Pure sine wave inverter Vs modified wave

Submitted: Tuesday, Jul 16, 2002 at 00:00
ThreadID: 1500 Views:8156 Replies:5 FollowUps:4
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I know that pure sine wave inverters are superior, more efficient, and more suitable to more sensitive electronic equipment. But those flogged mostly seem to be modified square wave inverters - so what is the practical story - has anyone's fridge, phone recharger or laptop stopped or blown up on a modified square wave inverter ?
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Reply By: rodeoowner - Tuesday, Jul 16, 2002 at 00:00

Tuesday, Jul 16, 2002 at 00:00
Paul, I had a D.Smith modified square wave inverter and it used to run by battery drill recharger, video camera battery charger and 34cm colour TV ok. The only thing that it wouldn't run was my electric shaver, although it did run my electric hair clippers! Cheers.
AnswerID: 4905

Reply By: Mark - Wednesday, Jul 17, 2002 at 00:00

Wednesday, Jul 17, 2002 at 00:00

Modified sine wave inverters produce more harmonics than pure sinewave inverters, this is why they are not suitable for harmonic sensitive equipment such as laptop computers. Other devices such as battery chargers that use capacitors in the circuit can also be damaged by cheaper modified sine wave inverters. Fridge compressors don't like modified sinewaves either and on startup the initial surge can also damage an under rated inverter.

AnswerID: 4918

Reply By: ExplorOz Team - David - Wednesday, Jul 17, 2002 at 00:00

Wednesday, Jul 17, 2002 at 00:00
Paul,We run laptops (always on power whenever the vehicle is running), video battery chargers, Sat phone chargers, Coleman rechargable lights, 240V light bulbs, sleander blenders and a just about anything else you can imagine on our DSE 300Watt cheap inverter. I am an electronics engineer and we could argue the toss about modified wave vs pure wave systems all night however, I have never had any problems with the modified wave equipment. Additionally, I am in the IT business supporting large computer network systems with a mix of UPS systems with modified and pure wave equipment and I can not really in todays market find much that will not run with the modified inverter systems. If your equipment uses a transformer based DC output then you really will not have any problems, some AC supplied system may need to be looked at bit closer but really lets be practical power supply systems today are far superior and will handle a lot more poor input power than in years gone by.I would be interested to hear from anyone that has had a problem with modified wave inverters as I would think the occurance's would be far between. Just make sure you do not overload the system. As for shavers I do not use electric shavers but if it has a battery in it ie. rechargable you would not have a problem.All the best David
AnswerID: 4922

Follow Up By: Paul - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
David i am totally fascinated, can we argue all night please - who's next ?
FollowupID: 2108

Reply By: Member - Sam - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Thanks David. That has just cleared up a heap of issues for me in one hit. Especially seeing as I need to aquire an inverter post haste for a trip I am heading off on in about a months time. From what you have said, the 300W DSE unit will be perfect for my requirements. Many thanks. cheers, Sam.
AnswerID: 4930

Follow Up By: Rodeoowner - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Hey Sam. Sounds like David is happy with his DSE inverter. I have also seen the same unit with different brand stickers on it. My experience with this unit is not a good one. After about 9 months of very light use (video cameray and drill battery recharging) myn 300w unit bit the dust. When turning it on it would beep and the red light would come on as if it was working, but then would shut down after maybe 2 seconds. As it was still under warranty I returned it and it was repaired. Apparently some of the electronic components on the PCB had blown. About 4 months later it died again, same problem. It was now under warranty, but I took it back to DSE, but was told their minimum service fee was $95. And that wasn't even to replace any parts. As I only paid $150 for it in the first place and there was no guarantee that it wouldn't break down again, I decided not to go ahead. I really need (want?!) an inverter, but will save my pennies and purchase a better quality unit next time. DSE must sell thousands of these, so you would think they would be ultra reliable. I am not suggesting that they are a poor quality product, maybe I just got a lemon? Cheers.
FollowupID: 2113

Reply By: Member - Sam - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
David, in addition to my last post. How have you connected the unit up to the vehicle's power supply. Do you use the cigarette lighter plug (if it comes with one - the DSE site doesn't mention/picture it), and if so, do you find it over heating? or have you modified it to use a heavier duty 12v connection? cheers, Sam.
AnswerID: 4931

Follow Up By: Exploroz Team - David - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Sam,I wired the unit into the car using very heavy gauge wire (not exactly sure of gauge at the moment). I also wanted to be able to switch it on/off from the dash and also the rear of the car. Mine is mounted on the cargo barrier and I have put a double adaptor into it with fixed (installed) leads running to the back and the front (under the passenger seat). My switching setup was made with a large 40-50Amp relay installed about a few inches away from the inverter using the same heavy wiring and soldered connections. I then basically switch the relay with some very light wire from the dash and rear of the car with the switching system in parallel (this means either switch will operate the inverter). I do this as we tend to plug and unplug devices on the fly and I want to switch the gear off when Michelle is doing the unplugging. This is important due to electrical grounding issues. The vehicle is not grounded due to the tyres. This may cause you to get a low current buzz from certain equipment whilst it is running off the inverter (will not kill you but you may feel it). Hence, I like to turn the inverter off when we plug/unplug devices.All the best David
FollowupID: 2109

Follow Up By: Member - Sam - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Thanks David. Will probly look into a similar setup. Just gotta find room for it. The Hilux is quickly running out of spaces to put all these things. cheers, Sam.
FollowupID: 2110

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