2021 Ac has soft start

[mexmahon]

The spike in amps drawn on startup is very quick and most Amp meters will not detect the peak amp draw and in most cases will calculate or average it out and give you a misinformed reading that is much lower than the actual peak amp draw that occurred. You almost need an Oscilliscope to capture it because it happens so quickly. If you are getting a reading of 32 amps instantaneously on your amp gauge, the true peak draw is likely much closer to 50 amps or so. Most 2200W or larger generators will appear to handle this instantaneous spike since it occurs too quick for the overload circuit to kick in. But it is very hard on the compressor if it is not receiving the required amps needed to properly kick start the compressor. You may not have an issues right away but it is likely going to shorten the life of the compressor.

The Easy Start reduces the needed amps to start the compressor by starting the compressor in multiple stages which according to Micro-Air, does not harm the compressor and reduced the starting amps by 45-60% on average.

So the moral of the story is just because your generator can run your AC (or AC circuit at your house using a long extension cord with inappropriate gauge of wire resulting in line loss) without faulting out or tripping a breaker doesn't mean it isn't causing harm to the compressor over the long term. You should check the actual manufacturer's specs to see the maximum amp draw needed for your AC unit (not the running amp requirement) and make sure you can supply that amount of current. Some manufacturer's will not list this in their documentation and lead you to believe that your 13.5K BTU AC only draws 13.1amps which is misleading. As you can see from the example below, this AC uses an average of 1400 running watts (11.66 amps) under A.R.I. standard test conditions but this goes up as the outside temperatures go up. In comparison, it uses 1800 watts (15amps) in desert conditions. These values are based on a constant 120VAC supply source.

So if your generator or home power source is putting out something other than 120VAC, the lower the supply voltage, the higher the amp draw required.

EXAMPLEWattage = Voltage X Amperage) The 13.5K BTU Coleman MACH AC unit shown below uses an average of 1400 running watts (11.66 amps) in normal conditions and 1800 watts (15amps) in desert conditions. If your power source (i.e. generator or home power outlet with long under-rated extension cord) is only putting out 110VAC, you now effectively need 12.7 or 16.4amps respectively to operate your AC. You can see how this is putting you dangerously close to the threshold for a 15amp breaker or even a 20 amp breaker if you have other devices running or your inverter is trying to charge your batter etc...as well as your 2200W generator rated for 1800W continuous use.


Also, a key metric on this spec sheet that is most commonly overlooked is the Compressor Locked Rotor Amps. This particular AC unit needs 50.5 amps at compressor startup to properly fire up the compressor! This is that magic number we see instantaneously on our amp meters that I mentioned above. But since it happens so quickly, it typically doesn't error out the generator or trip our 15amp breaker at home, but is indicative of the labored sound the compressor makes when it starts up when it isn't receiving the required amperage needed to properly fire up the compressor. The hard start capacitor on most units is used to offset this instantaneous amp draw on startup but can only provide this "boost" for a very short period of time (milliseconds). So if your generator stumbles during AC compressor startup, it is an indicator that it is having a difficult time providing the required amps needed to start up your AC unit. (remember Wattage = Voltage X Amperage. So if your generator stumbles and your voltage drops, your amperage requirement just went up). You can physically see this if you have a digital voltage gauge on your generator or put a meter on your wall outlet at home as you will see your voltage drop. As I stated above, it will most likely still start the compressor and it will run fine once it has started but it is slowly damaging the compressor each time it has to restart the compressor. And over time (maybe 6 months...maybe 2 years...maybe even longer) it will result in a premature compressor failure. The EasyStart reduces the required Compressor Locked Rotor Amps by around 45-60%. This means you no longer need 50.5amps on startup but rather somewhere around 20-27amps.

So the takeaway is don't just think that because your AC starts up and your generator doesn't fault out that you are good to go. Or that you are fine running your AC on your 15amp outlet at home with a 50ft standard duty extension cord just because it doesn't trip the breaker. Do your homework and see what the manufacturer's specs are for your AC unit and then plan accordingly with the appropriate sized generator or extension cord when on shore power.

Attachment 35533

Hey Jeff,
Also like the detailed answer. My question is with my 15k unit and 59 locked rotor amps puts me at over 7000w at start up. Is it true to say most all people running with generators out there, or inadequate shore power are slowing wearing down their AC compressors prematurely? Seems the only solution is a soft start. And if this is the norm out there with AC units why in the ^%@! wouldn't the manufacturer just put the dang soft starts in from the get go. Thanks again for you info.

[mexmahon]

The spike in amps drawn on startup is very quick and most Amp meters will not detect the peak amp draw and in most cases will calculate or average it out and give you a misinformed reading that is much lower than the actual peak amp draw that occurred. You almost need an Oscilliscope to capture it because it happens so quickly. If you are getting a reading of 32 amps instantaneously on your amp gauge, the true peak draw is likely much closer to 50 amps or so. Most 2200W or larger generators will appear to handle this instantaneous spike since it occurs too quick for the overload circuit to kick in. But it is very hard on the compressor if it is not receiving the required amps needed to properly kick start the compressor. You may not have an issues right away but it is likely going to shorten the life of the compressor.

The Easy Start reduces the needed amps to start the compressor by starting the compressor in multiple stages which according to Micro-Air, does not harm the compressor and reduced the starting amps by 45-60% on average.

So the moral of the story is just because your generator can run your AC (or AC circuit at your house using a long extension cord with inappropriate gauge of wire resulting in line loss) without faulting out or tripping a breaker doesn't mean it isn't causing harm to the compressor over the long term. You should check the actual manufacturer's specs to see the maximum amp draw needed for your AC unit (not the running amp requirement) and make sure you can supply that amount of current. Some manufacturer's will not list this in their documentation and lead you to believe that your 13.5K BTU AC only draws 13.1amps which is misleading. As you can see from the example below, this AC uses an average of 1400 running watts (11.66 amps) under A.R.I. standard test conditions but this goes up as the outside temperatures go up. In comparison, it uses 1800 watts (15amps) in desert conditions. These values are based on a constant 120VAC supply source.

So if your generator or home power source is putting out something other than 120VAC, the lower the supply voltage, the higher the amp draw required.

EXAMPLEWattage = Voltage X Amperage) The 13.5K BTU Coleman MACH AC unit shown below uses an average of 1400 running watts (11.66 amps) in normal conditions and 1800 watts (15amps) in desert conditions. If your power source (i.e. generator or home power outlet with long under-rated extension cord) is only putting out 110VAC, you now effectively need 12.7 or 16.4amps respectively to operate your AC. You can see how this is putting you dangerously close to the threshold for a 15amp breaker or even a 20 amp breaker if you have other devices running or your inverter is trying to charge your batter etc...as well as your 2200W generator rated for 1800W continuous use.


Also, a key metric on this spec sheet that is most commonly overlooked is the Compressor Locked Rotor Amps. This particular AC unit needs 50.5 amps at compressor startup to properly fire up the compressor! This is that magic number we see instantaneously on our amp meters that I mentioned above. But since it happens so quickly, it typically doesn't error out the generator or trip our 15amp breaker at home, but is indicative of the labored sound the compressor makes when it starts up when it isn't receiving the required amperage needed to properly fire up the compressor. The hard start capacitor on most units is used to offset this instantaneous amp draw on startup but can only provide this "boost" for a very short period of time (milliseconds). So if your generator stumbles during AC compressor startup, it is an indicator that it is having a difficult time providing the required amps needed to start up your AC unit. (remember Wattage = Voltage X Amperage. So if your generator stumbles and your voltage drops, your amperage requirement just went up). You can physically see this if you have a digital voltage gauge on your generator or put a meter on your wall outlet at home as you will see your voltage drop. As I stated above, it will most likely still start the compressor and it will run fine once it has started but it is slowly damaging the compressor each time it has to restart the compressor. And over time (maybe 6 months...maybe 2 years...maybe even longer) it will result in a premature compressor failure. The EasyStart reduces the required Compressor Locked Rotor Amps by around 45-60%. This means you no longer need 50.5amps on startup but rather somewhere around 20-27amps.

So the takeaway is don't just think that because your AC starts up and your generator doesn't fault out that you are good to go. Or that you are fine running your AC on your 15amp outlet at home with a 50ft standard duty extension cord just because it doesn't trip the breaker. Do your homework and see what the manufacturer's specs are for your AC unit and then plan accordingly with the appropriate sized generator or extension cord when on shore power.

Attachment 35533

Hey Jeff,
Also like the detailed answer. My question is with my 15k unit and 59 locked rotor amps puts me at over 7000w at start up. Is it true to say most all people running with generators out there, or inadequate shore power are slowing wearing down their AC compressors prematurely? Seems the only solution is a soft start. And if this is the norm out there with AC units why in the ^%@! wouldn't the manufacturer just put the dang soft starts in from the get go. Thanks again for you info.

[Heavysledz]

Hey Jeff,
Also like the detailed answer. My question is with my 15k unit and 59 locked rotor amps puts me at over 7000w at start up. Is it true to say most all people running with generators out there, or inadequate shore power are slowing wearing down their AC compressors prematurely? Seems the only solution is a soft start. And if this is the norm out there with AC units why in the ^%@! wouldn't the manufacturer just put the dang soft starts in from the get go. Thanks again for you info.

Please note that the locked rotor starting amps is only needed for a few seconds and on most OEM units their is a "start capacitor" or "hard start capacitor" in the system that is used to provide SOME (not all) of the required amperage boost needed to jumpstart the compressor. The problem is the output of the start capacitor is very short (measured in milliseconds) and only "assists" in starting the compressor. To further complicate things, the power required to start the compressor changes as the environmental conditions change. For example: As I stated in my previous response, as the outside air temperature increases, the rated operating wattage goes up exponentially. The same hold true for the starting wattage. However, the output of the "start capacitor" or "hard start capacitor" is fixed so the more extreme the conditions get, the more power that is required to start the compressor. As you can see, this puts everything into that grey area since nobody truly knows how many amps you truly need to provide during compressor startup unless you have the right equipment (oscilloscope) that can measure this draw realtime and is fast enough to catch it and even then, the requirements are constantly changing baed on environmental conditions.

The only upgrade that I am aware of that is currently available that addresses this is the Micro-Air EasyStart as it measures the amp draw during start up and uses a proprietary algorythm to calculate how much amperage is needed and for how long at several points during the compressor startup cycle (a few seconds) and spreads out the amp draw across this period of time resulting in significantly less amps required at any given time.....the end result is a lower power requirement for compressor startup (i.e. locked rotor load rating)....this does nothing for the rated "running watts" needed to keep the compressor running once it is started though.

So it is difficult to answer you question, with either a yes/no answer given the variables I have touched on above. The safe answer is to ensure you are not operating at the very top end of your power supply source's rated capability and that you have some margin in your supplied capacities versus your loads. Meaning don't think because you have an A/C unit that is rated for 1400 running watts and you are using a 2200 watt rated generator (1800 watts continuous use rated) that you have plenty of margin. That margin get's quickly depleted when you take into account all of the "variables".

Example: Your 1400 running watts rated AC unit may require up to 1800 watts if the outside air temps are high. This alone puts you at or above the maximum rated continuous running wattage out put of your generator before you then add in all of the other power requirements you are putting on your generator at the same time such as your onboard power inverter supplying all of your DC powdered devices as well as the built-in DC charger that is trying to keep your battery(s) charged while on an AC power source.

The best advice I could give is if your RV is equipped to work off of a 30amp power source and you want to use a generator to augment the use of shore power that you simply purchase a generator or multiple generators and a parallel kit that will provide a rated 30 amps (3600 Watts) of continuous power as a minimum requirement. This will allow you run things in your RV just as if you are on shore power with all of the active load protections in place in the power control panel (i.e. circuit breakers and fuses). I have learned over the years that even though the smaller 2200 watt generators can/will run many AC units that it is putting a very heavy load on the generator making it run at a much higher duty cycle...this translates into more fuel consumption and higher decibel levels as the generator is under heavy loads. A 4200 watt generator (3600 running watts) will very likely be able to run anything in the trailer and remain in "ECO" mode which translates into fuel savings as well as lower decibels. The generator will also likely last longer as it is being run at a much lower duty cycle.

Again, I hope this helps put things into perspective for you.

[JM0397]

On our 310 GK-R, I was able to fire up each AC independently the other day, on a standard extension cord shore power plugin. I'm not sure if the outlet at our storage facility is 15 or 20amp, but it didn't blow.
I even switched on the fridge with the main AC to see what would happen (we need to run the fridge the night before heading out) and it didn't pop the breaker.
This is very helpful for us, especially in the NC summers! Our Purple gel mattress holds a lot of heat, so first night out last time was a warm evening, even with the AC cranked down. Now I can fire up the bedroom AC the night before and easier sleeping first night out!

[Wicked ace]

Please note that the locked rotor starting amps is only needed for a few seconds and on most OEM units their is a "start capacitor" or "hard start capacitor" in the system that is used to provide SOME (not all) of the required amperage boost needed to jumpstart the compressor. The problem is the output of the start capacitor is very short (measured in milliseconds) and only "assists" in starting the compressor. To further complicate things, the power required to start the compressor changes as the environmental conditions change. For example: As I stated in my previous response, as the outside air temperature increases, the rated operating wattage goes up exponentially. The same hold true for the starting wattage. However, the output of the "start capacitor" or "hard start capacitor" is fixed so the more extreme the conditions get, the more power that is required to start the compressor. As you can see, this puts everything into that grey area since nobody truly knows how many amps you truly need to provide during compressor startup unless you have the right equipment (oscilloscope) that can measure this draw realtime and is fast enough to catch it and even then, the requirements are constantly changing baed on environmental conditions.

The only upgrade that I am aware of that is currently available that addresses this is the Micro-Air EasyStart as it measures the amp draw during start up and uses a proprietary algorythm to calculate how much amperage is needed and for how long at several points during the compressor startup cycle (a few seconds) and spreads out the amp draw across this period of time resulting in significantly less amps required at any given time.....the end result is a lower power requirement for compressor startup (i.e. locked rotor load rating)....this does nothing for the rated "running watts" needed to keep the compressor running once it is started though.

So it is difficult to answer you question, with either a yes/no answer given the variables I have touched on above. The safe answer is to ensure you are not operating at the very top end of your power supply source's rated capability and that you have some margin in your supplied capacities versus your loads. Meaning don't think because you have an A/C unit that is rated for 1400 running watts and you are using a 2200 watt rated generator (1800 watts continuous use rated) that you have plenty of margin. That margin get's quickly depleted when you take into account all of the "variables".

Example: Your 1400 running watts rated AC unit may require up to 1800 watts if the outside air temps are high. This alone puts you at or above the maximum rated continuous running wattage out put of your generator before you then add in all of the other power requirements you are putting on your generator at the same time such as your onboard power inverter supplying all of your DC powdered devices as well as the built-in DC charger that is trying to keep your battery(s) charged while on an AC power source.

The best advice I could give is if your RV is equipped to work off of a 30amp power source and you want to use a generator to augment the use of shore power that you simply purchase a generator or multiple generators and a parallel kit that will provide a rated 30 amps (3600 Watts) of continuous power as a minimum requirement. This will allow you run things in your RV just as if you are on shore power with all of the active load protections in place in the power control panel (i.e. circuit breakers and fuses). I have learned over the years that even though the smaller 2200 watt generators can/will run many AC units that it is putting a very heavy load on the generator making it run at a much higher duty cycle...this translates into more fuel consumption and higher decibel levels as the generator is under heavy loads. A 4200 watt generator (3600 running watts) will very likely be able to run anything in the trailer and remain in "ECO" mode which translates into fuel savings as well as lower decibels. The generator will also likely last longer as it is being run at a much lower duty cycle.

Again, I hope this helps put things into perspective for you.

I want to add that to check FLA-full load amps at start up you could use an analog ammeter with a dial and pointer. Or I know Fluke makes a modern meter to capture and record start up current draw but then you are getting into something that is a tool of a professional and we will never use.. As mentioned a digital multi meter will average over time and give a median current reading. An Oscilloscope is not a good way to measure current as it cannot do it directly. It can be use used in conjunction with a your digital multi-meter a little understanding of Ohm's law and a few resistors.
https://www.homedepot.com/p/Gardner-...-500/202867879

Or you could look up the data sheet and it will tell all you need to know: https://www.airxcel.com/DesktopModul...sheet_1012.pdf