Battery voltage spike with Trace inverter

[Rabrsniver]

I have had my system for 4 years. It is made up of a Trace SW4024 inverter, 12 Trojan L-16 HC batteries (wired as 24 volts) and a propane generator. It has run great since I installed it.

The other night I turned on the bath exhaust fan and the whole house went dark. The inverter room had that bad electrical burning smell and the readout showed OVERCURENT and HEATSINK OVERTEMP errors. I don't think the OVERCURRENT really happened because there were no unusual loads on. The manual said that the HEATSINK OVERTEMP was an automatically resettable error. The cooling fan ran and ran and never shut off. The inverter never reset.

I took the inverter off the wall and found some components on the heatsink near the battery connections black. Obviously the inverter needs repair. I just want to pinpoint the problem before I reinstall it.

I have a Trimetric meter and the battery high voltage showed 48.7 volts. What would cause a 24 volt system to put out 48 volts? I'm assuming this is what fried the inverter. I just want to correct this problem before I fry my repaired inverter. I checked all the battery connections and they were tight. Some weren't totally "cranked" so I tightened them. Other than that, nothing seems visually wrong. Any comments or suggestions would be appreciated.

Thanks,

John

[wpowokal]

My guess, part of the MOSFET driver circuit failed causing the MOSFET's to remain conducting when they should switch. Causing hot heatsink and magic smoke escaping, them little thingies mounted to the heat sink are the MOSFET's.

This would account for the overcurrent, volt peak would be a result of the ensuing chaos.

All up probally a faily common inverter failure, but I'm sure others can shed more light on this.

allan down under

[Nando]

It seems that the :

1. the battery opened up allowing the generator to increase its voltage.
   
2. The generator produced a much higher voltage than the 24 volts ( Bulk voltage) up to what you read.
   
3. the generator regulator may have gone bad generating high voltage ( as you read it).
   
   

The regulator system does not have a protector to stop producing the high voltage and it may be that failed in short circuit (internal regulator) forcing high voltage.

What type of information you have for the gas generator ?.

----------specially the regulator-----------

I have used protection circuits for that purpose and it is a Fuse and a SCR circuit that is triggered by a higher voltage than the defined as a maximum, opening the line from the battery to the protected circuit.

As well, another circuit protecting the batteries if such is needed.

The protecting circuits when fired may have an indicator, in my case, done many years ago it would trigger a small flip-flop mechanical indicator.

Regards and hope it helps.

Nando

[Rabrsniver]

Hi Nando,

Thanks for the info. My generator is an Onan 6.5NHD running on propane. Its funny that you should mention the voltage regulator. Recently, the generator would shut down after 45 minutes every time it tried to run. I finally traced it down to a bad voltage regulator. Some component was getting too hot at about 45 minutes and then the voltage would drop off to almost zero and the inverter would fall out of sync and shut things down. I found that if  I put the regulator in a ziplock bag and then dunked it into a bowl of water that the generator would run and run and....

So I ordered a new voltage regulator (Onan parts are ridiculously priced) and that solved the problem. (I hope)!

So for the last week or so, we have been running strictly off the generator and (knock wood) it has been doing fine.

I'm a little confused though. How could the generator's 120 volt output make the batteries produce 48 volts? Unless the charger in the Trace freaked out. But if the batteries were charged to 48 volts, wouldn't they explode or at least fail? I get the impression that it was a momentary thing somehow, just enough to fry the inverter.

I'll be honest - electricity isn't my strong point. I'm a general contractor and have no trouble building things I can "see." But when it comes to energy flying through wires and such, I guess I have a mental block. I can wire a house, but when you throw in relays, transformers and such, well...

John

[Rabrsniver]

Hi Alan,

Well that sounds kind of encouraging. At least it sounds less expensive. If the MOSFETs are the culprit and they are mounted on top of the heatsink, then hopefully the cicuit board survived. I have to go about 200 miles for repair, after getting to the mainland from the island we are on. Meantime we're racking up the hours on the generator.

So is there any special reason for the MOSFET failure or was I just "lucky?" I guess after 4 years it was just my time and I shouldn't complain.

John

[wpowokal]

John,

    Nando's comments relate to a situation where the batteries are disconnected and you have an uncontrolled voltage source ie wind generator, but inverter still connected to this uncontrolled source.

For your propane generator with regulator you should be OK.

The peak voltage reading would have been generated by the failiure of the inverter, it did occure but briefly.

Your batterys would keep the volts much lower, most likeley even if exposed to a 48v source, they may boil like crazy but. Big subject this.

Confirming the regulators correct operation is easy, look at volts/amps while charging and the volts when regulating, I suspect you already know this.

I think the inverter failure, although after only 4 years fits into the catogory of $#|+ happens.

allan down under  

[Rabrsniver]

Allan,

Thanks for the info. You're right, SH*T does happen! This summer has been a bad one. If you want, check my other post about charging my 24 volt batteries with my 48 volt array.

Maybe everyting is related somehow.

John

[Nando]

Hey do not throw that regulator !!

If you want send it to me, I may be able to repair it if it is not casted in RESIN

Let me know nando37-at-comcast-dot-net

Regards

Nando