both a 15 and 30 amp socket.

I suggest eliminating the 15 amp shore power connector. That will make it safer, simpler, less costly, and easier to manage (switches instead of cords).

The Solar combiner box is switchable so I'll be able to disconnect the PV completely from my system as it comes into the cabin.


Why is an "always hot" 15a dangerous and why wouldn't it be any more dangerous than having an "always hot 30A or 50A plugged into your rig? The inverter cant charge and invert simultaneously so you can't overload a pathway without frying the whole unit and I have two stages of over current protection on both circuits before they enter any equipment or make it through a firewall.






"whatever problems could occur with a 15 and 30 amp connection that are out of phase"


If you could explain how you think these two separate and isolated circuits would do this?

[dog_and_ape]

Originally Posted by Danjo

First I would like to compliment you on your thoroughness and attention to detail. Very impressive.

From a use case perspective though, I’m not seeing how you can function untethered. Why be all-electric? That’s not to say there’s anything wrong with that of course, but have you done an energy budget for being untethered?

I am in the process of converting a 5 window Thomas and it’s been a challenge to find a place for everything. I feel like the infrastructure is overrunning my ability to store things. This is probably due in part to my desire to not blank any windows. So I’m really interested to see how you fit everything. Compared to a lot of short bus builds, I thought I was trying to put 10 pounds in a 5 pound bag, but I think you might be doing more.

On the engineering side of things, I think your cooktop is exceeding the recommended ampacity of the circuit and your water heater is just at the max.

I didn't say I was all electric, actually. 1000W of solar and 400Ah of battery and you think I need to have an umbilical cord 100% of the time?

[JDOnTheGo]

Originally Posted by dog_and_ape

"whatever problems could occur with a 15 and 30 amp connection that are out of phase" If you could explain how you think these two separate and isolated circuits would do this?

Ahh.. gotcha - I was seeing that black then yellow line (in/out of the inverter)as a continuous line. Apologies. Disregard my always hot comment please.

With that in mind, I see even less value in having two shore power connections. It just needlessly adds hardware. Or, I'm completely missing the design goal.

[JDOnTheGo]

Originally Posted by dog_and_ape

"whatever problems could occur with a 15 and 30 amp connection that are out of phase"

If you could explain how you think these two separate and isolated circuits would do this?

The inverter and 30 amp shore power are combined at the 30 amp transfer switch. If you ever forget to power off the inverter before plugging into shore power... Hmmm... I would not expect good things. I have never actually done that so can't say for certain - maybe the inverter has some sort of internal detection/protection.

What is the design goal that necessitates two shore power connections??

[dog_and_ape]

Originally Posted by JDOnTheGo

The inverter and 30 amp shore power are combined at the 30 amp transfer switch. If you ever forget to power off the inverter before plugging into shore power... Hmmm... I would not expect good things. I have never actually done that so can't say for certain - maybe the inverter has some sort of internal detection/protection.

What is the design goal that necessitates two shore power connections??

Why would I need to power off the inverter before turning on shore power? Are you familiar with the AIMS inverter?

[dog_and_ape]

Originally Posted by JDOnTheGo

Ahh.. gotcha - I was seeing that black then yellow line (in/out of the inverter)as a continuous line. Apologies. Disregard my always hot comment please.

With that in mind, I see even less value in having two shore power connections. It just needlessly adds hardware. Or, I'm completely missing the design goal.

30A shore power is designed primarily to be connected to 3600w generator in "emergency". If I only had a 30A connection and was in a low light environment where I needed to charge quickly to get back on the road, I would have no electrical systems while I'm charging.


Will I ever plug into an RV pedestal ... maybe. Will I ever voluntarily park myself where I can talk to my neighbors through a window ... no.

[somewhereinusa]

Just a casual observation, I think you are over engineering and adding things that aren't really necessary.
If you wire for 30A and use a 15A adapter to plug in to something everything will work. If you happen to draw more than the external source will handle it's breaker will pop.
I am wired for 50A and regularly plug into 15 and 30 amp circuits. If you watch your usage it's quite manageable I did it that way for a few years. I nowhave a Victron hybrid inverter/charger. I can tell it that I only have 15A, or whatever, available. If I go over that say, microwave and AC at the same time it automatically draws what ever it needs from the battery bank to make up the difference. When amp draw goes under that setting it goes back to charging the batteries.

Magnum also offers a hybrid inverter/charger I don't know if others do. Also by using an inverter charger you get a built in automatic transfer switch. The Victron also has a separate circuit to charge/maintain your start batteries.

[JDOnTheGo]

Originally Posted by dog_and_ape

Are you familiar with the AIMS inverter?

No, please enlighten us as to what happens when you feed in opposite polarity 120VAC power.

[dog_and_ape]

Originally Posted by JDOnTheGo

No, please enlighten us as to what happens when you feed in opposite polarity 120VAC power.

lol. So you you don't know how they work. If the switchgear of an inverter/charger couldn't handle reverse polarity, it would be a pretty poor switchgear for its function, no?