1000w pure sine wave inverter with automatic on/off ("standby" mode, "sleep" mode, etc)

pioneer · February 2017

I have been reading the forum for a couple weeks, what a resource! Now this is my first post.

I am trying to plan out a solar power system for a short bus I am converting into a camper. I will use the system to power a few things namely: low wattage DC LED lights, charge phone and tablet, run converted chest freezer to fridge. I have read a couple of results from people that have done the chest freezer conversion and for the size freezer I am going to convert, these converted freezer are only costing people .2-.3kwh a day!

I need a 1000w inverter so I can handle the start up surge of the converted freezer. I have been looking at some of the most reviewed 1000w psw inverters such as the Sunforce 11240, Xantrex Prowatt sw1000, MicroSolar 1000w, Power Bright APS1000, and Renogy 1000w.

The inverter will really not need to be on that often throughout the day. I will only have my phones and tablet on the charger when charge is needed and the converter freezer will just need to be on when it kicks on multiple times throughout the day. Because of this I really want an inverter that has an automatic on/off (I have also heard this called standby mode and sleep mode). So my inverter will only be on for the couple of time a day the freezer kicks on and also of course for the limited time I will be using lights and chargers.

None of the inverters above have an automatic on/off listed in their manuals. So I am wondering if anybody knows of a 1000w pure sine wave inverter with this feature.

The basic components of the system I am planning will be
-200-250w mono panel
-20a mppt charge controller
-(2) 6V 225ah batteries wired in series
-1000w pure sine wave inverter

Thanks!

mcgivor · February 2017

Having experience with Cotek, the sleep mode requires a load greater than 15W to wake it up, this wattage is generally greater than a cell phone charger uses, my suggestion is to use a automotive cigarette lighter USB charger directly to the battery for this purpose.

An automatic on/off is something I've personally never heard of, just sleep or standby, it has to be alive to wake up, if it was dead it couldn't wake up, my theroy.

One observation, you may be seriously underestimating the freezer / refrigerators energy needs, without data on it's requirements can't be 100% sure but from experience, would guess it's much more than 0.2-0.3 Kwh, this would mean your proposed system would be undersized.

mike95490 · February 2017

https://www.victronenergy.com/inverters/phoenix-inverter-180va-1200va
The 800 & 1200 VA inverters have Search Mode.
But beware, some fridges reboot when the power fails, and may start up in a Defrost cycle or something less than desirable,
Search Mode = power failure, and you may hear a hum or buzz every 3 seconds as the inverter searches for a load

TenMile · May 2017

I have a very similar setup at an off-grid family cabin. I use a GoPower inverter that has a "Power Save" mode. When there is nothing drawing power, the inverter shuts itself down and draws roughly .1A/hr. We use it primarily for lights, Satellite TV and Internet (no fridge). I find that a single LED/CFL bulb does not have the power to actually kick the inverter to start -- 2 CFL bulbs do, and an incandescent bulb does -- the stated power requirement is 7W. Any kitchen appliances, hand tools, TV etc will all start fine.

For phone charging, what I'd recommend is to install a 12V cigarette lighter type adapter with a USB charger built into it. That way you can charge your phone on demand without having to use the inverter.

2manytoyz · May 2017

I actually have done a project similar to what you are trying to do. I'm using a wall-wart connect to a relay to power up the inverter when the grid goes down. You could use a thermostat, timer, etc., to do the same task. Details of how I modified my inverter is here: http://www.2manytoyz.com/autoinverter.html

I also have an older Prosine 1800W inverter. It has a Power Save feature. This only consumes 1.5 Watts/hr. Once every 2 seconds, the inverter sends out a pulse to detect if a load of 20 Watts or larger, has been applied. If so, the inverter comes online. When the 20+W load is removed, the inverter goes back into Power Save mode. Some of the smaller loads I would run from this inverter during a grid down event would lose power since the load is too light. This is why I did the mod in the link above.

My newer ProWatt SW2000 inverter does not have a Power Save feature. It's rated at 1800 Watts. I measured the idle current at 3.84 Watts/hr 92 Watts/day Note: Xantrex claims this model has an idle current of < 0.8A. I measured 0.32A. Details on my various inverter's idle current here: http://http//2manytoyz.com/noload.html

Any of you loads that can run from 12V, connect them directly. Don't convert your DC power to AC, then back to DC to charge them. Inefficient and unnecessary.

Good luck with your project!

706jim · May 2017

Where one should run 12 volt loads using the inverter is when the inverter is supplied by 24 or 48 volts. Tapping the battery to run these loads will lead to an uneven battery charge condition. My old Trace works great on the standby mode, but the last two years, I've run the inverter on all of the time to run undercounter LED lights and cell phone chargers. I figure the amount of energy I would save isn't significant particularly when I bump up the array size this summer.

myocardia · June 2017

2manytoyz said:
Any of you loads that can run from 12V, connect them directly. Don't convert your DC power to AC, then back to DC to charge them. Inefficient and unnecessary.

Indeed. You can run all of your loads on roughly what it will cost you to just idle a mid-sized inverter 24 hours/day. That includes refrigeration, as well...assuming you buy a DC refrigerator, of course. Our host sells them, btw: https://www.solar-electric.com/residential/solar-refrigerators-freezers.html

In a low-powered system, being 100% DC is way more efficient, and that goes double for mobile use, especially when there is not a lot of roof space for mounting panels, such as short buses, pickup campers, type B motorhomes*, and the like. For charging cell phones, laptops, and tablets, just buy one or two 12V female lighter sockets, and a couple of the 12V USB car chargers that you can buy from Amazon for $5-10 each. For fans, just search Amazon for "12V car fan". You can buy 12V fans for $15-30, and they are extremely efficient, compared to AC-powered fans, even if you ignore the inefficiencies of using inverters. Most of the 12V fans use only ~1A, which @ 12V is ~12-14 watts.**

To be clear, I'm not saying that using an inverter is always a bad idea. Most of us use inverters at our homes and/or on our large RVs, but we have thousands of square feet in which to mount solar panels at our homes, and upwards of twice the space to mount them on the larger RVs.

* Type B motorhomes are the ones with either a van or a pickup "frontend", and are pretty much always shorter than the type A motorhomes.

** Assuming we ignore the unefficient radiator fans-- which work great when just hooked directly to a 12V panel, btw.

edit: And to power 12V loads directly from a 24V battery bank, all that is needed is a voltage converter, which our host carries: https://www.solar-electric.com/residential/voltage-converters-switches.html

Lumisol · June 2017

> @mcgivor said:
> Having experience with Cotek, the sleep mode requires a load greater than 15W to wake it up, this wattage is generally greater than a cell phone charger uses, my suggestion is to use a automotive cigarette lighter USB charger directly to the battery for this purpose.
>
> An automatic on/off is something I've personally never heard of, just sleep or standby, it has to be alive to wake up, if it was dead it couldn't wake up, my theroy.
>
> One observation, you may be seriously underestimating the freezer / refrigerators energy needs, without data on it's requirements can't be 100% sure but from experience, would guess it's much more than 0.2-0.3 Kwh, this would mean your proposed system would be undersized.

I think this is the case. There is a remote on off feature, but not auto.

bill von novak · June 2017

pioneer said:

I need a 1000w inverter so I can handle the start up surge of the converted freezer. I have been looking at some of the most reviewed 1000w psw inverters such as the Sunforce 11240, Xantrex Prowatt sw1000, MicroSolar 1000w, Power Bright APS1000, and Renogy 1000w.

I have had good luck with the Prosine line - both the 1000 watt version and the 2.0 (2kW with charger.) They both have a search mode, and they both have an easily-relocatable control panel.

myocardia · June 2017

I never got the links edited in for the products I was referencing above, so here they come. This is a nice female lighter socket, that comes with both the wire and a 2.1A USB charger for $8. I have multiples of them, and they all work great.
https://www.amazon.com/VORCOOL-Cigarette-Lighter-Charger-Adapter/dp/B01B2K9MXM/ref=sr_1_1?ie=UTF8&qid=1496986954&sr=8-1&keywords=Vorcool+12V+120w

littleharbor2 · June 2017

Here's a couple other versions. I found on fleabay.

1000w pure sine wave inverter with automatic on/off ("standby" mode, "sleep" mode, etc)

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