Blowing up inverters!

[Otto_Pylotte]

Hi there, I could use some input before I blow up another inverter.

I have tried a number of configurations where I copy the hybrid on/off grid setup that Will did in one of his videos.

I have a 24v 280A LiFePO4 battery connected to a pair of parallel Renogy 100A/24V charge controllers and a hybrid all-in one 3000W/24V inverter and a 150A breaker.

Despite trying different standalone ATS's and different inverters/charge controllers I repeatedly have the same issue. I get the same issue despite entirely different hardware and configurations.

The battery input power mosfets on the inverter short and fail. On latest hybrid inverter the capacitors also blow up and have even caught fire.
This seems to happen no matter what inverter, charge controller or battery is being used. It can sometimes take a couple of days or weeks for the failure to occur. Im not always there to see the failure so it's hard to troubleshoot what is happening at that exact moment. The hybrid inverter continues to work but with the shorted battery input that functions is dead. It does however switch to grid and keep going, so it looks like just that battery input section of the pcb is getting fried.

After many failures the only pattern I can see is it appears to happen during the day in full sun (ie: charge controllers charging) and when my battery is charged to 100%.

My current (unproven) theory is that once the battery is fully charged it is shutting down with an overcharge fault and sending a surge of dc voltage from the charge controllers directly to the inverter which after a couple of weeks of doing this causes the mosfets/capacitors to fail and short.

My only other guess is the daily switching from grid to battery each day gradually damages the mosfets with an initial surge until they fail after a few days. If this was the case though I would think every ATS based install would have this same problem

I think by ensuring the charge controllers are set not to exceed a max voltage less than the battery's max voltage will fix this issue ... but I may be on the wrong track entirely and wanted to put it out there before I blow up any more inverters (it's getting expensive).

Any insight on what I might be doing wrong would be greatly appreciated.

Otto

 

[Bud Martin]

1) Make and model of this 'hybrid all-in one 3000W/24V inverter '?
2) Wiring diagram of the setup?

 

[SpongeboB Sinewave]

Data logging the battery voltage and PV input voltage might be something to try. Just an suggestion.

Maybe one of these inexpensive (~ $80) 4-channel Dataq data loggers running at around 20 captures per second might do the trick.

This would require some kind of computer like a laptop using their software I think.

DI-1100 4-channel USB Data Acquisition Starter Kit

DI-1100 USB Data Acquisition starter kit with Windaq software. Measures ±10V.

www.dataq.com

Looks like dataq forgot to renew their web certificate but it should still be safe. I didn't have an issue when I used Firefox.
OR just search for that product if you are interested and see another WWW site.

Then you could finally correlate the blowup with an event to verify and also watch to see if there is any funny business happening with the battery voltage as a result of your theory about the charge controller. You might also monitor one of the AC lines to see if the AC output stops as well.
20 samples per second will not show you the AC sinewave because of aliasing but should still tell you when the AC stops.
The DI-1100 is capable of capturing at 20 kHz but I think that might be a bit overboard. 20 S/sec should be fast enough to capture what you want without filling up your disk drive.

The DI-1100 has differential inputs with high value resistors so it should handle your voltage. Just check to be sure.

boB

 

[MisterSandals]

24v 280A LiFePO4 battery connected to a pair of parallel Renogy 100A/24V charge controllers and a hybrid all-in one 3000W/24V inverter

What amp rate are you charging at?
What is your max charge voltage from your SCC's?
Is your hybrid also charging your battery?

Happen to have a pic or diagram of your setup (as previously requested)?

 

[RCinFLA]

Need more info on type of inverter and actual hookup, but likely related to your use of ATS.

Hybrid inverters synchronize to AC input and don't take well to having an ATS immediately flipping to alternate AC source with a different random phase relationship to first AC source.

Obviously, a potential disaster for switching inverter AC input source, but also possible to do damage to output of inverter due to an ATS on output side with a motor load kick-back when its AC source phase is suddenly shifted. Like from an ATS output changing from grid source to inverter AC output.

A real ATS transfer switch drops AC output for some period of time to allow loads to drop and start up again from a new phase source.

Cheap ATS's with a simple DPDT relay that immediately flip from one AC source to another should be avoided. They will work okay if you don't have any reactive loads. Some power factor correcting power supplies, like many newer computer power supplies, can be damaged by a sudden AC input phase shift. Computer backup power units pre-synchronize their AC inverters to AC input source before allowing a switch over to battery backup power and when AC grid returns, they slowly adjust their inverter phase to match grid before jumping back on grid.

 

[Otto_Pylotte]

What amp rate are you charging at?
What is your max charge voltage from your SCC's?
Is your hybrid also charging your battery?

Happen to have a pic or diagram of your setup (as previously requested)?

Here is a sample diagram. As I mentioned though the type of hardware doesn’t seem to matter. It damages the inverter dc input on several different hardware models

 

[Otto_Pylotte]

1) Make and model of this 'hybrid all-in one 3000W/24V inverter '?
2) Wiring diagram of the setup?

It’s a powmr 3k hybrid and renogy 100a cc

 

[Otto_Pylotte]

What amp rate are you charging at?
What is your max charge voltage from your SCC's?
Is your hybrid also charging your battery?

Happen to have a pic or diagram of your setup (as previously requested)?

Here it is

 

[Skypower]

If your solar charge control is set way to high and/or the batteries are disconnecting (high cell ( imbalance) or high battery voltage) you could be sending power directly to the inverter without a battery to smooth out ripple. Your batteries could reset and if there’s no Bluetooth app, you’d never know if it alarmed (no record). I agree with others. A data logger would help.

 

[400bird]

Yeah, with the info provided thus far, my only opinion is it likely has to do with component quality over system design.

A $600 inverter isn't exactly top tier. It isn't even middle of the road. I'm not sure there's anything cheaper.

 

[robot_zombie]

what BMS are you running? you could check its log for cell OVP events, or try setting the charge voltage low (eg. 3.4V per cell) which should limit OVP events if the pack is unbalanced but still see ~90+ % capacity

I had a similar issue with a pack - 15S3P, problems with the busbars between cells meant some cells were getting out of balance and causing repeat BMS OVP events, it did cause the DC voltage to spike under full sun conditions, lucky it didnt hurt the inverter !!

 

[Mattb4]

Here it is

Just a guess but having two additional charge controllers on the same DC circuit as your AIO could be creating the problem. Are the settings for charge identical among the 3 MPPT's that you have working? Also double check if each SCC is working properly.

 

[MisterSandals]

pair of parallel Renogy 100A/24V charge controllers

This is quite a bit of charging capability for a 24V 280Ah battery.
What arrays were hooked up to each of the SCCs?

among the 3 MPPT's that you have working?

3 different arrays?

And none of the MPPTs communicating with each other in any way?