Author Topic: Chinese inverters on ebay  (Read 9279 times)

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Offline jack11

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Chinese inverters on ebay
« on: April 30, 2013, 07:02:04 PM »
there is a whole bunch of chinese inverters listed on ebay, the ones displayed by the playboy bunnies.

see for example: http://www.ebay.com/itm/220990186480?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

500 to 8000W power levels, 12 and 24 Vdc, 110 and 220 Vac, pure sine wave output, and cheap, some about $0.08/W.

the name of the outfit that makes them is not listed.

I got a hold of the user's manual, they are extremely detailed in explaining how to repair the mosfets, diodes, resistors, etc in their troubleshooting guide (perhaps because they break all the time).

I don't want to be the fist sucker to fall for what possibly may be a piece of junk. On the other hand, this may be a product comparable in quality to say Harbor Freight inverters that I have had some luck with (also from China).

Has anyone bought any of these before, and if so then can you provide feedback?

Offline Wolvenar

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Re: Chinese inverters on ebay
« Reply #1 on: May 01, 2013, 12:59:46 AM »
Well, even one of the big name inverters are made in China now. (Xantrax) or that is Schneider Electric as its now named.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline oztules

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Re: Chinese inverters on ebay
« Reply #2 on: May 01, 2013, 03:13:18 AM »
I have heard mixed reviews of the power jack inverters. I have had some experience with their grid tie inverters which I purchased just to see how they worked.

It was not long into testing that I noticed the capacitors starting to "leak"... which surprised me some. Obviously the ripple killed them quickly. I don't know how that equates to their normal inverters.

Chinese stuff ranges from the excellent to the poor, and price is not the only indicator. I bought a 6000w 18000watt surge inverter as can be seen here: http://www.anotherpower.com/board/index.php/topic,780.msg7498.html#msg7498

As explained, it is very hungry on idle without modification, but apart from that is a very sturdy device for off grid applications.

For the money, the power jack style does not seem  like  a kings ransom to find out, but gee.... I would look at the filter caps early on in it's service to see how they fare.

People seem to be unaware of just how damaging ripple is to caps. A few years from now there will be a lot of grid tie inverters being fixed or tossed because of just this.... and most other newer devices like LCD LED and plasma tv's. .........Starting to see a few now even here. In nearly every case, the caps start to fail, and take the pwm chips with them....... mostly chips I have never heard of before too....

I would not know what to recommend in this space, but it will have something to do with how your using it....permanent or spasmodic.

I trust the "heavy low frequency inverters" far more than the HF inverters...... plus you get galvanic isolation of the output from the input via a meaty transformer, and the circuitry seems easier to follow and the switching is done before the transformer.... gives a bit of "give" in wicked conditions.

The HF switching ones do the H bridge switching after the isolation, and seem a bit more prone to fizzle with different loads without good reason.... they are exposed directly to the load.

One rule to note: Try your best to keep the unit cool. Caps last much much much longer at cooler temps. They are the weak link, assuming the circuit is sound to start with.


.................oztules

Edit. PS:  I have it on fairly good authority... that I would not be allowed to keep the bunnies.... she said so :'( :'(
Flinders Island...... Australia

Offline Wolvenar

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Re: Chinese inverters on ebay
« Reply #3 on: May 01, 2013, 04:25:14 AM »
I am not sure how it relates to inverter applications, but besides the heavy ripple,
China seems to be still making or at least shipping devices with extremely inferior caps.

The problem that started in the 90s has not been fixed.
I have seen more just plain bad caps out there than I care to keep track of, most are just by age break down without the device ever seeing use.
At the same rate I have a few devices that are only months old with capacitor troubles already in a circuit that shouldn't.

Premature leaky caps can be bad caps, poorly designed circuits, or just hostile environments, so it's always a case by case of course.

More info here http://en.wikipedia.org/wiki/Capacitor_plague


Side note:
For anyone interested,  the Dish VIP922 is one device that widely and invariably suffers this fate.
If you own and want to keep this model of receiver, your only working solution is to replace all the electrolytic caps in it yourself.
Otherwise Dish will replace it with "The Hopper"

I should do a post on how to repair and tweak this receiver someday.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline oztules

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Re: Chinese inverters on ebay
« Reply #4 on: May 01, 2013, 04:52:37 AM »
Very interesting article... and powerjack is from Taiwan  (Republic of China).......Maybe buy the unit and replace the caps early on, then maybe a good deal... who knows with these things.
Thanks for the read.



................oztules
Flinders Island...... Australia

Offline jack11

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Re: Chinese inverters on ebay
« Reply #5 on: May 01, 2013, 02:22:09 PM »
ok, so we now know it's the Power Jack brand.

I found some info on the internet, mostly unfavorable.

the efficiency is low 87%, but at least they don't lie about it.

the caps seem to blow up frequently, but that's a problem in general (I've lost a motherboard and a PC power supply due to ruptured caps, in the time frame they had the "capacitor plague").

However, the Power Jack inverters CAN be repaired, as the following youtube video demonstrates (must see):

http://www.youtube.com/watch?v=P1TzSPCvxhI

my conclusion is: JUNK (product quality and customer service), I'll stay away from them.

Offline oztules

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Re: Chinese inverters on ebay
« Reply #6 on: May 01, 2013, 03:49:14 PM »
Not sure if I would use that clip as a reference to how good it may/not be. From memory, the boards are computer robot constructed, so they should be fine quality wise, the assembly is fixable, and the caps replaceable.... depends what you want to use it for, how much you like fiddling, how much you want to spend to trade these things off.

Like I said, I like the 50kg (>100lbs) inverters, but they are terribly expensive except for the brand (generic) I bought. Probably no change out of 4000 bucks... so I was prepared to do some work for a 3000 dollar saving. It is a very useful tool now. ( commercial toroids that size can be had from UK and Aust for 700-1000 dollars. From America also, but did not price them there. The transformers weigh about 20kgs... so overseas freight is expensive. (44 lbs).

For intermittent use, maybe the power-jack style would be ok.... depends on your abilities, and threshold of pain with shelling out thousands for something really only worth barely more than what the Chinese are charging.  Expensive ones are not that different, but for the service and backup (supposedly), which is useless over here.... there is no backup. The components are pretty much the same... better caps, .... and what else can they have better?

The silicon remains essentially the same. There are not 5 times better or more components in the expensive ones, and they need service and backup too..... they fail as well apparently.

Like I said, I don't know what to submit as a "buy", but your eyes are open now.



.................oztules
Flinders Island...... Australia

Offline jack11

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Re: Chinese inverters on ebay
« Reply #7 on: May 02, 2013, 03:25:32 PM »
I do allow for some honest equipment failures, and I am not afraid to tinker with things to repair or improve, but I also expect due diligence for the manufacturer in constructing/supporting their products.
The multiple videos and written feedback from several unconnected people I've seen show the Power Jack to be EXTREMELY sloppy construction, and no real help from the maker in correcting/replacing the inverters, all bordering on total neglect.
I've not seen as bad inverter reviews as the Power Jack ones.

The one thing I have not seen is any info about their pure sine wave topology they use (full-bridge, NPC, HF transformer, transformerless, how they generate PWM controls, etc).
By knowing the topology they chose for the switching and control functions I could make a judgment on how they compare against the other brands Samlex, GoPower, etc, at least concerning their design choices.
Also, if I don't know the topology then I don't know how easy/difficult it would be for me to get inside of their failed inverter and make it work again, either by fixing the whole thing or re-using a part of it with my own fix.

I guess, based on what I've seen - and I maybe I haven't looked at all the right info, these inverters have exceeded my threshold of what I'd consider junk.

Offline striider

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Re: Chinese inverters on ebay
« Reply #8 on: February 12, 2014, 02:32:38 AM »
I have not used a Power jack inverter, but I have experienced issues with the "bad caps" in my high quality 3 year old Samsung LCD TV.  The power would come on, and it would start cycling on and off.  Google, a 12 dollar cap kit off Ebay and an hour of my time saved me $1000 on a new TV. 

So I can see how your tolerance for repair work can directly impact your tolerance for a (hopefully only) slightly inferior product at a large enough cost savings.  Good point Oztules.

Offline oztules

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Re: Chinese inverters on ebay
« Reply #9 on: February 13, 2014, 07:33:59 PM »
Flinders Island...... Australia