The new 1500W Inverter can not open garage door

Thread Starter

LAOADAM

Joined Nov 21, 2018
166
I have new 1500W Inverter can not drive a 1/2 HP garage door, why?
I used two MTP-78 batteries in parallel, each of them has 800 Cold Cranking Amps (CCA).
post-26.JPG
 

drc_567

Joined Dec 29, 2008
711
... Are you able to manually raise the door with a minimum effort? If there is a coiled spring assembly, ... overhead ... then it is possible that the counterbalance force ... to raise the door ... requires adjustment.
 

Reloadron

Joined Jan 15, 2015
4,508
Was the garage door motor previously run on an inverter? Most inverters output a modified sine wave and motors like those used for a garage door opener don't like a modified sine wave. A typical 120 VAC 1/2 HP garage door motor draws about 6.5 amps, give or take depending on the motor. However, on start the current draw (inrush current) is much greater which may cause the inverter to drop offline. So there are a few possibilities. If possible can you try standard household (sine wave) current and see if the door works?

Ron
 

Reloadron

Joined Jan 15, 2015
4,508
Yes, the door can run easily by Line power. even manually.
Well, rhen we know the door is functional when running on mains voltage which is a pretty pure sine wave. We know that a 1/2 HP motor running on 120 VAC will draw just about 6.5 Amps so if we multiply that 6.5 amps * the 120 VAC we get a power draw of about 780 Watts which is way below your inverter's max power rating of 1500 watts. Motors like what you have typically have a high "inrush current" . While inrush current has a peak current value, the term “Inrush Current” is commonly used to describe the current that is required to energize an AC powered device or product when first applying voltage and power to it. This is especially true for inductive loads such as transformers, Inductors and electric motors. While only lasting for a split second that inrush current for a motor starting under load that current can be many times the motors normal run current.

So while it would appear a 120 VAC inverter capable of 1500 watts (12.5 amps) should easily run a 6.5 amp motor that is not always true. A smart inverter will immediately shut down when it sees an excessive load and your motor could have an inrush current as much as ten times the usual standard current, so as much as 65 amps at 120 VAC for a total of 7800 watts. Inverter detects it and immediately shuts down before motor current drops to the normal run current.

Another issue is most inexpensive inverters use a MSW (Modified Sine Wave) output waveform and not a TSW (True Sine Wave) output which many motors do not run well on or won't run on at all. If your inverter is not a TSW output that may compound the problem issues. The Inverter manual or data sheet should define the type AC output produced. So it's not always how many large AH batteries feed the inverter but what the inverter is actually capable of.

Ron
 

recklessrog

Joined May 23, 2013
988
Also be aware that a lot of inverters do not like inductive loads and the small print in the specs often gives a de-rating power when used with them.
A local mobile burger van was trying to eliminate using a petrol generator to run his lights and fridge, so bought a 1.5kW inverter. Although it would run a 1kW electric fan heater ok, it would shut down when trying to run the fridge that had a nominal 180W compressor. One reason was the high start current required, and the other was a note in the instructions that said "Not suitable for inductive loads such as fridges etc"
By searching around, he found one that was meant to run boat electrics, and although only 1kW, worked fine.
 

Reloadron

Joined Jan 15, 2015
4,508
I've used this inverter to run motors and AC units with great success for years.


http://www.xantrex.com/power-products/power-inverters/prowatt-sw.aspx
"The PROwatt SW Series feature True Sine-Wave AC output with 540, 900 and 1800 continuous watts respectively. With high surge capability, the PROwatt SW Series provides the necessary current to startup demanding electrical loads such as variable speed power tools, advanced electrical appliances, microwaves and much more. In addition to dual GFCI AC receptacles, the PROwatt SW Series include an innovative USB connection for providing power to most USB chargeable devices. The PROwatt SW Series offers many safety features not found in similar inverters. When equipped with a remote control, the PROwatt SW Series has the ability to provide automatic ignition lockout shutting down the inverter’s output when the vehicle’s ignition is not engaged".

Very nice inverter and a TSW output.

Ron
 

sghioto

Joined Dec 31, 2017
1,039
From the manufacturer of the MotoMaster 1500w:

Modified sine wave output form - compatible with most AC appliances (refer to appliance manufacturer to confirm compatibility)
SG
 

nsaspook

Joined Aug 27, 2009
6,279
"The PROwatt SW Series feature True Sine-Wave AC output with 540, 900 and 1800 continuous watts respectively. With high surge capability, the PROwatt SW Series provides the necessary current to startup demanding electrical loads such as variable speed power tools, advanced electrical appliances, microwaves and much more. In addition to dual GFCI AC receptacles, the PROwatt SW Series include an innovative USB connection for providing power to most USB chargeable devices. The PROwatt SW Series offers many safety features not found in similar inverters. When equipped with a remote control, the PROwatt SW Series has the ability to provide automatic ignition lockout shutting down the inverter’s output when the vehicle’s ignition is not engaged".

Very nice inverter and a TSW output.

Ron
It's works great but it won't give that great surge capacity without some huge DC wiring running 12vdc @ 300A+. I've got 4/0 gauge copper cables with 10-ton hydraulic crimped lugs for the DC feed connections to the battery bank, bank selector switch and inverter.

Example: Not cheap.
https://www.batterycablesusa.com/0000-gauge-battery-cable-with-ends-4-0-awg
 

Reloadron

Joined Jan 15, 2015
4,508
It's works great but it won't give that great surge capacity without some huge DC wiring running 12vdc @ 300A+. I've got 4/0 gauge copper cables with 10-ton hydraulic crimped lugs for the DC feed connections to the battery bank, bank selector switch and inverter.

Example: Not cheap.
https://www.batterycablesusa.com/0000-gauge-battery-cable-with-ends-4-0-awg
Good stuff never is cheap or I guess it would be cheap stuff. :) But the right good stuff you can rely upon.

Ron
 

nsaspook

Joined Aug 27, 2009
6,279
Good stuff never is cheap or I guess it would be cheap stuff. :) But the right good stuff you can rely upon.

Ron
I've dumpster dived lots of heavy copper wire over the years but it's hard to find today.


Wrong wire size is the #1 mistake when installing something like a 12vdc inverter for large surge loads. Almost any measurable wire resistance can drop the voltage at the inverter below the under-volt cutout point on 12vdc systems running AC induction motors causing a shutdown in milliseconds.

I see people using 10 gauge wire for 5 foot one-way distance DC cables. Yes, it will usually work for smaller resistive loads. Going overkill on wire gauge eliminates the voltage drop issue and going to a higher DC source voltage inverter reduces the peak current wiring gauge requirements.

https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=3.277&voltage=12&phase=dc&noofconductor=1&distance=5&distanceunit=feet&amperes=300&x=71&y=15
 

Reloadron

Joined Jan 15, 2015
4,508
I've dumpster dived lots of heavy copper wire over the years but it's hard to find today.


Wrong wire size is the #1 mistake when installing something like a 12vdc inverter for large surge loads. Almost any measurable wire resistance can drop the voltage at the inverter below the under-volt cutout point on 12vdc systems running AC induction motors causing a shutdown in milliseconds.

I see people using 10 gauge wire for 5 foot one-way distance DC cables. Yes, it will usually work for smaller resistive loads. Going overkill on wire gauge eliminates the voltage drop issue and going to a higher DC source voltage inverter reduces the peak current wiring gauge requirements.

https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=3.277&voltage=12&phase=dc&noofconductor=1&distance=5&distanceunit=feet&amperes=300&x=71&y=15
So, you were out in my garage and took a picture? I tend to overkill with wire gauge. Watched a guy set his car on fire using zip cord (18 AWG lamp cord) to connect a 500 watt audio amp. Ran it through the firewall and under carpeting to the trunk. Was like det cord. :)

Ron
 

nsaspook

Joined Aug 27, 2009
6,279
So, you were out in my garage and took a picture? I tend to overkill with wire gauge. Watched a guy set his car on fire using zip cord (18 AWG lamp cord) to connect a 500 watt audio amp. Ran it through the firewall and under carpeting to the trunk. Was like det cord. :)


Ron
It helps to fuse for wire size at the source.


I'm still trying to find something to use this jumper (Diesel Locomotive Cable) on.:eek: The wire loop about the big cable is 4/0.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
166
Well, the 'Inrush Current' should make the point, how to do then?
there is a quite large start capacitor in side the box.
Should I added a H Bridge and PWM?
 

Reloadron

Joined Jan 15, 2015
4,508
NO, you need to know if the inverter outputs a MSW or TSW out and if the motor will run on a MSW. With the AC a capacitor won't matter and H Bridges and PWM apply to DC motors.

Ron
 

Reloadron

Joined Jan 15, 2015
4,508
Oh yeah, that's right. You called it.

This is not going to happen with the existing inverter. There is no magic bullet I can see.

Ron
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
166
Yeah, looks I did a stupid thing.
My two almost new batteries got bad, they was ~28 V drop to ~21V after hooked to the inverter. and they can't be charged now, I mean just got to ~23V after more than 11 hours charging.
 

Reloadron

Joined Jan 15, 2015
4,508
You lost me? From your original post:
I used two MTP-78 batteries in parallel, each of them has 800 Cold Cranking Amps (CCA).
Those are 12 volt batteries and placing two 12 volt lead acid batteries in parallel will yield about 12 volts, closer to 12.6 volts on charged batteries. Your inverter is designed for a 12 volt input. so where did this come from?
My two almost new batteries got bad, they was ~28 V drop to ~21V after hooked to the inverter. and they can't be charged now, I mean just got to ~23V after more than 11 hours charging.
Ron
 
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