use 12vDC output from generator to power pure sine inverter?

[scajjr2]

After having to use our generator for the first time (had it for 5 yrs, run it every couple months) Sun & yesterday (power was only out for 15hrs, lucky compared to those in central NH and SE Maine) I was wondering about using it's 12vDC output to power an inverter to run the P43 in case we ever have to use it during heating season.

6000w generator hooked into a Reliance Pro-Tran 10 circuit transfer switch, could easily add another outside box to connect the 12vDC to with another connection inside to hook up to inverter.

Sam

 

[blades]

Sam if the genny is already on an automatic transfer system then why would you need an additional inverter, as the gen output is already being inverted / suppied at 110/30 volts ac or 220/ 40 ac to power those 10 circuits mentioned. aAsurge suppressor would be a good idea though.

 

[scajjr2]

It's a manual transfer and not a generator w/inverter output so was concerned about dirty AC.

Sam

 

[jbomb7124@gmail.]

Don’t be. It’ll be fine but as stated a surge suppressor is not a bad idea. I run my whole house on my 6000w harbor freight genii. For what it’s worth I’m a union electrician and have taken many classes on power generation dc ac theory . Your stoves board has a dc rectifier that converts ac to dc then uses dc for the electronics.. your motors may or may not use ac current but they don’t care about your sine wave either. These systems are all pretty basic. And most of not all generators produced these days put out pretty good power.


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[peakbagger]

I am a fan of running dirty power through a UPS. The problem is other uses of the generator for things like well pumps can really screw up the voltage when they kick on and off. An inverter is basically a UPS without a battery and sometimes the battery is needed to make up for a sag in voltage from the generator. A good UPS will filter out the surges and cover the load to the stove if you need to disconnect it from the generator. I do agree that most new power equipment is equipped to handle voltage surges compared to older gear. I have less faith than the prior poster on the power quality produced by a home generator. If running electronics, the newer style inverter generators are effectively doing what you are proposing.

 

[blades]

Around here the power coming in is worse than my genny.

 

[jbomb7124@gmail.]

Around here the power coming in is worse than my genny.

I’m 16 miles from 9 mile point “ a nuclear power plant .. actually 3 of them “ and if I scope my outlets it’s 58 hertz and the wave is rather jagged . My generator runs at 59 with a square wave . Plus or minus 2 volts when the fridge or central air kick off or on . I’ve seen far worse from the grid .. Syracuse’s power is particularly bad. From what the lineman at grid tell me they have a rather challenging time making clean power due to the prevalence of led lights in the city. The high number of diodes are reaking havoc on the neutral currents. Granted an ac motor will generate slightly more heat with a square wave then a pure wave but it’s highly unlikely to have a great enough impact to shorten the lifespan.. possible but unlikely. Just my 2 cents based on my exp. I’ll continue running my home on my generator as I have sense I bought the place when the power fails ..


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[scajjr2]

I have a APC UPS that the stove is plugged into anyway, got it before we ordered the P43 back in 2013.

So running an inverter off the 12vDC of the generator would be more for my "peace of mind" vs actual dirty AC?

Sam

 

[peakbagger]

The dirty secret of UPS units is that most of the inexpensive units that homeowners would buy are not true sine wave output they actually are some very choppy looking modified square waves. This site is a bit technical and a bit confusing but has a lot of waveforms from various units https://www.hardwareinsights.com/database-of-ups-output-waveforms/4/#APC-Schneider-Electric-other. UPS units were designed to feed electronics and computers and both typically use switched mode power supplies that can handle the choppy input waveform and widely varying input voltage. The output and frequency of a UPS is usually consistent with pretty solid voltage limits, its just that the waveform is choppy. The choppy waveforms can heat up motors, they will run but it can reduce the life of the motors as the windings take a beating.

Generally a cheap UPS is running in bypass mode which means its just passing whatever power is coming in off the line. It most likely will pass a narrow range of high and low voltage conditions before it switches to the batteries. Once its on batteries then the choppy waveform kicks in. A motor is actually not that unhappy with some varying frequency that a cheap generator will put out, its far less happy with a choppy waveform.

Hard to make generalities but the best option is run the stove off a generator running 24/7 with a UPS. The less preferable method is running the generator intermittently charging up the UPS and then running off the UPS as that exposes the motor to the choppy waveform for longer periods.

If someone is really paranoid about long extended outages than its time to start looking at off grid technology with large battery banks and true sine wave inverters. If you want to believe the hype, feel free to get in line for a couple of Tesla Power wall 2 batteries and bite the bullet and install solar panels. Around 30 K will cover it with Uncle Sam kicking in 30% and then you get the long term benefits of reduced power costs. I expect the better option is spend a bit more money for a name brand inverter generator compared to a home cheapo special. An inverter generator is going to cut your gas usage during an outage and the output waveform is going to be a true sine wave so the motors will be happy. The other option is if you have a deep well is to consider switching to constant pressure variable speed pump controller as that is going to cut down on the size generator you would need to run as generally a deep well pump is the biggest surge load in a house.