We have been looking at used Class A coaches and it got me thinking (very rare for me) about generator capacity and/or capability.Many of the coaches have a 5000 watt generator and some have 5500 up to 7500. It only makes sense that the larger ones have more capacity but my question runs to actual manufacturer or industry specs. Will the smaller (5K or less) units run the coach appliances well enough or were there a lot of them put out with under capacity gennies? I know this depends upon what the coach has, appliance-wise, but, in general, were most coaches made with enough gen capacity or are there a lot out there with under-powered gens?I have been asking a lot of questions and will probably have many more but it looks like we are going to be seriously looking at used (older) coaches as the year unfolds.Thanks gang.

Class A is a broad term in that it covers from short gassers to really big diesel pushers. Many small gasser A’s only have a 4K watt gen, mine included, but it also only has 30 amp service when plugged in. Whether plugged in or on genny I can’t run everything at the same time. Some A’s have a power management system that will overcome this issue by automatically shutting down certain items when power is needed elsewhere. Years ago I had a Airstream motorhome that had 30 amp service, but a 7500 watt gen. I could run more on the gen than I could while plugged in. As an example on shore power I could run either the front or rear AC, but while on the gen I could run both and more.

There seems to 3 different choices, for 3 different reasons, in deciding what generator got built in. 1) the smaller or entry level units got the venerable but pretty utilitarian 4k unit. 2) the next step up in units, either in quality or size (2 a/c rigs) got the 5500k higher end units and a power management system to shift loads. 3) the larger rigs with 2 a/c’s plus other big loads (res. fridges, etc.) got the 7500k units.

My current rig has a 10Kw gen. Previous rigs had a 12.5Kw and a 20Kw, the big one had a 220vac cooktop and dryer. And 4 air conditioners. And a buddy plug to plug another motorhome into my power.

Basic sizingOne A/C unit 4000 wattTwo A/C units min. 5000 watts.More A/C units, add 2000 watts per unit.

Use this link for a generic guide to 120 amp specs for appliances. It is generic but gets pretty close for the appliances.One misconception about Gensets is, they are NOT at the supposed amp the model suggests. IE--- a 5500 is about 46 amps and a 7500 is about 64 amps. People think the "55" or the "75" or "70" in the model number is the AMP total of the Genset. It is not. So you take the total amps the Genset supplies and take the chart to determine how much load the Genset can hold. Doughttps://www.facebook.com/lloydstrailersales/posts/754472354576047

Generator size | Good Sam Community

tropical36
Explorer
May 24, 2018
mikemc53 wrote:
We have been looking at used Class A coaches and it got me thinking (very rare for me) about generator capacity and/or capability.

Many of the coaches have a 5000 watt generator and some have 5500 up to 7500. It only makes sense that the larger ones have more capacity but my question runs to actual manufacturer or industry specs. Will the smaller (5K or less) units run the coach appliances well enough or were there a lot of them put out with under capacity gennies? I know this depends upon what the coach has, appliance-wise, but, in general, were most coaches made with enough gen capacity or are there a lot out there with under-powered gens?

I have been asking a lot of questions and will probably have many more but it looks like we are going to be seriously looking at used (older) coaches as the year unfolds.

Thanks gang.

Haven't seen 5.0, but there's a lot of 5.5KW out there, in the 30amp coaches. These are 45amp units, so has at least 15amps more available than the shore power. It accomplishes this by providing a separate 20amp feeder breaker on the genset itself, for the rear ac.
They only get larger from there and even with our 50amp coach, the 7.5KW quiet diesel gen. will run all that's necessary and even though a 10KW is closer to the industry standard now. Others have much larger units and especially with the all electrics out there, these days.
MrWizard
Moderator
May 24, 2018
I think it's more about the Mfg costs, than anything else
We had a 32 ft pace arrow with 30 amp service and 6500w Onan

We had a 31 ft komfort with a 5000w Onan 30 amp service

And a 34ft DP with a 50 amp service and a 6200w LP Onan

In the first to cases the generator supplied more power than shore power
With the DP, 50 amp shore power was larger than the generator

And I think the current trend with Mfg , is to make them pedistal queens with small generators unless they are large luxury coaches
turbojimmy
Explorer
May 24, 2018
Mine has a 6500-watt (50 amp @ 120V) generator. Like someone else said, the size of the generator depends on how the rig is optioned out. My shore power is only 30A so I can only run the front A/C unit. With the generator I can run both the front and rear. I bring all of the comforts of home (Keurig, toaster, hair driers (for the womens), etc.) to our annual NASCAR trip (which is totally off the grid) and the generator does fine. Have I tried to run everything at once? Heck no. But 5,000+ is plenty to run whatever you want - just not all at the same time.
dougrainer
Nomad
May 24, 2018
wa8yxm wrote:
I have two A/C's electric water heater and the usual complement of Fridge and TV's and such.. Plus an 80 amp converter. My 5500 has power to spare In fact when the need arises I will daisy chain one or two more RV's

3rd Ac would need a bigger Genny.

80 amp converter is the DC amps, not the AC amp draw which is 2 to 7 amps AC draw. Doug
wolfe10
Explorer
May 24, 2018
dougrainer wrote:
Use this link for a generic guide to 120 amp specs for appliances. It is generic but gets pretty close for the appliances.
One misconception about Gensets is, they are NOT at the supposed amp the model suggests. IE--- a 5500 is about 46 amps and a 7500 is about 64 amps. People think the "55" or the "75" or "70" in the model number is the AMP total of the Genset. It is not. So you take the total amps the Genset supplies and take the chart to determine how much load the Genset can hold. Doug

https://www.facebook.com/lloydstrailersales/posts/754472354576047

Correct. The numbers are for WATTS of output.

So, 46 amps times 120 volts= 5500 watts

And, 64 amps times 120 volts= 7500 watts

Yes, they rounded off the numbers-- a model number of 7680 probably did not make marketing sense.
wa8yxm
Explorer III
May 24, 2018
I have two A/C's electric water heater and the usual complement of Fridge and TV's and such.. Plus an 80 amp converter. My 5500 has power to spare In fact when the need arises I will daisy chain one or two more RV's

3rd Ac would need a bigger Genny.
dougrainer
Nomad
May 24, 2018
Use this link for a generic guide to 120 amp specs for appliances. It is generic but gets pretty close for the appliances.
One misconception about Gensets is, they are NOT at the supposed amp the model suggests. IE--- a 5500 is about 46 amps and a 7500 is about 64 amps. People think the "55" or the "75" or "70" in the model number is the AMP total of the Genset. It is not. So you take the total amps the Genset supplies and take the chart to determine how much load the Genset can hold. Doug

https://www.facebook.com/lloydstrailersales/posts/754472354576047
enblethen
Nomad
May 24, 2018
Basic sizing
One A/C unit 4000 watt
Two A/C units min. 5000 watts.
More A/C units, add 2000 watts per unit.
folivier
Explorer
May 24, 2018
My current rig has a 10Kw gen. Previous rigs had a 12.5Kw and a 20Kw, the big one had a 220vac cooktop and dryer. And 4 air conditioners. And a buddy plug to plug another motorhome into my power.
JaxDad
Explorer III
May 24, 2018
There seems to 3 different choices, for 3 different reasons, in deciding what generator got built in.

1) the smaller or entry level units got the venerable but pretty utilitarian 4k unit.

2) the next step up in units, either in quality or size (2 a/c rigs) got the 5500k higher end units and a power management system to shift loads.

3) the larger rigs with 2 a/c’s plus other big loads (res. fridges, etc.) got the 7500k units.