Will Reversed Polarities Kill An Inverter?

Thread Starter

Bill from Auss

Joined May 10, 2008
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


Joined Apr 20, 2004
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...
Last edited:


Joined Jul 22, 2007
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.


Joined Jun 20, 2007
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.

Thread Starter

Bill from Auss

Joined May 10, 2008
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% rating...my 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?