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Author Topic: Air Conditioner amperage draw at low voltages  (Read 13119 times)

Chris Hindle

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Re: Air Conditioner amperage draw increases at low voltages
« Reply #30 on: October 02, 2018, 12:32:55 PM »

Why hasn't anyone designed an interlocking switch/receptacle panel where the RV plug can't be connected or disconnected with the switch on?

It could be as simple as a switch handle that covers the receptacle and plug when on. I think every RV I've ever seen has a right-angle plug, so it shouldn't be too difficult.
Sell it as a weather cover. Open cover, power is off. Close cover, .....
Chris.
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Ya, Whatever. Just throw a '57 on it, and get off my stage.

Jay Barracato

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Re: Air Conditioner amperage draw at low voltages
« Reply #31 on: October 02, 2018, 07:42:58 PM »

Sell it as a weather cover. Open cover, power is off. Close cover, .....
Chris.
Because the RV crowd and gadget industry will immediately start selling some "convenience" device to bypass it.

Sent from my Moto Z (2) using Tapatalk

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Tim McCulloch

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Re: Air Conditioner amperage draw at low voltages
« Reply #32 on: October 02, 2018, 11:20:22 PM »

Because the RV crowd and gadget industry will immediately start selling some "convenience" device to bypass it.

Sent from my Moto Z (2) using Tapatalk

I think guys just want gadget bragging rights around the camp fires.  "Hey guys, check this out... lets you plug in to those fancy self-closing boxes!"
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"If you're passing on your way, from Palm Springs to L.A., Give a wave to good ol' Dave, Say hello to progress and goodbye to the Moonlight Motor Inn." - Steve Spurgin, Moonlight Motor Inn

Chris Hindle

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Re: Air Conditioner amperage draw at low voltages
« Reply #33 on: October 03, 2018, 08:23:05 AM »

I think guys just want gadget bragging rights around the camp fires.  "Hey guys, check this out... lets you plug in to those fancy self-closing boxes!"

Ya, who cares about "safety", "Fire" and "not killing people" once beer is involved....
Oh well.
If it were easy, it would already be done.
Chris.
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Stephen Swaffer

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Re: Air Conditioner amperage draw at low voltages
« Reply #34 on: October 03, 2018, 01:21:51 PM »

So the smallest service I can legally put in a home is 100 amps-but ignoring that limitation, if I figure a service based on an oven, hot water heater, and AC unit roughly half the size of a house then do rest of my required calculations I come up with a required service size of somewhere around 60 amps-and that will be connected to the POCO through (hopefully) torqued lugs. And service conductors sized for 3% voltage drop.

Is it any wonder that RV's on 30 or 50 amp receptacles with a long cord plugged into tired receptacles from X number of plugins each summer, abused by weather 24/7 and multiple thermal cycles have issues with plugs melting down?
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Tim McCulloch

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Re: Air Conditioner amperage draw at low voltages
« Reply #35 on: October 03, 2018, 02:16:24 PM »

So the smallest service I can legally put in a home is 100 amps-but ignoring that limitation, if I figure a service based on an oven, hot water heater, and AC unit roughly half the size of a house then do rest of my required calculations I come up with a required service size of somewhere around 60 amps-and that will be connected to the POCO through (hopefully) torqued lugs. And service conductors sized for 3% voltage drop.

Is it any wonder that RV's on 30 or 50 amp receptacles with a long cord plugged into tired receptacles from X number of plugins each summer, abused by weather 24/7 and multiple thermal cycles have issues with plugs melting down?

I'm surprised there aren't more problems at the RV end.  Folks with shore power on retracting reels have little idea of what can and do go wrong.  Hot & loaded connection of CS-series at the coach.  Vibration-loosened lugs and terminals in auto transfer switches, bad relay contacts in ATS; loose connections at inverter/converter/charger...  There's a lot of manual maintenance to be done on RVs and there are plenty of owners who get surprised by just how much of they need to do themselves.
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"If you're passing on your way, from Palm Springs to L.A., Give a wave to good ol' Dave, Say hello to progress and goodbye to the Moonlight Motor Inn." - Steve Spurgin, Moonlight Motor Inn

Mike Sokol

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Re: Air Conditioner amperage draw at low voltages
« Reply #36 on: October 05, 2018, 05:28:20 AM »

There's a lot of manual maintenance to be done on RVs and there are plenty of owners who get surprised by just how much of they need to do themselves.

The big difference between your brick house and your RV is that the RV bounces down the road thousands of miles every year and plugs into perhaps dozens of different power services, while your brick house electrical system is one and done.

Tim McCulloch

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Re: Air Conditioner amperage draw at low voltages
« Reply #37 on: October 05, 2018, 11:09:28 AM »

The big difference between your brick house and your RV is that the RV bounces down the road thousands of miles every year and plugs into perhaps dozens of different power services, while your brick house electrical system is one and done.

Both of my grandfathers were farmers so I became acquainted with vibration and impact issues at a young age.  It's younger RV owners who will be surprised - those owners who can't change the tire on their car or know where the crankcase dipstick is... or why you'd care.
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"If you're passing on your way, from Palm Springs to L.A., Give a wave to good ol' Dave, Say hello to progress and goodbye to the Moonlight Motor Inn." - Steve Spurgin, Moonlight Motor Inn

Mark Cadwallader

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Re: Air Conditioner amperage draw at low voltages
« Reply #38 on: October 05, 2018, 04:16:11 PM »

Both of my grandfathers were farmers so I became acquainted with vibration and impact issues at a young age.  It's younger RV owners who will be surprised - those owners who can't change the tire on their car or know where the crankcase dipstick is... or why you'd care.

Why fix it if you can just trade it in on a new (bigger/better) one?
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Steve-White

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Re: Air Conditioner amperage draw at low voltages
« Reply #39 on: December 22, 2018, 06:23:53 PM »

It will be interesting to see what happens to the amperage as the voltage drops down to 93 volts, which is the lowest reported campground voltage so far. It obviously can't be linear, with a 50% reduction in voltage causing a 50% increase in amperage. But it's possible that dropping the voltage down into the mid 90's could increase the amperage by 20% or so, and that will probably lead to a lot of internal heat buildup in the compressor.

To sum in up, it's about watts Mike.  Watts in, less the heat dissipation or power loss (motor efficiency) = horsepower out.  To compensate for voltage drop, the current will increase in general terms - to maintain power output of the motor.  They are designed to run within an optimal range - too far out with high/low voltage or frequency and things go china syndrome.
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Re: Air Conditioner amperage draw at low voltages
« Reply #39 on: December 22, 2018, 06:23:53 PM »


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