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Old 01-20-2021, 02:36 PM   #1
Mini-Skoolie
 
Join Date: Aug 2020
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Year: 2006
Engine: Caterpillar C7
Lightbulb Is it possible to conjoin all Power systems (Solar, Shore, Alternator)?

Hello helpful friends,

I know little about electrical wiring and standards, do's and dont's so I'm coming to Skoolienet to see if any electrical wizards can offer advice.

We are about to install our solar system, and shore power hookups, and I wonder if its at all possible to 'mult' these systems together. I would like to be able to run power off the bus's alternator while its running, or off the solar if the bus is parked off grid, or off shore power if parked on grid.

The reason being we have a handicap lift that I'd like to be able to use if plugged into shore power, so I don't have to start and run the bus every time I want to go in or out. Or to run the split mini AC unit off of alternator power if the bus is in motion (because we removed the OEM AC), or run the house lights and radio off the solar; so on and so forth.

Thanks in advance
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Old 01-20-2021, 06:01 PM   #2
Mini-Skoolie
 
Join Date: Nov 2020
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Engine: Cummins 5.9l 24 valve
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the short answer is yes, and then the ever so slightly longer answer is that depending on how automatically you want all that to happen will be directly related to the amount of money you spend on the system and how much studying your willing to do.
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Old 01-20-2021, 06:38 PM   #3
Mini-Skoolie
 
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Quote:
Originally Posted by Samweld View Post
the short answer is yes, and then the ever so slightly longer answer is that depending on how automatically you want all that to happen will be directly related to the amount of money you spend on the system and how much studying your willing to do.
Thanks Samweld, great short answer. I'm willing to study plenty, but ultimately it seems like a job for a trained professional, especially the alternator hookups and switching..? There already is high voltage leads from the house system to the previous AC unit but matching wattage, etc. seems like a pro should handle it. I think fairly automatic switching would be preferred but i get the impression that is pricey? Do you have and resources you would recommend?

Thanks again
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Old 01-20-2021, 07:23 PM   #4
Bus Nut
 
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Really, in every scenario you described you're running equipment, lights and appliances off the batteries. You mentioned running them off the alternator when you're driving, but the alternator's charging the batteries to which your things are connected (through a disconnect or other separation mechanism). And your solar charges your batteries. And your shore power charges your batteries. In the most simple sense, the batteries are the power source and you just switch (manually or automatically, depending upon your budget and skills as Samweld suggested) the charging mode. Does that make sense?
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Old 01-20-2021, 08:44 PM   #5
Mini-Skoolie
 
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Quote:
Originally Posted by rossvtaylor View Post
Really, in every scenario you described you're running equipment, lights and appliances off the batteries. You mentioned running them off the alternator when you're driving, but the alternator's charging the batteries to which your things are connected (through a disconnect or other separation mechanism). And your solar charges your batteries. And your shore power charges your batteries. In the most simple sense, the batteries are the power source and you just switch (manually or automatically, depending upon your budget and skills as Samweld suggested) the charging mode. Does that make sense?
Yes that makes great sense, except that differs from my understanding of ďShore PowerĒ. I was under the impression that shore power bypassed the solar system (excepting a battery charger of some kind) so that when you, say plugged something in to your wall receptacle, were plugging directly into, and drawing from, the shore power, not your battery bank.

Without knowing the specific draw of the wheelchair lift, I would imagine it would destroy my solar battery bank if that kind of draw were to hit it. Right? Or solar batteries with shore power backing it up might be sufficient ? But I guess in your above scenario the wheelchair lift is drawing off the buss batteries, sooo .. yeah I got lots of home work!
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Old 01-20-2021, 08:47 PM   #6
Mini-Skoolie
 
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Current study material on the subject at hand. Any other book or source recommendations would be appreciated
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Old 01-20-2021, 08:53 PM   #7
Bus Nut
 
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Shore power is AC (120 volts, usually) and is used to power appliances in place of the bus battery/inverter setup. Often, shore power (or a generator) is the only way to power some things...like multiple air conditioners. What you described sounded like you were designing a system that would operate completely while driving, and if that's the case then you could design a system where the "shore power" really only charged your batteries. Electrical systems can be as simple or complex as you want. I was looking at your system from the perspective I got from the subject line, so I had a simple "conjoined" system in mind.

In a simple system, especially for boondockers, everything will run off the batteries (either as DC or as AC, through an inverter) and they charge from solar or engine power. In a more complex system, more popular with folks staying at RV parks, you may have a completely separate system which will only run off that shore power or the inverter...in other words, while driving around you'd not be able to run those 4 rooftop air conditioners without running a genny. I've seen systems where some AC receptacles only operate off generator or shore power. I think most skoolie folks lean towards the simple systems, which give them more autonomy.

We have 4 wheelchair lifts and they all operate off 12 or 24 volts DC. The current draw is high, while operating the hydraulic pump, but it's fairly brief. So, yes, they'll run off the batteries.
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Old 01-20-2021, 09:17 PM   #8
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I just saw your follow up post about books. Those are certainly good. The actual code books which apply are expensive and don't teach "how" to do something, they just prescribe the specs and the manner in which things should be done. The NEC book is $120...but at least it's heavy and has lots of pages! The RVIA low voltage wiring book is almost $50 and it's got about 10 pages of specs, not counting the appendix...really, the thing is hugely expensive for about 16 pages of text. So...The 3 applicable standards books are the National Electrical Code, the RVIA Low Voltage manual, and the NFPA RV standards book. I'm happy to look anything up for you, or anyone here.
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Old 01-20-2021, 09:56 PM   #9
Mini-Skoolie
 
Join Date: Nov 2020
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Rated Cap: 78
you can find a lot of good stuff on youtube about the solar power and skoolie power systems. another site for 12v electrical is

www.the12volt.com
this has a lot of automotive stuff.
i will post some helpful video links tomorrow.

things to search for:
solar inverter/ charger hookup
ohms law
wire ampacity
battery isolator

these will get you started, there will be plenty of stuff to watch.
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Old 01-20-2021, 10:47 PM   #10
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
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Year: 2006
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Quote:
Originally Posted by rossvtaylor View Post
Shore power is AC (120 volts, usually) and is used to power appliances in place of the bus battery/inverter setup. Often, shore power (or a generator) is the only way to power some things...like multiple air conditioners. What you described sounded like you were designing a system that would operate completely while driving, and if that's the case then you could design a system where the "shore power" really only charged your batteries. Electrical systems can be as simple or complex as you want. I was looking at your system from the perspective I got from the subject line, so I had a simple "conjoined" system in mind.

In a simple system, especially for boondockers, everything will run off the batteries (either as DC or as AC, through an inverter) and they charge from solar or engine power. In a more complex system, more popular with folks staying at RV parks, you may have a completely separate system which will only run off that shore power or the inverter...in other words, while driving around you'd not be able to run those 4 rooftop air conditioners without running a genny. I've seen systems where some AC receptacles only operate off generator or shore power. I think most skoolie folks lean towards the simple systems, which give them more autonomy.

We have 4 wheelchair lifts and they all operate off 12 or 24 volts DC. The current draw is high, while operating the hydraulic pump, but it's fairly brief. So, yes, they'll run off the batteries.
Great info, thank you! Firstly, I have a feeling that verbiage and nomenclature will get me in a lot of trouble because Iím only using words that make sense to me and help explain what Iím after , Iím not actually [aware Iím] using technical terms. But based on your explanation it looks like Iím after a hybrid of the simple Skoolie off grid system, and the RVer Genny/shore power style.

While I donít have 4 rooftop units, I imagine Iíll have 1 mini split that I would hope to run off the house batteries/alternator while in motion (if possible?). Now that you mention it, thatís how my lift works, it wonít run when the bus is off and I imagine the battery bank wouldnít be able to power even a full up and down cycle on its own. So yes itís the batteries, but backed up by the alternators constant change. But your right in the sense that it works with only 2 basic HD batteries in my house bank. I bought 4 solar deep cycle batteries and a 3k watt solar array.
So it is fairly matched, house system to solar system.
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Old 01-20-2021, 10:48 PM   #11
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
Posts: 31
Year: 2006
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Quote:
Originally Posted by Samweld View Post
you can find a lot of good stuff on youtube about the solar power and skoolie power systems. another site for 12v electrical is

www.the12volt.com
this has a lot of automotive stuff.
i will post some helpful video links tomorrow.

things to search for:
solar inverter/ charger hookup
ohms law
wire ampacity
battery isolator

these will get you started, there will be plenty of stuff to watch.
Awesome, I will check out all of these ideas, thank you!
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Old 01-20-2021, 10:51 PM   #12
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
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Year: 2006
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Quote:
Originally Posted by rossvtaylor View Post
I just saw your follow up post about books. Those are certainly good. The actual code books which apply are expensive and don't teach "how" to do something, they just prescribe the specs and the manner in which things should be done. The NEC book is $120...but at least it's heavy and has lots of pages! The RVIA low voltage wiring book is almost $50 and it's got about 10 pages of specs, not counting the appendix...really, the thing is hugely expensive for about 16 pages of text. So...The 3 applicable standards books are the National Electrical Code, the RVIA Low Voltage manual, and the NFPA RV standards book. I'm happy to look anything up for you, or anyone here.
Yeah I prolly donít want the code books, more the how toís. I think I will tackle a bit of this myself and bring on a pro electrician to help me finalize, connect and test everything. I will definitely ask you more specific questions as I stumble across hurdles.
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Old 01-20-2021, 11:07 PM   #13
Bus Nut
 
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A question for you, FAEW...if I may call you FAEW... , when you say the lift won't run without the engine running, does that mean that nothing happens at all? No click, no slow pump running, nada? If that's the case, then there may be a solenoid or contactor that's preventing it from operating without the engine running. Or, does it try to run...but it's slow/boggy? If so, then there may be bad connections...they corrode over time. Or they just need more battery oomph (to break out the technical terms) which might be resolved with the house battery bank, being closer to the lift.

I've designed and installed remote village electrification systems and I tend to approach our bus and ambulance (sort of expedition vehicle) systems in the same way. I like to design the electrical system so that shore power isn't required and isn't even a consideration, except for the installation of a battery charger to use when there happens to be power available...or when at home. So, I design the system to power the loads from the batteries. This means compromises...so no electric hot tub, no 4-A/C rooftop setup, etc. But you can certainly run an efficient mini-split A/C unit, you can run tools, you can weld, you can run an electric chainsaw (I've put outside receptacles for just this purpose), you can use an induction cooktop or microwave, and most importantly...you can make coffee. So, my tendency is to design around solar or engine charging and consider a generator or shore power to be "emergency" backups.

Important Note: Related to coffee! I've not found any of the Nespresso machines which will run off a modified sine wave inverter...they require pure sine wave power to even "boot up" and that alone is reason to spring for the extra cost of a pure sine wave inverter. Coffee!!!!
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Old 01-20-2021, 11:33 PM   #14
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I will add my two cents:
I had a second alternator added to my Crown, mounted next to the original one. The second alternator will supply power to a 12 VDC bus whenever the engine is running. The 1 Kw of solar on the roof will also supply power (through a charge controller) to the same 12 VDC bus during daylight hours. Both sources placing potential (and current flow through the 12 VDC bus) will operate the inverter and charge the house batteries. Any 120 VAC circuits will get power from inverter(s) under daylight and or engine running conditions. For backup power when the engine is not running and its dark, I have the option of running the 6.5 KW generator, which will charge the house batteries through an RV battery charging system, and run all 120 VAC circuits (no inverter(s) used with generator). Outside (shore) power provides power the same as the generator to all 120 VAC circuits and charge the house batteries. You will notice that all the above statements referencing circuits used in the RV rely on the batteries used to start the bus engine to not used to run RV things (like refrigerators) you will probably find out the hard way with dead batteries after running the fridge all day and night. Running with a second alternator prevents frying the bus alternator. I found out the hard way on my vintage fire truck, when the batteries got rather low, and once started up the battery charging current fried the alternator. I could not go to the parts store and get another, but had to go to an industrial auto electric shop, and I recall the bill was about $250.
All that said, I will have the ability to cross connect the two electrical systems for emergency reasons. This may sound complicated but it isn't. Changing from shore to generator is as simple as switching two mechanically ganged circuit breakers. Switching to inverter power from shore/generator power is as simple as switching another pair of mechanically ganged circuit breakers and pressing the on switch for the inverter.
This will be safe to operate. For me, my bus is a vehicle that I can travel long distance in and stay in while I do it. It is important that what changes I make keep the vehicle reliable, and make it a comfortable place to stay in. Sorry for the long winded posting but I hope this helps.
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Old 01-21-2021, 01:32 PM   #15
Mini-Skoolie
 
Join Date: Nov 2020
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Engine: Cummins 5.9l 24 valve
Rated Cap: 78
i watched some of the videos from garret towne of AM solar on you tube he has some on system sizing and various equipment. he is of course biased toward the stuff he's selling but im sure the concepts can be applied to other brands.
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Old 01-21-2021, 01:37 PM   #16
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
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Year: 2006
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Quote:
Originally Posted by rossvtaylor View Post
A question for you, FAEW...if I may call you FAEW... , when you say the lift won't run without the engine running, does that mean that nothing happens at all? No click, no slow pump running, nada? If that's the case, then there may be a solenoid or contactor that's preventing it from operating without the engine running. Or, does it try to run...but it's slow/boggy? If so, then there may be bad connections...they corrode over time. Or they just need more battery oomph (to break out the technical terms) which might be resolved with the house battery bank, being closer to the lift.
You can call me that or Ryan. It does nothing, like its deactivated completely when the bus is off. Which i may need to change of i want to enact my plan (insert evil laughter)

Quote:
Originally Posted by rossvtaylor View Post
I like to design the electrical system so that shore power isn't required and isn't even a consideration, except for the installation of a battery charger to use when there happens to be power available...or when at home. So, I design the system to power the loads from the batteries. This means compromises...so no electric hot tub, no 4-A/C rooftop setup, etc. But you can certainly run an efficient mini-split A/C unit, you can run tools, you can weld, you can run an electric chainsaw (I've put outside receptacles for just this purpose), you can use an induction cooktop or microwave, and most importantly...you can make coffee. So, my tendency is to design around solar or engine charging and consider a generator or shore power to be "emergency" backups.
Yes this is essentially what I want as well, excepting that I will be traveling the PNW & Canada and may need to be plugged into shore power more than I'd like. Crazy to know that i could run power tools and even a welder!? I wont have a genny off the hop, but may add one

Quote:
Originally Posted by rossvtaylor View Post
Important Note: Related to coffee! I've not found any of the Nespresso machines which will run off a modified sine wave inverter...they require pure sine wave power to even "boot up" and that alone is reason to spring for the extra cost of a pure sine wave inverter. Coffee!!!!
Great to know! These type things are life critical and would otherwise never be known if my question went unasked. Much appreciated!
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Old 01-21-2021, 01:43 PM   #17
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
Posts: 31
Year: 2006
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Quote:
Originally Posted by flattracker View Post
I will add my two cents:
I had a second alternator added to my Crown, mounted next to the original one. The second alternator will supply power to a 12 VDC bus whenever the engine is running. The 1 Kw of solar on the roof will also supply power (through a charge controller) to the same 12 VDC bus during daylight hours. Both sources placing potential (and current flow through the 12 VDC bus) will operate the inverter and charge the house batteries. Any 120 VAC circuits will get power from inverter(s) under daylight and or engine running conditions. For backup power when the engine is not running and its dark, I have the option of running the 6.5 KW generator, which will charge the house batteries through an RV battery charging system, and run all 120 VAC circuits (no inverter(s) used with generator). Outside (shore) power provides power the same as the generator to all 120 VAC circuits and charge the house batteries. You will notice that all the above statements referencing circuits used in the RV rely on the batteries used to start the bus engine to not used to run RV things (like refrigerators) you will probably find out the hard way with dead batteries after running the fridge all day and night. Running with a second alternator prevents frying the bus alternator. I found out the hard way on my vintage fire truck, when the batteries got rather low, and once started up the battery charging current fried the alternator. I could not go to the parts store and get another, but had to go to an industrial auto electric shop, and I recall the bill was about $250.
All that said, I will have the ability to cross connect the two electrical systems for emergency reasons. This may sound complicated but it isn't. Changing from shore to generator is as simple as switching two mechanically ganged circuit breakers. Switching to inverter power from shore/generator power is as simple as switching another pair of mechanically ganged circuit breakers and pressing the on switch for the inverter.
This will be safe to operate. For me, my bus is a vehicle that I can travel long distance in and stay in while I do it. It is important that what changes I make keep the vehicle reliable, and make it a comfortable place to stay in. Sorry for the long winded posting but I hope this helps.
Wow ok this is great to know. Still digesting this a bit but it seems very relevant to me. I may circle back and ask questions as i understand you and my needs as time goes on. Thank you
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Old 01-21-2021, 01:45 PM   #18
Mini-Skoolie
 
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Quote:
Originally Posted by Samweld View Post
i watched some of the videos from garret towne of AM solar on you tube he has some on system sizing and various equipment. he is of course biased toward the stuff he's selling but im sure the concepts can be applied to other brands.
Great resource. I already have purchased a Renogy System, but the content is still good!
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Old 01-27-2021, 08:40 PM   #19
Mini-Skoolie
 
Join Date: Apr 2019
Posts: 21
Lift power

I have a mini bus with a handicap lift. It runs without the engine running but as someone else said, the pump draws quite a bit. I don't mind one up/down cycle but loading up at an auction I probably cycled it about 10 times with some pretty heavy stuff and the bus just barely started. Lesson learned. The bottom line is that the lift can be run from a single battery.
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Old 02-01-2021, 11:00 AM   #20
Mini-Skoolie
 
Join Date: Aug 2020
Location: Nevada City, CA
Posts: 31
Year: 2006
Engine: Caterpillar C7
Quote:
Originally Posted by nords View Post
I have a mini bus with a handicap lift. It runs without the engine running but as someone else said, the pump draws quite a bit. I don't mind one up/down cycle but loading up at an auction I probably cycled it about 10 times with some pretty heavy stuff and the bus just barely started. Lesson learned. The bottom line is that the lift can be run from a single battery.
Wow gtk. Do you know the make/model of your lift? My house system is 2 standard off the shelf heavy duty pickup truck batteries. Did you have to do what was previously mentioned in this thread, remove a solenoid that, stock, prevented the lift from opening?
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