Is there hope for reverse polarity damaged inverter?

[OKHerbie]

It finally happened!
After tinkering with mechanical and electrical stuff for over 40 years, I got careless and accidentally applied a half seconds worth of reverse polarity to a brand-new Sunforce 2500W sine wave inverter. All fuses are intact (8x40A, 1x20A), nothing looks charred, burned, deformed, bulging or smells funny, yet the inverter appears to be dead.
Has anybody been able to resurrect a wreck like this? Is it worth sending it away for repair? Should I sell the motorhome and buy a tent?

[Thurman]

After 38 years of Industrial Maintenance both mechanical and electrical on question comes to mind: I'm thinking that there may be an internal fuse within the units cabinet to prevent damage under this type circumstance. Might be worth a look inside. Good Luck

[OKHerbie]

Originally Posted by Thurman

After 38 years of Industrial Maintenance both mechanical and electrical on question comes to mind: I'm thinking that there may be an internal fuse within the units cabinet to prevent damage under this type circumstance. Might be worth a look inside. Good Luck

Thanks, that is exactly what I was hoping for. I found 9 fuses (8*40A and 1*20A), all of them ok.

[FleckDreher]

A) Fuses are intended to protect wires and cables from setting fires.

B) Semiconductors are much faster at "fusing" than any metal fuse.

C) Your inverter likely has a toasted semiconductor that can be repaired by someone who knows what they are doing.

D) Those people are becoming hard to find in our throw away world.

I would fix it.

[cavie]

You should have some form of battery inline fuse/disconnect within 6 feet of the battery. While you poking around check your 2 30/40 amp reverse polarity fuses on your converter.

[OKHerbie]

Originally Posted by FleckDreher

A) Fuses are intended to protect wires and cables from setting fires.

B) Semiconductors are much faster at "fusing" than any metal fuse.

C) Your inverter likely has a toasted semiconductor that can be repaired by someone who knows what they are doing.

D) Those people are becoming hard to find in our throw away world.

I would fix it.

Indeed, FleckDreher, fixing would be my first choice as these things are very expensive. I need to find somebody who can test transistors and diodes but, as you said, these people are hard to find.

[OKHerbie]

Originally Posted by cavie

You should have some form of battery inline fuse/disconnect within 6 feet of the battery. While you poking around check your 2 30/40 amp reverse polarity fuses on your converter.

I do have an in-line fuse in the battery cable in the RV. Goofy thing is, this happened on the work bench, just "checking" with booster cables. No fuse there, of course. I could kick myself in the head.

[TeachTexas]

Originally Posted by OKHerbie

I do have an in-line fuse in the battery cable in the RV. Goofy thing is, this happened on the work bench, just "checking" with booster cables. No fuse there, of course. I could kick myself in the head.

It may have a reverse polarity protection diode. It will probably not have any markings but should be on the negative lead in . It may also be on the positive side. It should be the first device in the circuit. Also look for possible in-trace fuses. These will be narrowed areas of the copper lines that are designed to open under extreme current situations. These types of protection are last line defense. Hope this helps.

[Flybob]

still may have a fuse as part of reverse polarity protection. Essentially a diode will short the incorrect incoming voltage long enough for the fuse to blow.

[cavie]

Originally Posted by OKHerbie

Thanks, that is exactly what I was hoping for. I found 9 fuses (8*40A and 1*20A), all of them ok.

Where did you find 8 40 amp fuses? you should be finding 5, 7, 10 and 15's. Did you find your converter?

[Bama Rambler]

Cavie, this is an INverter not a CONverter, As you know, those things have some quite large fusing.

OKHerbie -- Hopefully you can find a good schematic for it or someone that can repair it.

[TitanMike]

Check locally for an Electronic Instrument Repair shop.

A friend of mine owned one in Seattle and regularly repaired inverters from Seattle Fire Dept Aid/Paramedic vehicles. According to him the reverse polarity damage occured close to the power input and was a fairly easy repair.

FWIW, reverse polarity is almost assumed by designers and protection beyond just fuses is incorporated, often in the form of sacrificial, inexpensive, parts.

[OKHerbie]

Wow, lots of great, encouraging tips. Thank you all very much. I'll open up the box again tomorrow and look for additional possible points of trouble.
Thanks again.

[TGR]

Reverse polarity protection is usually provided by inline fuses and diodes. In the simplest form of protection, the diode is normally reverse biased and performs no function. However, when the connection’s polarity is reversed, the diodes will conduct and blow the fuses.

Carefully check each fuse for continuity because a visual inspection can be inaccurate. If that doesn’t find a bad fuse, look for an internal fuse or fuses inside the inverter case. If nothing is apparent, contact the manufacturer for their help.

[OKHerbie]

Originally Posted by TitanMike

FWIW, reverse polarity is almost assumed by designers and protection beyond just fuses is incorporated, often in the form of sacrificial, inexpensive, parts.

Are you saying I am not the only dunce who this happens to?
You're too kind, TitanMike

[aeblank]

Originally Posted by OKHerbie

Are you saying I am not the only dunce who this happens to?

You're too kind, TitanMike

Every (modern) automotive module has reverse polarity protection (and not fused, simply it can withstand it). Most certainly not the only one.

[AFDON]

Originally Posted by OKHerbie

Indeed, FleckDreher, fixing would be my first choice as these things are very expensive. I need to find somebody who can test transistors and diodes but, as you said, these people are hard to find.

Go to the FCC website, poke around for the locator page for HAM Operators, plug in your zip code. It will give a listing of all the HAM's in that zip. Call around, I'm betting you will find someone who is willing to help you.

Don, KI4ZQL

[cavie]

Originally Posted by Bama Rambler

Cavie, this is an INverter not a CONverter, As you know, those things have some quite large fusing.

OKHerbie -- Hopefully you can find a good schematic for it or someone that can repair it.

OK, I'm not the smartest knife in the drawer but something smaller then 40 amps has to be controlling the 12 volt circuitry in this RV. My pee brain tells me that is usually a converter. Help me out here.

[831 BHDS Flagstaff 2015]

Yes there is. My cousin did that to his camper. Blown both 40 anp fuses. Saved him. You should be ok

[Bama Rambler]

Originally Posted by cavie

OK, I'm not the smartest knife in the drawer but something smaller then 40 amps has to be controlling the 12 volt circuitry in this RV. My pee brain tells me that is usually a converter. Help me out here.

Keep in mind that an inverter normally has nothing to do with the normal 12 volt power that feeds the lights and 12 volt appliances in the RV. It just uses battery power to produce 120 VAC for some AC appliances, so it's going to have to have much larger fusing than the 12 volt power panel feeding the lights.

There are some inverter/chargers that recharge the batteries when plugged into shore power, but even those don't normally directly feed the 12 volt power panel, they're used to keep the batteries charged and the power panel gets it's feed from the batteries. (I'm sure that there are some inverter/chargers that can handle the 12 volt power directly without a battery, but let's discount those for this discussion.)