Gen amps

[goldwing1961]

what size portable generator can run the ac, microwave and tv at same time.

[Bob_C]

How big of an A/C?

[twinboat]

3600 watts is 30 amps so that should do it.

With my 30 amp RV I can run the AC, microwave, fridge and TV.

[aether_one]

Originally Posted by goldwing1961

what size portable generator can run the ac, microwave and tv at same time.

AC = 17 Amps running
MW = 15 Amps running (max, big MW)
32 amps at 120 VAC = 3840 VA
At .8 pf that would be 4800 watts running.
Add some more for starting either appliance and misc loads and you are probably looking at 6 KW.

Best I can do without specifics for your RV.

[Beau388]

Originally Posted by tfryman

AC = 17 Amps running
MW = 15 Amps running (max, big MW)
32 amps at 120 VAC = 3840 VA
At .8 pf that would be 4800 watts running.
Add some more for starting either appliance and misc loads and you are probably looking at 6 KW.

Best I can do without specifics for your RV.

Agree. Starting amperage for an A/C (capacitor start) is 2 to 6 times the running amperage. Stalled rotor amperage draw for a typical A/C compressor is 47 amps. A 13,500 btu A/C will often stall a 3600 watt genset when cycling at 95 degrees and above.

[AnotherMike]

Originally Posted by goldwing1961

what size portable generator can run the ac, microwave and tv at same time.

What size A/C, and does it have the soft-start option (sometimes called the easy start)? That option really lowers the power load during compressor start, and can stretch the life of your compressor motor and generator.

Look at the microwave and TV (and anything else). Find the watts numbers on the label.

Look at the air conditioner and see if it has a watts number on the label, or if not look for amps. If all you have is an amps number then multiply by 120 to get watts. Double the the number for compressor start (5 to 10 seconds). Some big AC units can run six(!) times the running current as a starting surge. I'll use double for this example.

Add up the watts numbers, and add some padding for future growth.

For example, my TV runs about 50 watts. My microwave is 1550 watts.

My air conditioner book gives these numbers:
13,500 Btu
115vac, 60hz, 1ph
12.4 Compressor-rated load amps
2.7 Fan motor-rated load amps
13.7 Heater amps

So, in AC mode you have fan plus compressor=15.1 amps plus starting surge.

In electric heat mode you have fan plus heater=26.1 amps.

Note that electric heat mode is not heat pump mode - in heat pump mode you'd use the AC mode numbers.

So multiplying volts*amps to get watts you have 120*15.1=1812 watts.
If you do not have the soft start option you can figure about double that (3500 watts) for 5 to 10 seconds when the compressor starts.

So my AC alone needs a minimum of 3.5kw for 1 unit or about 5.0kw for 2 units.

Starting with 1812 as the bare minimum from the AC plus 1550 watts from the microwave plus 50 watts from the TV totals about 3500 total watts plus the starting surge from the air conditioner(s).

I'd start with an absolute minimum of 4kw, and a 5kw genny would be better. A 6kw will give you some headroom for growth. My 1985 RV came with a 6.5kw Onan.

Your numbers will probably be different.

And I'd definitely add the soft start kit to your A/C unit(s) just to reduce the starting surge. It's a cheap way to lower your power needs and extend the live of your AC compressor motor and of your generator.

[Bob_C]

Just checked this trailer....with tv and Sat, 2 amps....micro 16 amps, 13,500 A/C with Easy start capistator, 12 amps and that was start up and stayed the same running....readings from digital Progressive EMS readout....

[jcussen]

Originally Posted by AnotherMike

What size A/C, and does it have the soft-start option (sometimes called the easy start)? That option really lowers the power load during compressor start, and can stretch the life of your compressor motor and generator.

Look at the microwave and TV (and anything else). Find the watts numbers on the label.

Look at the air conditioner and see if it has a watts number on the label, or if not look for amps. If all you have is an amps number then multiply by 120 to get watts. Double the the number for compressor start (5 to 10 seconds). Some big AC units can run six(!) times the running current as a starting surge. I'll use double for this example.

Add up the watts numbers, and add some padding for future growth.

For example, my TV runs about 50 watts. My microwave is 1550 watts.

My air conditioner book gives these numbers:
13,500 Btu
115vac, 60hz, 1ph
12.4 Compressor-rated load amps
2.7 Fan motor-rated load amps
13.7 Heater amps

So, in AC mode you have fan plus compressor=15.1 amps plus starting surge.

In electric heat mode you have fan plus heater=26.1 amps.

Note that electric heat mode is not heat pump mode - in heat pump mode you'd use the AC mode numbers.

So multiplying volts*amps to get watts you have 120*15.1=1812 watts.
If you do not have the soft start option you can figure about double that (3500 watts) for 5 to 10 seconds when the compressor starts.

So my AC alone needs a minimum of 3.5kw for 1 unit or about 5.0kw for 2 units.

Starting with 1812 as the bare minimum from the AC plus 1550 watts from the microwave plus 50 watts from the TV totals about 3500 total watts plus the starting surge from the air conditioner(s).

I'd start with an absolute minimum of 4kw, and a 5kw genny would be better. A 6kw will give you some headroom for growth. My 1985 RV came with a 6.5kw Onan.

Your numbers will probably be different.

And I'd definitely add the soft start kit to your A/C unit(s) just to reduce the starting surge. It's a cheap way to lower your power needs and extend the live of your AC compressor motor and of your generator.

In heat mode, your ac draws 26.1 amps? How is that possible on a 20 amp breaker? When heat strips come on, compressor shuts off, so load is blower and heat strip, which keeps it around 15 or 16 amps.

[vsheetz]

Our previous RV was 30a shore cord and 5500w generator. It would run two air conditioners, and shed one air conditioner when the microwave was used.

[twinboat]

Wow, not sure where you guys are coming up with these amp or watt numbers.

My MH, and millions of others, are equipped with Onan 4000 watt generators. They build them at 4000 watts so they can be converted to propane and still produce 3600 watts.

They are used to run a Microwave/convection oven, one Coleman's rooftop air conditioner, a battery converter, a gas/electric fridge and assorted other electric devices.

I've run them my generator in 95 degree heat, used all of the other appliances, and never had the generator overload.

As I mentioned earlier, I have a standard 30 amp ( 3600 watt ) MH.

Suggesting that he will need more then 3600 watts, to do what he proposes seems excessive.

I also wonder why the death if a rooftop AC unit is low volts, but some suggest that a limiting device, like an EZ Start, that ramps up the voltage, to get it running, will prolong the AC units life. You can't have it both ways.

[bigchick]

i'm making an assumption that you have a 30 amp unit as you said 'the a/c' and not the a/c's". a 3600 watt generator will produce 30 amps so basically it will provide the same amount of power as shore power. with this if you can run it on shore power you can run it on the 3600 generator. getting anything larger than 3600 watts for a 30 amp rv is overkill. the 30 amp rv breaker will trip before you can use the excess power.

[AnotherMike]

Originally Posted by AnotherMike

My air conditioner book gives these numbers:
13,500 Btu
115vac, 60hz, 1ph
12.4 Compressor-rated load amps
2.7 Fan motor-rated load amps
13.7 Heater amps

So, in AC mode you have fan plus compressor=15.1 amps plus starting surge.

In electric heat mode you have fan plus heater=26.1 amps.

Originally Posted by jcussen

In heat mode, your ac draws 26.1 amps? How is that possible on a 20 amp breaker? When heat strips come on, compressor shuts off, so load is blower and heat strip, which keeps it around 15 or 16 amps.

Sorry about that, I was in a hurry to finish my reply while I was still on break at work, I added compressor+fan+heater together instead of just fan+heater and didn't catch it before posting... that should have been 16.4 amps...

[aether_one]

Originally Posted by twinboat

Wow, not sure where you guys are coming up with these amp or watt numbers.

My MH, and millions of others, are equipped with Onan 4000 watt generators. They build them at 4000 watts so they can be converted to propane and still produce 3600 watts.

They are used to run a Microwave/convection oven, one Coleman's rooftop air conditioner, a battery converter, a gas/electric fridge and assorted other electric devices.

I've run them my generator in 95 degree heat, used all of the other appliances, and never had the generator overload.

As I mentioned earlier, I have a standard 30 amp ( 3600 watt ) MH.

Suggesting that he will need more then 3600 watts, to do what he proposes seems excessive.

I also wonder why the death if a rooftop AC unit is low volts, but some suggest that a limiting device, like an EZ Start, that ramps up the voltage, to get it running, will prolong the AC units life. You can't have it both ways.

You may have a "standard 30 amp (3600 watt) MH" but the OP did not enlighten us what he had, and hasn't returned to update his question, so we have no idea what size AC or MW he has, so we have to assume worst case conditions.

And an "EZ Start" doesn't ramp up voltage, it adds more capacitance to the starting circuit to make the phase difference between the starting and running windings larger, providing more starting torque at lower current draw.