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Old 05-11-2008, 02:34 AM
Bill from Auss Bill from Auss is offline
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Post Will Reversed Polarities Kill An Inverter?

G'day mates,

I'm new to this forum, I'm also new to working with inverters.
I bought a 300W inverter off eBay and when it arrived I checked the box and found everything as promised on the sales page. My 12yo grandson who was visiting us asked what I had bought and what was I going to use it for, I told him and he wanted to try it out, I then got tied up on the phone and my grandson went to my shed with the inverter and a 240v tablelamp, he returned to tell me the inverter was not working and when I checked I seen he had reversed the polarieties on the battery...I removed the terminal clamps and placed them back the right way around but the lamp would not light.
The battery was/is fully charged.
The light globe is working as the light is now working in my living room.
Neither the power light or the fault light on the inverter come on when the inverter is attached to a fully chatged battery.
Has my grandson destroyed my inverter by conecting it wrongly to the battery?
I have no wish to tell the suppliers they sent me a faulty inverter and seek a replacement if it's my fault the inverter was dameaged...i.e. I permitted my grandson to make the connection to the battery.

Thanking you for your advice,

Bill from Auss
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Old 05-11-2008, 02:50 AM
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beenthere beenthere is offline
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That depends quite a bit on the internal circuit. If there are diodes in the battery supply path, then no harm would have been done. If not, then all the drive circuitry might have been converted to junk.

Take a close look at the printed circuit board. See if any resistors look charred. See if any capacitors look like they have blown their vents or got taller than the label sleeve. See if any discreet transistors have cracks in the epoxy (same for integrated circuits). Quite often, applying reverse voltage to a circuit will cause visible damage - and then ther is always that horrible smell of cooked phenolic...
First comes the hardware, then the software.

Last edited by beenthere; 05-11-2008 at 02:54 AM. Reason: addition
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Old 05-11-2008, 03:05 AM
HarveyH42 HarveyH42 is offline
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Maybe a fuse... Would be a very bad design, clip on leads, and no reverse polarity protection. Can you post a brand/model number? Maybe a search on the web will turn something up, least give a better idea what you are working with.
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Old 05-11-2008, 03:20 AM
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S_lannan S_lannan is offline
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I'm 99% sure that any inverter from jaycar will not survive reverse polarity. That includes the whole range.

I've never seen an inverter that can survive reverse polarity. Sure they have fuses, but fuses are not fast enough in a lot of cases.

I've seen some amps with 20A-40A fuses and inside them they had fets literally blown to pieces.
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Old 05-11-2008, 10:47 PM
Audioguru Audioguru is offline
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Many people sell defective junk on E-Bay. Maybe you should.
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Old 06-18-2008, 11:33 AM
Bill from Auss Bill from Auss is offline
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Post Thanks but No Thanks!

Originally Posted by Audioguru View Post
Many people sell defective junk on E-Bay. Maybe you should.
G'day mates and thanks for the answers, as for the quote above...That's not me! I don't need a dollar that badly...been selling on eBay since it first started and still have a 100% word is my bond!

Anyway, I pulled the unit apart, replaced the fuse and it's working fine now but once again, thanks for your views.


PS. Anyone know anything about converting a petro car to an electric car?
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Old 06-18-2008, 02:14 PM
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thingmaker3 thingmaker3 is offline
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In the interests of good housekeeping, I've pushed the conversion discussion into a new thread:
"I want to establish in your mind very clearly that you must not think I deny all that I do not admit. On the contrary, I think there are many things which may be true, and which I shall receive as such hereafter, though I do not as yet receive them; but that is not because there is any proof to the contrary, but that the proof in the affirmative is not yet sufficient for me"
- Michael Faraday
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