Modified Sine Wave versus Pure Sine Wave

RetiredOne · 03-20-2020, 01:18 PM

My rig didn't come with an inverter, so I'm putting together the parts and pieces to put one in. Looking for opinions of Modified versus Pure for the inverter choice.

I know Pure is better for powering some sensitive items, with what I'm looking to power up, wondering if it matters. The items would be Flat screen TVs, coffee maker, laptop charger maybe cell phone charger. It wouldn't be the fridge or microwave. Maybe a future satellite system, don't have that yet...

We probably won't dry camp much, we usually go with hookups, so it won't get used that often.

The modified versions are less costly, not that it's a big factor. The modified versions are a bit smaller in size, that's a bigger issue based on the available space to locate it.

So, any thoughts?

Grumpy · 03-20-2020, 01:33 PM

The one JAYCO uses/used in the PINNACLE is a Modified Sine wave and I modified the wiring and ran our TV and Sat with no problem. It was the one installed for the resi fridge.

Pfflyer · 03-20-2020, 01:47 PM

Lot of articles on the web about this some are conflicting. From what I read (it was on the internet so it must be true) picture quality on flat screens would be affected and one article says most battery chargers wont work. If you want a cup of coffee I hope you have a bigger battery bank than what most campers and RV's I've seen come with.

GHen · 03-20-2020, 02:11 PM

This is an interesting question, I am also needing to upgrade my little 500w modified sine wave inverter. It runs everything just fine, it just is a little shy on power for the TV, stereo, satellite dish and sometimes a phone charger.

So, do I really need a pure sine wave also?

300w solar and total of 250amp hour batteries and we do boondock a lot.

Thomson · 03-20-2020, 02:22 PM

Read the Total Harmonic Distortion (THD) on the box you decide to purchase. If it's below 1.5% you should be good for electronics.

RetiredOne · 03-20-2020, 04:19 PM

Quote:

Originally Posted by Pfflyer

Lot of articles on the web about this some are conflicting. From what I read (it was on the internet so it must be true) picture quality on flat screens would be affected and one article says most battery chargers wont work. If you want a cup of coffee I hope you have a bigger battery bank than what most campers and RV's I've seen come with.

I have both types of inverters available, but I haven't tested the flat screens yet. I ran the coffeemaker off of the modified sine wave inverter, both to see what happens and to see how much it pulled from the batteries. There was a 1.2 volt drop during the drip cycle (700 watt machine), and when the cycle completed, the battery bank voltage only dropped 0.3 volts overall, and this is on older batteries. I have two Group 24 deep cycle batteries in my rig.

So, I don't think modified is a issue with the heating element of the coffeepot. Next test is the two flat screens...

RetiredOne · 03-20-2020, 04:22 PM

Quote:

Originally Posted by GHen

This is an interesting question, I am also needing to upgrade my little 500w modified sine wave inverter. It runs everything just fine, it just is a little shy on power for the TV, stereo, satellite dish and sometimes a phone charger.

I have 1200 watt units currently, but the big question is if the TV and satellite system will play nice with the modified sine wave unit? I would rather use that one because of size and the controls, only if it doesn't fry the electronics on specialty electronics.

Thomson · 03-20-2020, 04:34 PM

In general heating elements don't care about the quality of the sine wave. However, the electronics in the coffee maker might. Again, it is the trash from the inverter that determines the usefulness and that is measured by THD, which covers a lot of electrical bases that I won't discuss here.

Lake Huron · 03-20-2020, 05:06 PM

My Northpoint came with a Xantrex Freedom X 1000. It is a modified sinewave and all it was wired to power was the Residential fridge, which does have electronics. The reason I switched it out to the XC model is because I wanted one with a charging system to charge the batteries that the fridge draws power from when not plugged into shore power. The Xantrex tech I spoke with said a modified sinewave is ok for electronics but some electronics don't play well with modified. It was only a little more, so I got a true sinewave XC model. That 1000w inverter powers the fridge, even in defrost mode, pretty easily and can power a little more if I needed. It also influenced my decision to pay a little now instead of a lot later for just in case.

GHen · 03-20-2020, 06:02 PM

Been doing some more research and thought this was interesting but wondering is anyone can verify the accuracy.

On a modified sine wave for every 100watts of output it uses 153 watts of power.
On a pure sine wave for every 100 watts it uses 121 watts.

If so then a pure sine wave is a lot more efficient for the limited amp hour capacity of an rv.

EA37TS · 03-20-2020, 08:04 PM

Quote:

Originally Posted by Lake Huron

My Northpoint came with a Xantrex Freedom X 1000. It is a modified sinewave and all it was wired to power was the Residential fridge, which does have electronics. The reason I switched it out to the XC model is because I wanted one with a charging system to charge the batteries that the fridge draws power from when not plugged into shore power. The Xantrex tech I spoke with said a modified sinewave is ok for electronics but some electronics don't play well with modified. It was only a little more, so I got a true sinewave XC model. That 1000w inverter powers the fridge, even in defrost mode, pretty easily and can power a little more if I needed. It also influenced my decision to pay a little now instead of a lot later for just in case.

If your inverter is the Xantrex Freedom X it is True Sine and not Modified Sine. All Freedom X inverters are True Sine.

Nathan S. · 03-20-2020, 08:21 PM

I put a Xantrex 1800w modified in my trailer. Initially hooked it up to just the inside plugs and entertainment system. No problems. Then I decided I wanted it to power the GFCI circuit, mainly wanted the outside and basement plugs. Kept tripping the GFCI, had to change the GFCI to one Xantrex recommended which worked with the modified.

RetiredOne · 03-20-2020, 08:41 PM

Quote:

Originally Posted by GHen

On a modified sine wave for every 100watts of output it uses 153 watts of power.
On a pure sine wave for every 100 watts it uses 121 watts.

If so then a pure sine wave is a lot more efficient for the limited amp hour capacity of an rv.

That's interesting. Never heard of that before.

GHen · 03-20-2020, 09:04 PM

Quote:

Originally Posted by RetiredOne

That's interesting. Never heard of that before.

Well, one video showed the pure used less energy, another video showed no difference.

Both videos showed the pure sine wave used slightly more without a load. They have more electronics and any unit with a fan that run constantly also uses more. 1-2 amps was the average no load usage. Their advice was to always turn the inverter off when not in use. Seems logical.

Lake Huron · 03-20-2020, 09:25 PM

Quote:

Originally Posted by EA37TS

If your inverter is the Xantrex Freedom X it is True Sine and not Modified Sine. All Freedom X inverters are True Sine.

Thanks for your post and I apologize for posting some incorrect info. I knew my old inverter was a modified sinewave (MSW) and I thought it was a Freedom and it is not. I went to the basement and dug it out of the box and it is a Pro Series XM1000. That and the Xpower the Freedom HF and Freedom 458's are MSW. You are correct that the rest of the Freedom series, the PROwatt and PROsine are TSW inverters. My replacement is a Freedom XC.

RoyBraddy · 03-21-2020, 07:44 AM

We used to do alot of camping off grid so I wanted a POWER INVERTER with two 120VAC OUTLETS to plug in two multihead drop cords with one being on a cabinet top in both front and rear areas of my POPUP trailer.

I tried both PURE SINE WAVE and MODIFIED SINE WAVE Power Inverters and decided that since these were being used out for general purpose use I should go with the PURE SINE WAVE model to keep from burning up something that someone may plug into the multiple head drop cords. i.e. my portable 20-inch floor fan motor gets very hot if plugged into a Modified SINE WAVE Power Inverter. Also if I am using a heated lap blanket the going around joke is the lap blanket will short out when you start pulling the 120VAC lap blanket out of the bag. It seems to know what is going to happen haha..

We also always had extra lines and jitter when trying to watch TV using the modified version Power Inverter. Any sound making devices would have a background increased hum level.

These things I know are related to cheap POWER INVERTERS and the bigger ones seem to do quiet well interference wise and "Blue Smoke" periods..

I ended up with a very inexpensive 600WATT Pure SINE WAVE AIMS model Power Inverter...

google image

I have two 15-foot Multihead Extension Cords plugged into the two 120VAC outs on the AIMS Power Inverter. These are mounted on the back of a table top area where you can easily plug into it. These have ON-OFF switches on them as well.. I have these ALWAYS ON when camping off-grid...

google image

This is my floor plan layout showing where the two multihead drop cords are placed... My heavy 120VAC items like he Air Conditioner and Microwave were not used in my off-road setups... I use the stove top and fans and open windows at night...

Roy's image

Again this is what I come up with to do my OFF-ROAD camping... I'm sure others have their own ideas in what worked best for them...

Roy Ken

GHen · 03-21-2020, 08:38 AM

Roy, good info and nice job on your floor plan!

Jay Matt · 03-28-2020, 03:17 PM

Roy hit on the 'big' thing. Modified sine will not run ac induction motors well at all, inefficient at best, hazardous at worst. Ie, most fans. Electronics are more hit & miss, depending on the quality of the output. A pure sine will always work for all applications. Take the guesswork out and get a pure sine.

Florida Ranger · 03-28-2020, 06:02 PM

What type of inverter comes in a 2018 Greyhawk. I know it is 1000watt. Wondering if it is Pure or Modified.

waterwalkers · 03-29-2020, 02:16 AM

Quote:

Originally Posted by Jay Matt

Roy hit on the 'big' thing. Modified sine will not run ac induction motors well at all, inefficient at best, hazardous at worst. Ie, most fans. Electronics are more hit & miss, depending on the quality of the output. A pure sine will always work for all applications. Take the guesswork out and get a pure sine.

I'll second that, and add to it.

If you have to run medical equipment like an Oxygen Concentrator or CPAP machine, it's best to use the Pure Sine wave inverter. They cost way to much to risk using them on a Modified sine wave inverter.

Everything will work safely on a Pure Sine inverter. Why risk using the others?

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