Modified sine wave vs pure sine wave inverters

verdigo · 01-30-13, 03:55 PM

I know pure sine is better but I am wondering how many $ better. For those of you running modified sine wave inverters are you having any problems and with what loads?
Thanks
Dennis

creeky · 01-30-13, 04:55 PM

I sold my modified sine wave and went to pure sine after toasting the rechargeable batteries on my Craftsman drill.

Yup. almost triple the cost, but worth every penny.

herlichka · 01-31-13, 11:50 AM

I've wondered about my flatscreen TV, I think you just answered my question!

verdigo · 02-02-13, 11:12 AM

Quote:

Originally Posted by creeky

I sold my modified sine wave and went to pure sine after toasting the rechargeable batteries on my Craftsman drill.

Yup. almost triple the cost, but worth every penny.

Thanks. Its good to have a made up mind one way or the other.

creeky · 02-10-13, 01:13 PM

hope your tv is okay. i tell you there were some tears when I recycled the dead batteries. it was cheaper to buy new ("sale": I got a set with circular saw and sawzall) and now I have a lovely $200 paper weight.
found the "modified sine wave" post online. went to the Sears site. Yup. they confirmed it. Cleaning my shop one day I found the manual... of course, no mention of the charging issue. c'est la vie.

Xringer · 02-13-13, 03:34 PM

Many of today's modern devices don't use a regular 60 Hz transformer.
Instead, they use a switching-type power supply. You can tell it's a switcher, if it's real light weight.

Most wall-wart models look like this.. http://www.nhpa40.org/b2b/pics/13W_S...er_Supply_.jpg

Here's a switcher design. Notice the AC input is immediately converted to DC.
http://www3.telus.net/chemelec/Proje...witching-1.png

This similar to power supplies used in modern PCs and LED displays etc.
(Even some Microwave ovens)!

Here's a modern TV power supply design.
Samsung Electro-Mechanics of Digital Technologies

Anyways, since these power supplies converted AC right into DC, I've tested a few,
and found they will also run off DC, no AC grid needed..

This type of PS will run just fine on MSW inverters.

I've also tested sump pumps, ACs, fans, a freezer, a Sony laptop PC, my new Lennovo PC and ASUS 22" LCD/LED monitor, and my A7 Airtap hotwater heater, using MSW.

~~~~

What doesn't work well, is very inductive loads, like large 60hz motors,
and small devices that have old style 60hz transformers built-in..
This type...

The small wallwarts will tend to buzz (louder than normal) and run warmer.

People who have used MSW on boats or in off-grid homes, have told me their old-tech microwave ovens would work, but had clock and timer problems.
Any built-in clock that uses the AC line's 60Hz as it's time base will have
a buzzy transformer and time errors. (Your inverter's 60Hz might be 58Hz)..

I would think twice before connecting any old CRT TV to MSW power. It might smoke them!

verdigo · 02-13-13, 09:37 PM

XRinger. So do you think a modern MSW inverter and newer appliances are a pretty safe bet?

Xringer · 02-13-13, 11:21 PM

If your charger says: "AC Adapter Power Supply 100-240VAC to 5VDC"
That's a good clue there is no 60hz power transformer inside.
(Unless there's a switch labeled 120/220)..

There could be transformer buzzing and heating with the old type PS..
http://3.bp.blogspot.com/-mWAI4eA-14...00/power30.gif

Newer PS, no big deal if you use MSW..
http://www.electroniq.net/files/surs...wer-supply.jpg
This one can be driven by DC voltage, directly from batteries or solar panels..

I have a new Dehumidifier (from Home Depot) it worked on MSW,
but it made so much noise, I gave up on it pretty quick.
Even on regular grid power, it sounds like an air boat..(noisy).

There is info on the web..
Inverter FAQ - DonRowe.com - Frequently Asked Questions about Power Inverters

creeky · 02-15-13, 02:32 PM

I have seen posts that suggest any DC load over 12v will not be happy with MSW.
I have to charge 18v power tools, my laptop is 19v. If you're going offgrid, why risk expensive equipment?
Verdigo, not sure what size inverter you're looking at, but a 1000w sunforce pure sine is less than 200 (179) on Amazon right now.

Xringer · 02-15-13, 03:21 PM

Quote:

Originally Posted by creeky

I have seen posts that suggest any DC load over 12v will not be happy with MSW.
I have to charge 18v power tools, my laptop is 19v. If you're going offgrid, why risk expensive equipment?
Verdigo, not sure what size inverter you're looking at, but a 1000w sunforce pure sine is less than 200 (179) on Amazon right now.

A DC 'load' is resistance, measured in Ohms, not volts.
All loads are resistive(R) at DC voltages.

Your laptop might run on 19VDC, but you are never going to plug 120vac into the 19VDC socket on the laptop..
What determines compatibility is the type of charger you own..
If it's a big heavy transformer charger/power supply, it could have a problem.
But, if it was manufactured in this century, it's likely a switching power supply.

Switching power supplies (see above post), don't care what kind of voltage
you feed them, so long as you don't try to use 230vac on a 120vac charger..
Today, many small chargers(and appliances) will take 100 to 240 vac..
I've used those chargers on 122 volts DC (from solar panels) and some
small 1Amp wallwarts will even run okay on 50+ DC (from my 48v battery bank).

01-30-13, 03:55 PM	#1
verdigo Helper EcoRenovator Join Date: Dec 2012 Location: Cave City Kentucky Posts: 45 Thanks: 7 Thanked 7 Times in 4 Posts	Modified sine wave vs pure sine wave inverters I know pure sine is better but I am wondering how many $ better. For those of you running modified sine wave inverters are you having any problems and with what loads? Thanks Dennis

02-13-13, 03:34 PM	#6
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Depends on the loads. Many of today's modern devices don't use a regular 60 Hz transformer. Instead, they use a switching-type power supply. You can tell it's a switcher, if it's real light weight. Most wall-wart models look like this.. http://www.nhpa40.org/b2b/pics/13W_S...er_Supply_.jpg Here's a switcher design. Notice the AC input is immediately converted to DC. http://www3.telus.net/chemelec/Proje...witching-1.png This similar to power supplies used in modern PCs and LED displays etc. (Even some Microwave ovens)! Here's a modern TV power supply design. Samsung Electro-Mechanics of Digital Technologies Anyways, since these power supplies converted AC right into DC, I've tested a few, and found they will also run off DC, no AC grid needed.. This type of PS will run just fine on MSW inverters. I've also tested sump pumps, ACs, fans, a freezer, a Sony laptop PC, my new Lennovo PC and ASUS 22" LCD/LED monitor, and my A7 Airtap hotwater heater, using MSW. ~~~~ What doesn't work well, is very inductive loads, like large 60hz motors, and small devices that have old style 60hz transformers built-in.. This type... The small wallwarts will tend to buzz (louder than normal) and run warmer. People who have used MSW on boats or in off-grid homes, have told me their old-tech microwave ovens would work, but had clock and timer problems. Any built-in clock that uses the AC line's 60Hz as it's time base will have a buzzy transformer and time errors. (Your inverter's 60Hz might be 58Hz).. I would think twice before connecting any old CRT TV to MSW power. It might smoke them! __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 02-13-13 at 03:36 PM..

02-13-13, 11:21 PM	#8
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Depends on the device.. You phone charger should be fine.. If your charger says: "AC Adapter Power Supply 100-240VAC to 5VDC" That's a good clue there is no 60hz power transformer inside. (Unless there's a switch labeled 120/220).. There could be transformer buzzing and heating with the old type PS.. http://3.bp.blogspot.com/-mWAI4eA-14...00/power30.gif Newer PS, no big deal if you use MSW.. http://www.electroniq.net/files/surs...wer-supply.jpg This one can be driven by DC voltage, directly from batteries or solar panels.. I have a new Dehumidifier (from Home Depot) it worked on MSW, but it made so much noise, I gave up on it pretty quick. Even on regular grid power, it sounds like an air boat..(noisy). There is info on the web.. Inverter FAQ - DonRowe.com - Frequently Asked Questions about Power Inverters __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

01-30-13, 04:55 PM	#2
creeky Journeyman EcoRenovator Join Date: Jun 2011 Location: a field somewhere Posts: 304 Thanks: 64 Thanked 44 Times in 31 Posts	I sold my modified sine wave and went to pure sine after toasting the rechargeable batteries on my Craftsman drill. Yup. almost triple the cost, but worth every penny.

01-31-13, 11:50 AM	#3
herlichka Apprentice EcoRenovator Join Date: Oct 2010 Location: Simcoe County, Ontario, Canada Posts: 102 Thanks: 11 Thanked 15 Times in 10 Posts	I've wondered about my flatscreen TV, I think you just answered my question!

02-10-13, 01:13 PM	#5
creeky Journeyman EcoRenovator Join Date: Jun 2011 Location: a field somewhere Posts: 304 Thanks: 64 Thanked 44 Times in 31 Posts	hope your tv is okay. i tell you there were some tears when I recycled the dead batteries. it was cheaper to buy new ("sale": I got a set with circular saw and sawzall) and now I have a lovely $200 paper weight. found the "modified sine wave" post online. went to the Sears site. Yup. they confirmed it. Cleaning my shop one day I found the manual... of course, no mention of the charging issue. c'est la vie.

02-13-13, 09:37 PM	#7
verdigo Helper EcoRenovator Join Date: Dec 2012 Location: Cave City Kentucky Posts: 45 Thanks: 7 Thanked 7 Times in 4 Posts	XRinger. So do you think a modern MSW inverter and newer appliances are a pretty safe bet?

02-15-13, 02:32 PM	#9
creeky Journeyman EcoRenovator Join Date: Jun 2011 Location: a field somewhere Posts: 304 Thanks: 64 Thanked 44 Times in 31 Posts	I have seen posts that suggest any DC load over 12v will not be happy with MSW. I have to charge 18v power tools, my laptop is 19v. If you're going offgrid, why risk expensive equipment? Verdigo, not sure what size inverter you're looking at, but a 1000w sunforce pure sine is less than 200 (179) on Amazon right now.