I did a quick search, but couldn't find anything on this, but will Ford be allowing for dual alternators on the Transit? The reason is that the second alternator could feed a set of house batteries, which would feed a decent inverter. If this is possible, it would be nice for running electrical appliances like a microwave in an upfitted van.
Additional alternator for house batteries?
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Mercedes offers the mounting brackets for a second alternator for the Sprinter as an option, but I think they are the only ones. RAM doesn't offer a second alternator option for the ProMaster either as far as I know.
Having a stand-alone electrical system for the "house" is something I would also pursue if practical. One advantage is that voltage would not be limited to 12 Volts. Of course that too has pros and cons.
Having a stand-alone electrical system for the "house" is something I would also pursue if practical. One advantage is that voltage would not be limited to 12 Volts. Of course that too has pros and cons.
It looks like American Power (americanpowerinc.com) has a 360 ampere secondary alternator with a bracket, just for the Transit. This allows me to keep the chassis electrical system separate from the house electrical system, which is quite important to me, as Chance mentions above.
If this is true, then I can feed a house battery bank from that. Add an Onan generator, a generator controller, and a Magnum Energy hybrid inverter (which makes up for low voltage by supplementing from the batteries), and any electrical item past the inverter will have a clean 120VAC supply, regardless if the power is coming from the engine, the Onan, shore power, or solar.
If this is true, then I can feed a house battery bank from that. Add an Onan generator, a generator controller, and a Magnum Energy hybrid inverter (which makes up for low voltage by supplementing from the batteries), and any electrical item past the inverter will have a clean 120VAC supply, regardless if the power is coming from the engine, the Onan, shore power, or solar.
The Sprinter system is engineered by Mercedes so I'd bet they have taken most things into account. You can see pictures of this option on their web site.
360 Amps at 12 Volts is more power than the 2800 watt Onans typically used with vans. Did you consider eliminating the Onan? Just curious if you considered idling the van versus adding a generator?
You do not need two alternators to run a microwave in a conversion.
Attached is my electrical diagram for the Transit. It is very similar to what I had in the sold 08 Sprinter. The Sprinter house electrical was completely separate from the Sprinter vehicle electrical. The house 12 volt system was not even grounded to the chassis. If I wanted I could have removed the house 12 volt system and without changing any wiring it would have worked in the driveway.
What I did in the Sprinter was not the normal RV setup that used the vehicle 12 volt alternator to charge the house battery. There are numerous things wrong with the "normal" RV setup:
1. You do not charge the house battery with a quality 3 stage (bulk/absorb/float) charger.
2. The alternator charge profile is not matched to your house battery.
3. You are charging two different size batteries at the same time.
4. You may be charging two different types of batteries at the same time (Flooded and AGM).
5. You would be charging two different age batteries.
6. You probably would be charging two different brand batteries with different charging requirements.
7. You could overload the alternator.
The solution that worked well for me was to have two inverters. A "vehicle" inverter that was powered by the Sprinter and a "house" inverter that was powered by the house battery. The vehicle inverter was a 600 watt pure sine inverter to provide 120 volt power while driving. That 120 volt power was "shore" power. I also had a real shore power cord. A 3 position battery selector switch (Blue Sea # 9009) could select the vehicle 120 volt power or real shore power or off. The 120 volt power then went to a Magnum MMS1012 1000 watt inverter/charger/transfer switch. The Magnum has a programmable charger where you tell the charger the battery size and type. It then provides the correct charge profile for that particular battery.
The rest of the electrical system included a 255 amp-hr Lifeline AGM 8D battery, the Magnum RC-50 controller and the Magnum BMK battery monitor. I would set the remote to read SOC (state of charge) to keep me informed about the charge level in the battery. The solar system was additional. Solar panel was a 205 watt panel and the solar controller was a Morningstar Sunsaver 15 amp controller. Solar controller was also a smart charger that has bulk/absorb/float matched to the battery type. I went for a year without using either shore power or "shore" power from the second inverter. I did cheat by turning on the vehicle inverter while driving so that my largest load (4 amp DC refrigerator) ran on 120 volt power instead of the house 12 volt power.
The 1000 watt house inverter would run a cheap ($50) K-Mart 600 watt Proctor-Silex microwave. Microwave is ideal because it has old fashioned mechanical dials without a clock or pushbuttons. When not running it would not use any power. Besides I soon learned not to have the Magnum inverter on unless I needed 120 volt power. It used 7% of my battery capacity just being on overnight without any load. They use a lot of power just being on. The microwave used about 1% ot the battery capacity for every two minutes of use.
Transit system will have a few upgrades. Vehicle inverter size will be increased from 600 watts to 1000 watts. I will use the vehicle inverter while driving to charge the house battery or heat shower water electrically or power a 750 watt electric baseboard heater in rear of van. The larger inverter will allow me to charge at the full 50 amps allowed by Magnum, reduce the 5 gallon water heating time from 45 minutes to 30 minutes and I can add the baseboard heater. The solar panel will go from the 205 watt panel to a 300 watt panel. Same physical size. About $75 more that the going $1/watt cost of solar panels. Should be worth the extra cost on grey days.
This design worked very well for my application. I did buy the HD alternator and the dual AGM batteries in my Transit. I also bought remote start that will allow me to heat up van in morning without getting out of the sleeping bag. I let the van interior get cold at night and I stay warm with a 12 volt heating pad under the zero degree sleeping bag. I also wear a balaclava to keep my head warm. No heater and very little refrigerator run time makes for a quiet nights sleep. Also very stealth.
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From their website Ford Ambulance Transit series 150 250 350 High Output Alternator with Smart Charge it seems that the product that you mention is a heavier duty replacement for the OEM alternator, not a dual alternator system. Or is it another product that you are referring to?
Orton, all design involves compromise, balancing pros and cons. Since your design keeps coming up I'd like more general information on both sides of the issue in order to compare fully. I don't need details at this time.
You've made great points regarding issues that are wrong with the typical RV system used throughout the RV industry. You've also made a case for what's right with your system. But in fairness, we need to also weigh what's right with typical RV electrical system as well as what is not right with yours.
Can you take a minute or two to also enumerate the standard RV Pros as well as the Orton Cons. Basically I'd like to see both Pros and Cons of both systems.
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And to confuse you more... 
Here's another approach to the issue. I'm quite satisfied with how mine is working. We used it on a trip this past weekend and had plenty of power for microwave, computers, charging phones, additional lights, and ...
http://www.fordtransitusaforum.com/camper-vans-conversions/6433-electrical-guts-house-system.html
Here's another approach to the issue. I'm quite satisfied with how mine is working. We used it on a trip this past weekend and had plenty of power for microwave, computers, charging phones, additional lights, and ...
http://www.fordtransitusaforum.com/camper-vans-conversions/6433-electrical-guts-house-system.html
One of the reasons for my post is to do just what you are asking. I am sure there are people smarter than me on the subject. I am not an expert on electrical. I expect we will get some very pointed comments about various methods for charging house batteries. There are pros and cons to every method. The post may bring out issues that I did not consider or did not understand. I do know that the design did work very well in the Sprinter so I will copy it for the Transit. Let others point out what is wrong with the method. There are several negatives:
1. Not efficient to convert 12 volts DC to 120 volts AC and then back to 12 volts DC. You lose about 30% to heat. Not a problem if you seldom use the backup charging method. My primary house battery charging method is the solar panel. Also I doubt that anyone can measure the slight change in mpg. To me the energy is free while driving.
2. The standard RV system is less expensive.
3. The standard RV system can be wired to allow the house battery to start the vehicle.
There is another design that also provides most of the benefits of my design. Have one inverter with a selector switch to select 12 volt power from the house battery or the vehicle 12 volt system. The 120 volt inverter output can power a stand alone charger to charge the house battery. A second selector switch could select either real shore power or power from the inverter.
Lets see what comments we get from others.
Here is another option DC to DC charger
I am considering this as a backup for charging house batteries, primary is solar. looks like it can be switched on by ignition signal, or manual switch if the house battery is low and the solar input is low for some extended period.
I use one of these (different brand) for charging my aircraft battery when plane is parked at night as solar is not an option.
I agree with first two, but not sure why you don't think that just about any 12-Volt house-system battery can't be used as an emergency start for engine, including yours. Couldn't you connect jumper cables from your house battery to start the engine on Sprinter? If so, would it be that different to hard wire with emergency-start switch like most RVs?
With the two inverter system you do not have heavy 12 volt wiring connecting the two batteries. Much smaller wire size from vehicle inverter to house inverter due to 120 volts instead of 12 volts. You could use jumper cables.
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In my rats nest there is a normally open switched and fused line between the house batteries and the vehicle batteries. It's a boat switch I got on Ebay. Obviously, it is normally open. Also, I won't use it as jump battery, just as a dump of electrons: close switch, wait about 10 minutes, open the switch, and use only vehicle batteries for starting. I'd want to disconnect my charging/maintenance circuits before I did a full jump start and use jumper cables.
I did close the jump switch one time (with the van off) and watched the voltages converge. No smoke. That was my test.
But you can add the extra wiring if you wanted, right? No different than RV standard system.
Keep in mind that battery charging current until recently was limited to no more than about 100 Amps, and more recently alternators could do up to 200 Amps if battery bank is large enough. On the other hand starters require a lot more current. That's why cold cranking amps are so high.
You could if you think the expense is worth the rare occasion you might need it (if ever) instead of calling AAA.
I think you may be missing my point. These emergency start circuits require heavy wiring regardless, and basically connect the house battery to auto battery in parallel. Unless I'm missing something, it seems it can be done just as easily with your system as with traditional RV setup. That's why I didn't follow your initial remark about that being a "pro" for RV setup. I don't see it that way because it's essentially the same no matter what kind of system one has, as long as voltage is the same 12 Volts.
Fully agree with your statement. Can be done. But why spend the money if the added wiring is never used? With a normal RV that connects the two batteries together, the wiring is existing so no extra cost. With the two inverter design the heavy gauge wiring does not exist (one of the benefits of the design). It could be added if you believed it is a requirement to be able to start your vehicle with the house battery. I do not see the need for that ability in my conversion.
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