50 amp Motorcoach System Design

[ProfessorPeabody]

I recently purchased a 1989 Bluebird Wanderlodge motorcoach. My family and I will be traveling in it full time over the next year (minimum) and would like the option of living "off the grid" when desired.

I respectfully request your assistance in the design!

My first phase of the build will not include PV panels to cut cost.

Below is my "wish list" which I hope will allow several of you to assist me in building this system (and maybe have fun with the challenge!). Please feel free to correct me on any of the statements I've made or provide better alternatives with your opinion/experience.

General Info:

• The coach has an existing electrical system (that I don't fully understand at this point but working on it).
• 50 amp 240VAC shore power capable (which is split into two 120V/50 amp) for a total of 6kw on each leg.
• 15 and 30 amp 120VAC shore power capable.
• 15kw diesel generator that feeds both legs with 120VAC/50+ amps.
• It has an auto-transfer switch (i think) that switches from generator to shore power.
• Generator has an alternator and 12VDC battery (I'll likely keep this system isolated)
• Main engine (Detroit 8v92 diesel) has an alternator and 12VDC battery system. I'll likely keep this system isolated and continue to run the 12VDC components in the coach off these. May add a 12VDC LifePO4 battery at some point.

Goals:

• Off Grid, use the generator at maximum capable power to charge the 48VDC battery. Hopefully only needing to run the generator a few hours a day.
• On Grid, use available power to charge batteries and supply the coach with power and "boost" capabilities (supplement low shore power with battery).
• Driving, use engine alternator to charge 12VDC and 48VDC batteries. (DC to DC charger here? Orion? suggestions?) (battery to battery charger?)
• PV panels on the roof in the future, but not yet.

The batteries:

• I believe I'd like a 48V system (keep volts high and amps low=better)
• I believe I'll build my own from eve LF280k cells
• I believe a minimum of 14kwh battery (16 cells) to start. If i can keep cost down I may spring for double this.
• Looking for suggestions on BMS (this decision likely driven by the choice of inverter/charger).

The Inverter/charger and remaining components (this is where I need the most help at the moment):

• Victron Dual (one for each leg) Quattro 5kVA (any more affordable options suggested?)
  • Goal here is to be able to supply the coach with similar power that shore or generator can do.
• Lynx "power in", "shunt", and "distributor" (again, suggestions welcome)
• Cerbo GX for connectivity
• Surge protector for shore power (watchdog?)
• Various disconnects and fuses (add more info here later).

The loads (going to begin testing with a Kill-a-watt this weekend):

• 3 x 15k BTU AirConditioning units (1.2-2kw each w/compressor running)
• Microwave/oven combo (unknown at this time)
• Refrigerator (300W)
• Air Fryer (1.7kw) everyday use roughly 20 min/day
• Ice maker (unknown but we may not use this, we're not ice people)
• Stove (dual eye electric) (we'll likely use a propane griddle mostly, have a 45 lb tank on board)
• Water heater (unknown)
• Baseboard heating (don't want to know, haha, use propane heat if possible)
• Lights (working on converting all to LED)

I'll try to add more to this post as I have time.

Thank you all so much in advance for any help. I hope to figure out how to make a pretty schematic of it soon as well.

 

[RCinFLA]

Looks good. I was going to suggest the dual Victron 5 kVA Quattro's.

They will give you separate AC inputs for shore power and generator, and supplement AC input power from batteries when shore power is low.

Only thing is your battery capacity might be a bit light for totally off grid day with air conditioning.

You may need to add MicroAir Easystarts to your air conditioners to reduce their startup surge current when running on inverters alone.

 

[justinm001]

Sounds like a great plan. The quattros will do the ATS for you as you plug the shore and genny into in 1 and 2 then it'll pick which to use. They also handle 100amps each. To cut costs you could go with 5k MP2s which are about a grand less each but no ats.

The lynx power in is pointless. The lynx shunt doesn't have Bluetooth so less features than the smartshunt but uses the network cable instead of the stupid other cable that I had to superglue. Also the lynx shunt looks a lot better and you need it to light up the distribution lights so you can see if they're blown.

Look into if your genset has auto start or how you can add 2 wire autostart. This is great because it'll plug into the cerbo and you can have genset autostart based on battery charge.

BTW I have a very similar system in my 08 Prevost xl2. I think my 12v Quattro just dies so ill likely have the same system as you soon.

 

[justinm001]

One more thing. Keep the starter batteries separate do not use them for anything house related. Have a separate genset battery and for 12v house use a dc to dc charger. You don't want to run out of batteries and can't start the coach or genset. They're your backups.

 

[Rocketman]

A few ideas…

Go with the Smartshunt (and optional battery temp sensor) instead of the Lynx shunt (see reason above and it’s cheaper.

Substitute a Power In for the distributor. You can find on YouTube on how to add fuses to the PowerIn - then the only thing you are missing is the led lights (you probably won’t use those anyway) and save a few bucks.

If your current generator is not 2-wire start - there are modules to make it work (Atkinson).

Plan your solar at this stage - run the wires - that way you know it will be ready.

Solar is more important than the Dc-Dc chargers. Solar works everyday (even if it’s not as much as you would like) Dc-Dc only works when you are driving. If necessary put half the solar in now and finish later.

Get the right tools for the job upfront- crimpers, wire cutters, etc. The right tools make all the difference.

Make a drawing and post it here - with all the details- fuses , wire size, equipment, etc. you will get good suggestions.

Good Luck

 

[justinm001]

A few ideas…

Go with the Smartshunt (and optional battery temp sensor) instead of the Lynx shunt (see reason above and it’s cheaper.

Substitute a Power In for the distributor. You can find on YouTube on how to add fuses to the PowerIn - then the only thing you are missing is the led lights (you probably won’t use those anyway) and save a few bucks.

If your current generator is not 2-wire start - there are modules to make it work (Atkinson).

Plan your solar at this stage - run the wires - that way you know it will be ready.

Solar is more important than the Dc-Dc chargers. Solar works everyday (even if it’s not as much as you would like) Dc-Dc only works when you are driving. If necessary put half the solar in now and finish later.

Get the right tools for the job upfront- crimpers, wire cutters, etc. The right tools make all the difference.

Make a drawing and post it here - with all the details- fuses , wire size, equipment, etc. you will get good suggestions.

Good Luck

He's so right. I just finally got a hydraulic crimper and a small dedicated crimper and they make such a difference.

Temp sensor isn't needed as the Quattro will each come with one plus if he gets a good bms it should report... actually eliminate the need for a shunt, right?

Can't use the lights for distribution unless you have the lynx shunt. I have both shunts and switching from smartshunt to Lynx because it doesn't have Bluetooth I lost the feature for my smartsolar controller to use the smart Bluetooth network and pull voltage at the shunt instead of at the mppt terminals. Even though my lynx shunt is plugged into my solar vecan and all into cerbogx. Idk if those lights do anything other than turn power and the fuse red if blown. I thought they'd tell the cerbo that it's blown but I don't remember seeing it.

The lynx shunt has a spot for anl fuse on red which is nice. Whole thing looks a ton better if you get the distribution. So idk which one to get. I do miss checking via Bluetooth.

BTW Aaron on YouTube walks through his entire setup. His name is camp prevost on YouTube. He did something cool and actually used the powerin as his negative buss bar and put the smartshunt on the red and black terminals. So one side is battery in and other side is outputs. He made some bracket for the smartshunt from copper at the hardware store.

 

[jberger]

I recently purchased a 1989 Bluebird Wanderlodge motorcoach. My family and I will be traveling in it full time over the next year (minimum) and would like the option of living "off the grid" when desired.

I respectfully request your assistance in the design!

My first phase of the build will not include PV panels to cut cost.

Below is my "wish list" which I hope will allow several of you to assist me in building this system (and maybe have fun with the challenge!). Please feel free to correct me on any of the statements I've made or provide better alternatives with your opinion/experience.

General Info:

• The coach has an existing electrical system (that I don't fully understand at this point but working on it).
• 50 amp 240VAC shore power capable (which is split into two 120V/50 amp) for a total of 6kw on each leg.
• 15 and 30 amp 120VAC shore power capable.
• 15kw diesel generator that feeds both legs with 120VAC/50+ amps.
• It has an auto-transfer switch (i think) that switches from generator to shore power.
• Generator has an alternator and 12VDC battery (I'll likely keep this system isolated)
• Main engine (Detroit 8v92 diesel) has an alternator and 12VDC battery system. I'll likely keep this system isolated and continue to run the 12VDC components in the coach off these. May add a 12VDC LifePO4 battery at some point.

Goals:

• Off Grid, use the generator at maximum capable power to charge the 48VDC battery. Hopefully only needing to run the generator a few hours a day.
• On Grid, use available power to charge batteries and supply the coach with power and "boost" capabilities (supplement low shore power with battery).
• Driving, use engine alternator to charge 12VDC and 48VDC batteries. (DC to DC charger here? Orion? suggestions?) (battery to battery charger?)
• PV panels on the roof in the future, but not yet.

The batteries:

• I believe I'd like a 48V system (keep volts high and amps low=better)
• I believe I'll build my own from eve LF280k cells
• I believe a minimum of 14kwh battery (16 cells) to start. If i can keep cost down I may spring for double this.
• Looking for suggestions on BMS (this decision likely driven by the choice of inverter/charger).

The Inverter/charger and remaining components (this is where I need the most help at the moment):

• Victron Dual (one for each leg) Quattro 5kVA (any more affordable options suggested?)
  • Goal here is to be able to supply the coach with similar power that shore or generator can do.
• Lynx "power in", "shunt", and "distributor" (again, suggestions welcome)
• Cerbo GX for connectivity
• Surge protector for shore power (watchdog?)
• Various disconnects and fuses (add more info here later).

The loads (going to begin testing with a Kill-a-watt this weekend):

• 3 x 15k BTU AirConditioning units (1.2-2kw each w/compressor running)
• Microwave/oven combo (unknown at this time)
• Refrigerator (300W)
• Air Fryer (1.7kw) everyday use roughly 20 min/day
• Ice maker (unknown but we may not use this, we're not ice people)
• Stove (dual eye electric) (we'll likely use a propane griddle mostly, have a 45 lb tank on board)
• Water heater (unknown)
• Baseboard heating (don't want to know, haha, use propane heat if possible)
• Lights (working on converting all to LED)

I'll try to add more to this post as I have time.

Thank you all so much in advance for any help. I hope to figure out how to make a pretty schematic of it soon as well.

Come join us at the WOG https://www.wanderlodgeownersgroup.com/
I've got a Wanderlodge LXi, congratulations on your new Bird!

 

[ProfessorPeabody]

Thank you all for the replies so far.

Generator does not have an autostart (that I know of) but does have wiring that I believe could be integrated.


New info:

• The electric range appears to be 220v. I'll need to consider this but believe it's going to be possible due to the dual quattro setup.
• I will create a 12v battery for the 12v components on the coach as recommended and isolate it from the start batteries. Makes good sense to do so. (thanks Justin)
• I will use the Victron Power in rather than the distribution to save some $. (thanks Rocketman)

New Questions:

• Would I be better off getting a basic BMS and use the smartshunt or a BMS that can communicate with Victron? Suggestions?
  • FYI, I like the idea of modular systems. I'd rather have a less expensive/less featured BMS and smartshunt in consideration of component failures. Less features=less to go wrong. Also less expensive to replace dedicated components of a modular system than replacing a feature rich component that has a failed feature that warrants replacement.
• Really looking for suggestions for the two BMS
  
  • 48V
  • 16 cells (3.2V each)
  • 14.3 kwh (280ah @ 48V {51.2V})

I'm currently mapping out the schematic in Canva and will present my drawing for review before the weekend.

 

[justinm001]

As long as the quattros are same model and revision they can be programmed into split phase so you can run 220v without any issues.

Looks like genny needs a controller for auto start so can be added.

 

[RCinFLA]

Most gasoline generators do not have automatic choke control making auto-start problematic.

Diesel generators may have glow plugs that need to be activated before start attempt.

Propane fuel generators are best for auto-starting.

If you do use inverter auto generator start, make sure it gives up after three failed attempts and does not just keep trying to repeat startup attempts continuously until starter battery dies or starter motor fry's.

 

[ProfessorPeabody]

Had a call this morning with Atkinson Electric for an autostart on my diesel generator. Great people and great service. They are looking through the wiring diagram for the Kohler generator on my bus and will suggest the best auto start for my application. I like that their auto starts are dedicated to the function necessary for the application and not a "one size fits all" solution (with dip switches).

RC: I'll have to check on the function of "x qty of failed start attempts". Thank you!

My generator has temperature and oil pressure protection so I won't need that in the auto starter. It also has glow plugs that will be controlled by the auto start's time delays (10 sec preheat before starting). Should be a nice addition to the system. Thanks again Justin for the recommendation!

Come join us at the WOG https://www.wanderlodgeownersgroup.com/
I've got a Wanderlodge LXi, congratulations on your new Bird!

I'm there already for sure, but thanks!

 

[Rocketman]

Here are some things to keep in mind for BMS’s.

Look in the Owners manual for the Multiplus/Quattro you plan on buying. They give a size of battery needed in Amps as well as a suggested size (if I remember correctly).

Your bms needs to provide as many amps as the inverter will need. My guess is a 200a 48v 16s bms will do - but verify it. (Remember you are driving two inverters).

If you cannot find a 200a bms you like, you can get a smaller one and have the bms drive a contactor like a Tyco EV200AAANA (except that one is 12 to 36v - you will need the 48v one).

I used an expensive bms (Batrium) - it a contactor based bms (that’s what I needed for my requirements), I have also used a 12v Overkill bms (nice basic one - but I believe they max out at 100a).

The features I believe are important in bms’s for RV’s.
Bluetooth so you can easily see the bms voltages (and cell voltages).
User setable for voltages.
Low temp cutoff ( last resort - your Victron will do it too).

With putting in a full Victron system, you will need to decide what piece of equipment will control the charging. Your choices are:

1. Each charger uses its own settings to bulk, absorption, and float.
2. Get a bms that can communicate with the Victron Cerbo and the bms controls the charging.

My Batrium bms can do it and at the beginning of my lithium project I was going to set it up that way, but after installing everything I decided to just let each device use it own settings. I just set my charging profile a little bit conservative.

Be sure and turn on DVCC in Victron Cerbo) - it compensate for voltage drop when charging.

When you pick one - ask a question about it here and let those that use it guide you.

Good Luck

 

[justinm001]

@Rocketman I'm just starting to dig into BMS's but if I have a couple 12v EG4 400ah batteries I want to reconfigure to 48v and replace the BMS, then have it work with my SOK and whole Victron system... would I be able to just use a batrium for both rack batteries or should I get a Separate bms for each? Any concern about also having SOK integrate with Victron?

I'm hoping to add 1 or 2 more SOK batteries soon if I have the room so ideally the BMS for these EG4 batteries would just connect to the SOK ones.

Or should I just dump the EG4 and makes more sense to spend the $3500 on SOK ones?

 

[Rocketman]

on the EG4’s As long as you can change the battery cell configuration (changing the buss bars and flipping cells) any 48v 16s bms could be inserted to run the rack mount. just need to solve all the issues.

For Batrium specifically… you would need the Batrium watchmon Core, and then a Cellmate K9 for each 16s battery. You can have many K9’s linked up together. Then all these batteries go to one disconnect (contractor in my case - others use a shunt- trip). The Watchman core watches everything and if something goes “Critical” it activates the disconnect. (You may or may not want their shuntmon).

If connecting the Batrium to the Victron via the CAN-Bus and having the bms control the charging, you would not want other batteries paralleled in. If not having the bms control the charging you could have other batteries Paralleled in - but there are other cheaper BMS’s available than Batrium.

I would contact EG4 and see about getting their 16s bms that fits the case nicely.

Or contact SOK and get 16s bms’s that will communicate with the other SOK’s.

 

[justinm001]

Thanks for the great advice. I'm thinking the SOK compatible bms makes the most sense.

 

[Indy951]

I would consider a Schneider XWPro as an option to the dual Quattro setup.