What Size Generator do I need

I know what size generator I need to provide power to run my BH3875 off grid but if all I want is enough to power the lights and keep the residential fridge running while stopped for brief periods or even camping without a/c overnight, how much is too small?? how do you hook up a small generator? if all I really want to do is run off the 12 volt stuff and fridge, don't I just need to keep the batteries up? is there a "charger" on board that does that when I'm hooked to shore power or running off the truck down the highway?

As you can see from these very uninformed questions, I'm a bit confused about the power needs of this unit. Had it about 5 months, 3-4 trips with no need to power anything yet (i.e. overnight in Wal Mart parking lot, etc); but if that's all I wanted to do and NOT use a/c, what size/type of generator do I need and how do you hook it up? I know you can just use step down cord on your 50 amp shore power but don't want to starve the most basic needs??

Nothing I have or can find will tell me these things. If we have something posted, it doesn't come up with my search. You guys have always been the best so I'm coming back to the wizards. help please??

yes, you have a converter that charges the batteries when you are connected to shore power (converts 110V to 12V and charges the batteries). As well the batteries (12V) will be charged from the truck when you are travelling down the road and connected through the 7 pin connector. The 7 pin will charge at a low amperage (about 1-3 amps).

When connected to shore power the amperage drawn by the shore power is dependant on the state of charge of the batteries. At low voltage the batteries will draw about 1000W (you probably have a 80Amp converter).

A 1000W or 2000W generator would be sufficient to charge the batteries for most scenarios. I have had good success with the Honda 2000W - balance between cost, performance, weight. Note: to bring a low charged battery back to 100% takes up to 72 hours; however with the Progressive Dynamics "smart" chargers the battery charge can be brought back to near 80% in a short time. Here is a good chart from Progressive Dynamics. Click for link.

Hope this helps.

Brian

1st question that needs to be answered, your DC system is powered by a CONVERTER/charger which also charges your batteries when on pedestal. Your battery is also charged by your 7 pin while you are driving, however it takes all day driving to charge that battery from 50% to full. The battery is required to operate all your DC system and your electric brakes and your breakaway brake system.

It does not take a large generator to keep the batts charged, perhaps 1500 watts. considering you have a residential refrigerator. Find out how many watts the charger you are using consumes add about 10% and that is the minimum you can use to power that charger.

But let talk about something more practical, you have a nice rig there, and it takes a 5500 ONAN to run everything. The ONAN is very fuel efficient, built in and can be started from the inside, its emission are 50 state approved, and the noise emissions are approved by the national forest service.

Why don't you consider putting the correct generator in your rig so that you can enjoy it, get the most from it and add value to your rig at the same time? If you and your brother in law do the job, you can put it in for about 4k plus or minus.

teasac69 said:

I know what size generator I need to provide power to run my BH3875 off grid but if all I want is enough to power the lights and keep the residential fridge running while stopped for brief periods or even camping without a/c overnight, how much is too small?? how do you hook up a small generator? if all I really want to do is run off the 12 volt stuff and fridge, don't I just need to keep the batteries up? is there a "charger" on board that does that when I'm hooked to shore power or running off the truck down the highway?

As you can see from these very uninformed questions, I'm a bit confused about the power needs of this unit. Had it about 5 months, 3-4 trips with no need to power anything yet (i.e. overnight in Wal Mart parking lot, etc); but if that's all I wanted to do and NOT use a/c, what size/type of generator do I need and how do you hook it up? I know you can just use step down cord on your 50 amp shore power but don't want to starve the most basic needs??

Nothing I have or can find will tell me these things. If we have something posted, it doesn't come up with my search. You guys have always been the best so I'm coming back to the wizards. help please??

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Take a look at the Honda EU 2000, it is exactly what you are looking for. The are lightweight (under 50 pounds), fuel efficient( 1 gallon of gas will last longer than 8 hours), and extremely quiet. The produce the most stable current which allows the most sensitive electronics to be powered by them like computers. They do not have the peaks and valleys in their current like regular generators. These are called inverter generators. Other manufacturers produce similar devices but the honda is the top of the line and pioneered the technology. you can have one running right next to you and carry on a regular conversation unlike the lawn mower sounding generators. The great think about the 2000 series is that if you decide to start boon docking later on, you can buy a second unit and run them together which would be more than enough power to run your entire unit. The MSRP is around $1150 but I have seen them advertised for around $800.00 or so.

Just about any suit-case generator will do what you need. I have used a 1850 watt Coleman generator exactly as you described.

szewczyk_john said:

Take a look at the Honda EU 2000, it is exactly what you are looking for. The are lightweight (under 50 pounds), fuel efficient( 1 gallon of gas will last longer than 8 hours), and extremely quiet. The produce the most stable current which allows the most sensitive electronics to be powered by them like computers. They do not have the peaks and valleys in their current like regular generators. These are called inverter generators. Other manufacturers produce similar devices but the honda is the top of the line and pioneered the technology. you can have one running right next to you and carry on a regular conversation unlike the lawn mower sounding generators. The great think about the 2000 series is that if you decide to start boon docking later on, you can buy a second unit and run them together which would be more than enough power to run your entire unit. The MSRP is around $1150 but I have seen them advertised for around $800.00 or so.

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So can I assume you just plug the Honda in to your regular shore power cord? so no danger in starving out some motor starting, i.e. fan that runs on 120v. I fully realize the need to manage the number of items running when on the light duty generator, just trying to let me turn the truck off and rest a while or visit some museum or site where we are not plugged in.

Jim, thanks for your input on the Onan. I appreciate that is the perfect solution to my question since it does fully power everything. My concern is I don't really want to haul that weight around when I'm not using it. I'm not really an off grid kind of guy and my wife sure isn't but just needing some light duty between longer stops and shore power.

I'm also needing to clarify one thing you guys have answered. I understand the batteries are being charged on shore power, but how is that being done? separate charger or part of the inverter? I've read the diagrams and info in the HUG and just thick headed enough I still don't get where the "CHARGER" for the batteries is located? Off the truck while driving, off the shore power when plugged in but what "device" is actually charging the batteries?

thanks for your patience guys, I know you're probably going, sheeesh, doesn't this guy know anything????

Found a guy in my area with a 1800 Ryobi (2000 starting) suitcase gen for $300, claims new in the box never used?? anybody know these things? Sold by Home Depot, parallel capable, supposed to be very quiet?

you would need an adapter to go from your power cord down to a regular 15 amp plug which would then be plugged into the generator. These are readily available. You can then go about using your unit but you need to remember that you do not have full power. Microwaves, electric side of the hot water heater, AC units, and other heavy usage items should not be run when hooked up as you said in the original post. When you are plugged in you battery is still powering the 12 volt items in the coach like the lights but the battery is receiving a charge at the same time.

I have no experience nor have I ever seen the ryobi unit in use.

FWIW: Here's my opinion and what I did. I had the generator prewiring in my rig and could have gotten the Onan. I chose the Honda 2000 then added a Honda 2000 Companion for a total of 26.6 amps out through a 30 amp socket. Both cost half the Onan and both together weigh much less. I use only one Honda unless I want to use the microwave OR a/c, OR I want to charge my inverter batteries (Magnum 2812 w/ 4 big 6 VDC bats). My house 12VDC comes from two 12V bats on the standard Power Wizzard converter. The gasoline Onan is a fuel hog by comparison, and the propane version that is usually used in these rigs is even more expensive to operate. Since I had the generator prewiring which includes a junction box and auto transfer switch, I connected a 30A cord to the junction box in the generator compartment and hang it over the left front propane tank. This give me two places to plug into 120VAC. This is handy since I like my generators up front and some cgs have power at the front of the site. Hope this helps!

From a fellow VN vet.

2000 Watt Honda or Yamaha generator will work fine for what your looking for. Light weight and don't take up much room. When your running you generator the battery will be charging through your power converter. It will run your lights and refrig. You can run your hot water heater on propane and you could leave you refrig on propane as well while your off the grid but you'll still be using a small amount of current for the fridge controls. We chose the Yamaha and it works fine for us. Weighs about 44 lbs.

teasac69 said:

I'm also needing to clarify one thing you guys have answered. I understand the batteries are being charged on shore power, but how is that being done? separate charger or part of the inverter? I've read the diagrams and info in the HUG and just thick headed enough I still don't get where the "CHARGER" for the batteries is located? Off the truck while driving, off the shore power when plugged in but what "device" is actually charging the batteries?

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The charger/converter is located behind the basement wall it is powered by shore power or any other AC source that you are using. In your case when you connect that Honda as someone described the charger will be operating. You can turn it off by its breaker if you need to.

For your usage, a small generator may not even be necessary, if you do an energy survey, you might be able to dispense with a generator altogether, by increasing the number of batteries you have and installing solar to support you inverter. That is what I do, I only use a generator to run air conditioners, I can run 3 days easily on solar, without recharge, but in normal usage i'm 100% charged by noon each day. I have a home theater, microwave, AC appliances, the only thing you cannot possibly run are the airconditioners and the water heater. Your existing charger and a solar charger work well together, so its just a simple matter of installing panels and a solar charger, you already have the inverter. If that inverter only runs your refrigerator then that can be easily remedied by installing an appropriate inverter and powering breaker box. When installing an inverter in this simplistic way, you will have to manually turn off the appliances that normally run on AC, such as the air conditioners, and water heater.

If you can't run air conditioners what good is a generator? Just go solar it is cheaper and requires NO fuel.

Since you have the residential refrigerator powered by inverter off your batteries, the generator will have a bigger load than if you had a Norcold or Dometic rv frig on gas. The residential frig likely draws around 7-8 amps from the inverter or the generator - thats over half the capacity of a single 2000 watt generator. A single 2000 watt generator may work, but you may decide to add a second 2000. If that should be the case, you can only do it by synchronizing the two generators. I think the Hondas would be easiest because of the Companion version. Keep in mind the current output of whatever generator(s) you get must be greater than the anticipated load. The small generators are quiet except when working hard - then they are annoying. Don't even consider anything that isn't an inverter generator unless you go to an Onan.

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This system can run your rig (except AC and water heater), 24 hours per day indefinitely. It can run your rig for 48 hours without sunshine if you are judicious with power usage. FREE