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Old 08-10-2020, 09:41 PM   #1
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Batteries with Generator, Alternator, and Shore Power?

I am in the research phase of planning a bus conversion and I have (possibly hairbrained) idea. I'd like to see how feasible it is.

I'd like to run primarily off of batteries. In an ideal world they would be charged via 3 routes: 1) Shore Power; staring the trip charged (or top up if there is shore power where we stay) 2) Via Alternator when the bus is running; and 3) Via generator when the bus is stationary and the batteries drop too low (ideally automatically transferred).

Has anyone accomplished something similar or know of a device that operates as such?
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Old 08-10-2020, 10:43 PM   #2
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They are hubrid cars and electric cars. A Chevy Volt for example.
It has big electric motors and big battery pack to go 40 miles on the battery before the engine has to kick in to power the car. It doesn't charge the battery to power the car, it drives the car directly from the engine. A Prius does both at the same time, actually all three at the same time, drive car, charge battery, power drive motor.

To step this up to a bus-sized vehicle, everything would need to be bus-sized.
They have electric buses. Generally very short term power, they come back to station to recharge often.

BTW, I have built two electric cars and rebuilt many prius, I have three of them right now.
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Old 08-11-2020, 05:57 AM   #3
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I assume you mean the house batteries? Or are you suggesting as Benimble has said hybrid propulsion?


If you do an on board generator, and have shore power you would normally have a "switch" that allows only one source of power, and there are automatic or manual transfer switches available. Either way an on board battery charger would be what you want. These are hard wired in , instead of the cheapy automotive ones.
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Old 08-11-2020, 01:12 PM   #4
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What you describe is bog standard, every system designed for mostly off-grid living must include those elements.

Plus as much solar as you can fit, to reduce genset runtime.

There is no one gadget though, you should start with the battery bank, sized for your energy budget, consumption in Ah per day.
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Old 08-11-2020, 01:24 PM   #5
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It is only hairbrained for propulsion power. ;)
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Old 08-11-2020, 01:28 PM   #6
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I'm also going to assume you're talking about powering household items off a battery bank, and not a hybrid vehicle propulsion system.

Your idea isn't hairbrained at all. Many people here have done this. The difference is a lot of them have solar as well. You didn't list if you are or aren't going to have solar power charging the batteries.

How I would do it, is to use an inverter-charger from aims power, like this one HERE Choose the correct aims inverter charger for your electrical needs and battery bank voltage.

You'll then have a shore power plug and generator wires hooked to an automatic transfer switch. You would then have the output of the transfer switch feeding into the AC input on the inverter charger.

Most of the aims inverter chargers have a low battery auto start generator function that you would wire to your generator, and it will automatically start your generator when the battery state of charge is low. Thereby charging the batteries and taking over the 120VAC loads.

To get it to charge from running your bus engine, you'll need a DC-DC charger that will bump up the 12vdc on the bus to your house battery bank voltage. Have it hooked to a heavy duty continuous relay that's switched on while the engine is running, that way the charger only operates while the bus is running. You'll have to make sure your alternator is large enough to supply the power, but you wouldn't be the only one doing something like this.
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Old 08-12-2020, 07:06 AM   #7
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First of all thanks all for the quick replies.

Let me knock a couple of the question/confusion out first.

My question is limited to house power, not propulsion. Given an unlimited budget, an unlimited amount of time, and no competing interest/commitments/responsibilities a hybrid or electric bus would be lovely to build. But none of those are true. Some of our potential uses rule out all-electric, especially if DC fast charging is off the table.

Second, I do not plan to install solar ... at least at the start. As we envision the use of the bus we do not see the cost and complexity of solar to be worthwhile. In designing the system, I would not mind including the ability to plug solar into the system later (should we decide to spend more time in the bus for longer period in one place).

I have no doubt that I can design and build a system that eventually meets my wants, but was hoping that there might be a single device on the charging side that could take 1-2 vDC inputs (for alternator and possible future solar) and 1 vAC input generator (could easily be switched upstream b/t generator and shore power) which could automatically call an electric start generator when the batteries become low.

Booyah45828, thank you for the detailed post. It is very close to what I was roughly thinking of if there were no RV specific device that can handle multiple inputs of different types. Only it's more thought out than my rough idea and having product recommendations puts me further down the road in design.
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Old 08-12-2020, 07:47 AM   #8
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That settles it then. There's multiple reasons people use solar, and reasons why some avoid it. I simply don't use enough power to require a battery bank If you're traveling more then you are stationary, charging it off the alternator would provide that power.

If solar is your plan, it's better to include it in the original design, but it's not impossible to add it on later. I'm not really sure how a solar charge controller would integrate with the aims inverter charger. I would think I'd only want one device managing my batteries.

You also don't necessarily need an automatic transfer switch. All you'd have to do is have an outlet on your generator, and then leave your inverter charger plugged in to the generator. Then, whenever you'd have access to shore power, unplug it from the generator and into the pedestal.

What it sounds like you're looking for is a dc-dc charger, ac-dc charger, and a dc-ac inverter. I don't know of any all in one boxes that are like that. I'm sure if one was an electrical engineer and was familiar with the components, you could build such a thing.

But if it was me, I'd use an dc-ac inverter charger, and then forget the dc-dc charger. I feel that I just don't drive my bus far enough to get anything worthwhile out of a dc-dc charger. So it would be added cost, complexity and one more unit to fail.
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Old 08-12-2020, 10:43 AM   #9
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We built our bus in a similar fashion. We do not "live" in it and I only plan to have two leisure batteries and not a huge bank.

We just would run the house lights, and some 12v things here and there. Basically not much more than a small camper does.

so with this in mind it is exactly what I did.

I bought a junk pop up camper and among the things I liberated was the AC/DC inverter converter.

I installed it in the bus. sold the junk camper for what I paid.

and then I put in a shore power plug, got it from amazon

So when I am plugged into shore I charge my batteries, and the converter provides up to 20 amps of 12volt DC power to my bus... more than enough for me.

It also houses the breakers for my AC system... 2 fifteen amp, and one 20 amp for the rooftop AC. Originally the plan was if needed to just plug in the Honda 2000 genny and to the shore plug if I needed to charge (but it can't run the rooftop) and I was good.

But then I got lucky on FB marketplace and scored an RV genny cheap.
SO
I am currently adding an Onan 4k petrol genny I scored for $100
I still carry the Honda 2k in the "garage" in the stern of the bus as we use it on the sailboat we tow.



and I also have this spare 1k inverter now going in as well



so the plan will be.

1. shore power
2. Genny
3. 1000w Inverter (runs the mini fridge while we are driving) I may wire the 1000 watt inverter into a THREE WAY transfer switch and I could juice the whole bus. But I don't really boondock a lot. the 1k inverter is a bit much for just a mini fridge but I had it leftover from selling our larger sailboat.

but its all going to depend upon what you want, and the amp draws etc of said devices
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Old 08-12-2020, 10:52 AM   #10
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You are after something like this

they sell them on amazon.. Mine is buried in the galley or i would take a pic of it..

I grabbed this shot off amazon. You feed it shore power and it provides your charging, your entire 12dc system you run to this (it has fused circuits)
and this particular one is 55 amps of AC service (no breakers included so you build your own standard home depot stuff panel, and feed it from this)

30 amps though is what I have, and is enough

but this is the "all in one box"

later you can add solar... as for the AC inputs (genny or shore, just a transfer switch.. also amazon)



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Old 08-12-2020, 06:19 PM   #11
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If shorepower + generator inputs are something you desire, the Samlex Evo and Victron Quattro are both top tier products that have dual AC inputs with built in transfer switch. Additionally the Victron has power assist (meaning if your generator can't supply enough power the Victron will supplement it with power from the batteries), not sure if the Samlex can do this. The Samlex does have a Solar input (you still need a solar charge controller) but it allows coordination between charge sources.



As for a single device that does ALL the things you mentioned I'm not sure it exists (and I'm also not sure there are advantages to an all-in-one beyond less purchasing decisions, and wiring complexity).


There are however single devices that accomplish 4 of 5 functions (DC-AC inverter, AC-DC charger, AC-AC passthrough, Solar Charger, but NOT Alternator Charger). Growatt and MPP are two brands to look into. Victron Easysolar is a top tier option, but not available in the US yet.
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Old 08-15-2020, 05:20 PM   #12
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I hope they start selling Victron Easysolar in the US. Looks like a great product.
You may want to consider a power factor corrected Charger if you plan on running a generator
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Old 08-15-2020, 05:25 PM   #13
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Multiple charging sources

Easy

1. Get an inverter/charger this will charge the batteries when on shore power.

2. Get a battery to battery charger. This will charge the house battery while driving.

3. Plug the generator into the shore power when you need it.

All switch overs are automatic. If you add solar. Itíll work automatically as well.
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Old 08-15-2020, 06:07 PM   #14
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Every inverter/charger Iíve seen is PFC but not all stand alone chargers are PFC. Important if you want to reduce generator run time.
We are ordering a MPP Solar Inverter Charger to test out. They have a built in charger and charge controller. Anyone have experience with them?
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Old 08-15-2020, 07:56 PM   #15
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Quote:
Originally Posted by john61ct View Post
What you describe is bog standard, every system designed for mostly off-grid living must include those elements.

Plus as much solar as you can fit, to reduce genset runtime.

There is no one gadget though, you should start with the battery bank, sized for your energy budget, consumption in Ah per day.
Big enough roof and ypu can fit enough solar to eliminate the need for a generator, shore power or even alternator. Our alternator failed last July. We use the primary bank with a separate solar controleer to charge our 8 battery rig system( also used as backup house batteries durring low sun weeks). We get all of our piwer from the sun and still havent fixed the alternator. We havent driven more than 120 miles after dark yet but so far no problemo.
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Old 08-15-2020, 08:02 PM   #16
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It depends!

Even 3000W solar is not enough for some

between high consumer loads

and weather / shading conditions


OTOH some make do fine solar-only with just 300W
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Old 08-15-2020, 10:37 PM   #17
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My electrical system is basically like what you describe I think...

First off I have 6 6volt batteries in series/parallel to make 1 big 12 volt battery.

I have the shore power and generator wired through a 50 amp automatic transfer switch. So both will go through my charger to recharge the batteries. “Go Power” is the brand of transfer switch. And I have a 3000 watt inverter “Go Power” also, to run my residential fridge and other stuff.

What I did this summer that’s unconventional is I got rid of my bus batteries and I run/charge the bus through the house batteries - the 6 6volt battery bank. The Alternator provides plenty of power to charge up the batteries. I use the generator if we haven’t moved in 2 days. The only thing I might describe as a problem so far is when I start the bus it drops the voltage momentarily that sometimes the inverter cuts power for a moment and I have to reset the microwave clock.
All I did was take the battery cables off the bus batteries and put them on the house batteries.
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Old 08-15-2020, 11:09 PM   #18
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Quote:
Originally Posted by Doktari View Post
Every inverter/charger I’ve seen is PFC but not all stand alone chargers are PFC. Important if you want to reduce generator run time.
We are ordering a MPP Solar Inverter Charger to test out. They have a built in charger and charge controller. Anyone have experience with them?
I've never heard of a Solar INVERTER Charger. most MPPT Solar Charge controllers are designed to work from a solar panel to a battery bank with as much efficiency as possible regardless of the Solar panel Voltages... These work fine in parallel with an Inverter Charger (I have the AIM 3000 Watt Inverter / Charger and two MPPT Charge Controllers AND the Sterling Battery to Battery Charger.

Oh, and the Inverter/charger will start a generator automatically when the batteries get too low. But if you do this, you'll need to add an automatic transfer switch to be "safe"..
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Old 08-16-2020, 01:31 AM   #19
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After reading through this thread, I thought that our implementation might be of interest.

First, the background. Our bus came stock with a 160A alternator. We wanted to run a roof-top air conditioner while driving to help take the edge off of the heat. Adding a 120A (12 DC equivalent) load (the air conditioner) would fry the stock alternator quickly as well as drain the chassis battery bank.

We decided to add a set of house batteries, along with a second alternator. This second alternator is rated at 350A and has the capability to power the air conditioner. The two alternators combined can power the air conditioner at idle.

On the house side, a GoPower inverter powers the AC (120V) for the bus, to include the air conditioner as well as charge the house battery bank while on shore (or generator) power. It also is connected to shore power input (full 50A) and a generator input (still have not connected a generator) through a transfer switch, then an electrical management systeeem (EMS) to check that there is good power before going into the inverter.

When the engine is running, the house battery bank is charged by the second alternator and the chassis battery bank is charged by the stock alternator. We also installed a battery isolation switch batween the battery banks so either both banks could operate as one bank.


Here is the system block diagram:
20200429_162507 AC-DC Electrical Diagram.jpg

Here is the installed system:
20190130_134619 Electrical Distribution.jpg
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Old 08-16-2020, 01:49 AM   #20
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If my alternator dies on me Iíll get a higher amp alt so I can run my air conditioner off it too. Unfortunately Iíve been unable to find a way to install a second alternator on my ISC engine - no brackets available for it.
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