Generators- how much is enough/too little

[deemac52]

I have a Foerst River Cedar Creek 29RE. It has 50a shore power requirement and I understand that I could limp along on 30a. It has 2 a/c units, residential fridge, faux fireplace that heats and 2 tv's, etc. Virtually every lite is LED & wife odds found of her appliances. Obviously conventional generators (isn't designation 'inverter' redundant?) don't produce 50a. What I don't really understand are how much starting vs running amps I need to cover. Where can I read a primer on all of this stuff? My dealer, while nice people, may have a vested interest in what they advise. Thanks

[rampowerwago]

You need to consider the power you will use rather amperage. Power is equal to volts x amps. Expressed in math form:

P=IE, or power is equal to amps (I) X volts (E)

Lets assume that we have a 50A circuit at 120 volts...

With our equation we would see 50A x 120V = 6000 watts

From this you can add up the load of power in watts of each load and determine how much capacty you need in watts for a generator. A 6000 watt generator should carry enough load to support 50 amps of load.

To muddy the water somewhat, your 50A service is really 2, 50 watt legs which gives you a total 100 amps or 12000 watts of capacity.

But in real life, even running all 3 generators, fridge, TV, etc, I can't imagine the steady state load exceeding 8,000 watts or so. The most load I'ver ever seen on mine was 65-70 amps incoming, or around 8000 watts. Most of the time it is much less.

And for what it's worth, a generator makes electricity (either AC or DC), an inverter uses DC power from the battery to make AC.

[twinboat]

Originally Posted by rampowerwago

And for what it's worth, a generator makes electricity (either AC or DC), an inverter uses DC power from the battery to make AC.

This is how a Inverter Generator works.

The technology generally outputs AC current like most conventional generators, but the current is then converted to DC voltage, and then “inverted” back to clean AC voltage, thus how it gets its name. The advantage to this inversion, is that it maintains a constant flow of current to your appliance.

[Sweetbriar]

A 5000 or 6000 watt generator will pretty much get to where you want to be with little worries about what you can and can't run at the same time. Personally I go with a 3600 watts (30 amp). Generators start getting heavy, bulky and expensive as the power capabilities go up. A little power conservation goes a long way.

And as rampowerwago posted check the watts (power) of the appliances you want to operate to determine how to size the generator. Heating, cooling and the microwave are high demand items. TV's and such are minor. The fridge is a low power appliance but will have a start surge that can push into 20 amp range for a second or so. Same for an A/C compressor but the generator should be able to make past those instances unless they both cycle on at the same time which would be very rare.

I can run everything, except both A/C's and the electric side of the water heater, at the same time with a 3600 watt generator. Got a strange coach in the driveway. 50 amp service with a 30 amp generator.

[bddadles]

Welcome. First you mentioned limping along on 30 Amp. Your coach will work just fine on 30 you just have to be aware that you are not going to run everything at 50 will. For example when I have to run on 30 amp I turn off 1 AC right away. You will learn. But the question was generators.
How are you going to use the rig? Boon docking, Parks etc. Do you want a built in or a portable? I personally carry a Honda 2000. I know it will not run my heat pumps so you have to plan. I could get 2 Hondas and link them or just buy a 3000.
Lots of things to consider. If I wanted to run an AC I would personally go with 2 Honda 2000 and link them (or an equivalent) just because of the weight to move it around.

[Hit_the_Rhod]

Originally Posted by bddadles

Welcome. First you mentioned limping along on 30 Amp. Your coach will work just fine on 30 you just have to be aware that you are not going to run everything at 50 will. For example when I have to run on 30 amp I turn off 1 AC right away. You will learn. But the question was generators.
How are you going to use the rig? Boon docking, Parks etc. Do you want a built in or a portable? I personally carry a Honda 2000. I know it will not run my heat pumps so you have to plan. I could get 2 Hondas and link them or just buy a 3000.
Lots of things to consider. If I wanted to run an AC I would personally go with 2 Honda 2000 and link them (or an equivalent) just because of the weight to move it around.

If you go the 2 Honda route (which we did when we had a travel trailer), there is a member (not me) selling two honda gens with the parallel cable for $1,000 in the classifieds at the top of your screen. Personally, I would probably purchase a Harbor Freight Predator Inverter 3500 for $730.00. They are starting to give the other generator manufacturers a run for their money, and I've always been a Honda fan!

[nothermark]

Originally Posted by twinboat

This is how a Inverter Generator works.

The technology generally outputs AC current like most conventional generators, but the current is then converted to DC voltage, and then “inverted” back to clean AC voltage, thus how it gets its name. The advantage to this inversion, is that it maintains a constant flow of current to your appliance.

The major reason for using an inverter with a generator is to maintain frequency stability while allowing the generator to slow down during periods of low load. It adds significant cost so the economy of the idea in regard to fuel savings can get interesting.

FWIW the inverter will not maintain an more constant power than the generator can put out plus a very short charge time in the bulk storage capacitor feeding the inverter. Much more a sales issue than a technical one.

[Finance]

Just some general examples; a 2800 generator is common in truck campers or small RV's, that's good for one a/c OR the microwave.

4kW is typical in smaller C or A... good for A/C AND micro. 5.5 kw found in larger gas MH will run two A/C plus micro.

Diesel MH usually start at 6kW and go up from there.

A popular combo (and one I have used) is two 2kW inverter gens in parallel for 4kW. Light weight and flexible. There's a lot of choices out there, good luck sorting through them all!

[mmartin]

Originally Posted by Hit_the_Rhod

If you go the 2 Honda route (which we did when we had a travel trailer), there is a member (not me) selling two honda gens with the parallel cable for $1,000 in the classifieds at the top of your screen. Personally, I would probably purchase a Harbor Freight Predator Inverter 3500 for $730.00. They are starting to give the other generator manufacturers a run for their money, and I've always been a Honda fan!

If you like noise and don't like your neighbors, then get the Harbor Freight generator.

[Mr_D]

Originally Posted by deemac52

I have a Foerst River Cedar Creek 29RE. It has 50a shore power requirement and I understand that I could limp along on 30a. It has 2 a/c units, residential fridge, faux fireplace that heats and 2 tv's, etc. Virtually every lite is LED & wife odds found of her appliances. Obviously conventional generators (isn't designation 'inverter' redundant?) don't produce 50a. What I don't really understand are how much starting vs running amps I need to cover. Where can I read a primer on all of this stuff? My dealer, while nice people, may have a vested interest in what they advise. Thanks

Actually some generators do produce 50 amps and 240 volts. That's what my MH has, Onan QD 12,500. It's not very portable though at about 800 lbs.

[Yosemite77]

Trailer Life Magazine has an article in the current issue (March 2018) on choosing and maintaining portable generators. It includes a chart where you can compare starting and rated watts, dB rating, weight, fuel tank size and run time. The other thing which you may want to consider is parts availability. I’ve read where that can be a problem with the Predator generators.

[08Carriage]

I have a 4000 watt Champion generator that I have used couple times but it's noisy I looked at putting in a large 5500 watt onan but cost was at least $6000 installed I just bought 2 Champion inverter electric start, dual fuel 3400 watts and will be linking them weight is 80 lbs each so I can put them any where I want cost $2244.00 the link has a 50A plug see how it goes most 15,000 BTU AC's use 3000 watts

[twinboat]

Originally Posted by 08Carriage

I

most 15,000 BTU AC's use 3000 watts

3000 watts at 120 volts is 25 amps.

I'm pretty sure that all 15000 BTU, RV ACs use 20 amp breakers.

[Sweetbriar]

Originally Posted by 08Carriage

,,, most 15,000 BTU AC's use 3000 watts

That would be one very inefficient A/C. The run of the mill Coleman Mach 15 demands 1560 or so watts. A bit higher if your at the bottom of Death Valley on a sunny July or August afternoon.