Hi everyone,

 

I have the above inverter, and it started misbehaving a few weeks ago with what seems to be "tripping" of sorts where the three led's beneath the display flickers all at once and I can hear some relays clicking on the inside of the box. This happens when it needs to convert DC to AC. I managed to get it to work again some time ago after the first time it happened by only switching on the solar panels and the batteries, no AC into the box, and it managed to recover itself after a while. After it recovered, I was able to switch on the "AC In", and it worked fine again, until tonight, when it went crazy after Eskom power went down, needless to say, it's not generating any output, and I had to switch it off completely.

Is there anyone that has knowledge of these inverters that can look at it and try and so some troubleshooting, perhaps repair if possible?

Any input will be greatly appreciated.

Johan

Can you post a side sticker pic. It will expose details like model number etc...

Also, what is the battery voltage doing during these spasms?

Preferably as seen with a multimeter.

What is your battery, and how old is it?

20 hours ago, Steve87 said:

Can you post a side sticker pic. It will expose details like model number etc...

Here is the model number

1 hour ago, Coulomb said:

Also, what is the battery voltage doing during these spasms?

Preferably as seen with a multimeter.

What is your battery, and how old is it?

The battery voltage is currently at 51.3v, and when the flickering happens, the voltage stays the same. I took a video but it's too big to load here.  I have 8 T105 6v Trojan batteries. They are about 7 years old, but I have taken good care of them. They are nearly due for replacement in any case. 

Edited June 21, 20224 yr by Johan Grobler
Additional information

On 2022/06/22 at 12:44 AM, Johan Grobler said:

The battery voltage is currently at 51.3v, and when the flickering happens, the voltage stays the same.

That's slightly over 12.8 V per 12 V module. If that's not being charged, that's quite full. Your post seems to be at 4:44pm your time, which at this time of year means the battery has probably just recently started discharging.

So that would appear to invalidate my theory that it's the battery voltage collapsing.

My next guess, especially given the age of the inverter (over 7 years) is  that some capacitors in the power supply are failing. There are posts about this sort of thing on the AEVA repair and hardware modifications topic. If you're good with electronics, search the index (in the first post). Otherwise, it seems it needs repair or replacement. It's getting harder to find these 145 V max Axpert MKS I models, but I believe they're still available (with increased specs: 5 kW output and 80 A MPPT).

Edit: the good news is that the schematic trace in that topic is from almost exactly the same model as yours, making diagnosis and repair easier.

Edited June 22, 20224 yr by Coulomb

2 hours ago, Coulomb said:

That's slightly over 12.8 V per 12 V module. If that's not being charged, that's quite full. Your post seems to be at 4:44pm your time, which at this time of year means the battery has probably just recently started discharging.

So that would appear to invalidate my theory that it's the battery voltage collapsing.

My next guess, especially given the age of the inverter (over 7 years) is  that some capacitors in the power supply are failing. There are posts about this sort of thing on the AEVA repair and hardware modifications topic. If you're good with electronics, search the index (in the first post). Otherwise, it seems it needs repair or replacement. It's getting harder to find these 145 V max Axpert MKS I models, but I believe they're still available (with increased specs: 5 kW output and 80 A MPPT).

Edit: the good news is that the schematic trace in that topic is from almost exactly the same model as yours, making diagnosis and repair easier.

Thank you very much for this response. I have done a lot of electronic work a few years ago and may just as well try and fix it myself, failure to do so, replace it, as I would in any case have to do that. I am in Cape Town, and it seems that there aren't anyone around here that can assist with repairs. 

4 hours ago, Coulomb said:

battery voltage collapsing

Now this has piqued my interest... I have had similar behavior from my inverter, but before it deteriorated to the stage of switching itself off with relays clicking I would get the normal fault beep with fault 03 [Battery voltage too high], at night about 2 hrs after dark which went against all my logic. Sometimes the screen would report the battery voltage at 120V which couldn't be right because they were all just under 13V when I measured them. I was told that it could be the gel batteries because when they get old the plates can warp and touch each other and cause a short... is this possible if I could restart the AC inverter using the switch at the bottom right of the box and everything would run fine through the night, just like Johan?

I ask this here because even though the battery voltage on the inverter was also around 51.3V, I have since done a load test on the batteries and I think they are indeed on their last legs, so it might be relevant... here are the readings, maybe someone can shed more light on things:

12.99V - at rest

12.03V - under load (washing machine at +-350W for 1hr)

12.61V - load removed

12.68V - rested for 2hrs

13.12V - after charge

I am concerned that under load, the battery voltage might be too low or collapsing as you say, even though the error I was getting was battery voltage too high [03], but I'm not sure if both together mean the batteries are toast. I know the rest voltage seems high, but from the manufacturers spec (Leoch) they are correct and very much the same as the Trojan T-105 specs too.

P.S. I have seen other errors since and my machine is now at the same stage as Johan's, but I'm wondering if it could have originated with the batteries or if it is simply the hot weather where I am that has slowly sucked the life out of it and the batteries are fine.

16 hours ago, jumper said:

12.99V - at rest

12.03V - under load (washing machine at +-350W for 1hr)

Those two readings say that the battery is high resistance. There is a small chance that it's wiring, weld splat on fuse, that sort of thing, but sadly, the most likely case is a very tired battery.

34 minutes ago, Coulomb said:

the most likely case is a very tired battery

Much appreciated, I figured they might be on their way out. I was told 3-4 years was normal for gel batteries where we are, I was expecting more. I was just wondering if you thought it would be possible for the batteries to cause a voltage spike like that and damage the inverter as I wanted to keep them as a backup for another 24V 3kva system I have running?

I will check all the wiring and connections to make sure everything is ok there, thanks.

I should have said, most likely your battery is very tired IF the voltages you quoted are real, e.g. from a trusted multimeter. But they can't be from the inverter, unless you divided by 4 each time. 

If the voltages quoted are real, then that doesn't explain the 120V readings, so there could be an inverter fault which could well have accelerated the battery's decline.

In a 24V system, the high resistance would not matter as much on the smaller system. I don't see how it would damage the inverter. As above, I'd guess it was actually the other way around (inverter damaged the battery). 

22 minutes ago, Coulomb said:

IF the voltages you quoted are real, e.g. from a trusted multimeter

I am using a cheap digital multimeter (I burned my expensive one on my electric fence lol) but it does give me 2 decimals if I read below 20V, so I tested the batteries individually.

 

25 minutes ago, Coulomb said:

so there could be an inverter fault....

...I'd guess it was actually the other way around (inverter damaged the battery).

Yes, thank you so much, this is what I am trying to narrow it down to and I think it has heat damage to the caps at C78 & C79 (swolen not burst) right at the top in the hottest part and I see in the service manual the battery voltage too high fault says possible damage to the reverse mosfets and TX9 (which is in the same area), so that might be a little too much for me with only a multimeter and soldering iron. I will investigate further and see if I can manage to fix it.

I really appreciate the feedback and all the work you and weber and co have put into helping us "voltronics" users, there is a wealth of information put together over many years and I've been reading as much as I can. Thanks.

On 2022/06/22 at 7:44 PM, Johan Grobler said:

I am in Cape Town, and it seems that there aren't anyone around here that can assist with repairs.

Hi Johan, I lived in CT years ago and when I had some damaged pcbs, I just went to the computer shop at Long Beach mall, found the guy doing soldering work and got him to replace the caps I'd sourced from rsonline, maybe you can try something like that.

Hi Johan,I've repaired many(hundreds) of those Axperts and their clones and yours sounds like a common fault.

Will be happy to assist you if you contact me.

 

Hi Johan,I've repaired many(hundreds) of those Axperts and their clones and yours sounds like a common fault.

Will be happy to assist you if you contact me.

Hi Peterj,

Where are you located?

I have the same problem with my Axpert. It started when the Eskom power was restored after load shedding one Sunday. The LED,s flicker on and off and I can hear a relay clicking. I disconnected everything except the battery but still the same. I opened it this weekend and looked for any obvious damage, nothing the eye could see. I even removed the SCC board, but still the same.

If someone could point me in the right direction I would appreciate it very much. I am a electronic technician and can do board level repairs.

 

Hi Peterj,

Where are you located?

I have the same problem with my Axpert. It started when the Eskom power was restored after load shedding one Sunday. The LED,s flicker on and off and I can hear a relay clicking. I disconnected everything except the battery but still the same. I opened it this weekend and looked for any obvious damage, nothing the eye could see. I even removed the SCC board, but still the same.

If someone could point me in the right direction I would appreciate it very much. I am a electronic technician and can do board level repairs.

Have a look  at my 'a journey started' thread on this forum. The fix is well documented. 

 

Have a look  at my 'a journey started' thread on this forum. The fix is well documented. 

Thanks for your reply. I see your tread, but it is lengthy. Any pointers where to look or what is the main causes for this problem.

 

Thanks for your reply. I see your tread, but it is lengthy. Any pointers where to look or what is the main causes for this problem.

Ok, here is a link below:

 

Be sure to click on the topmost title, otherwise it just takes you to the start of the thread. 

It is also important to replace the filter capacitor on the input of the-12v regulator. 

 

 

Thanks I will try that and let you know.

 

Ok, here is a link below:

 

Be sure to click on the topmost title, otherwise it just takes you to the start of the thread. 

It is also important to replace the filter capacitor on the input of the-12v regulator. 

 

 

Hi I replaced all the Capacitors with Hitano Low ESR capacitors and that solved the problem. I must still just test all the functions but all looks good so far.

Thanks for your help.

 

Hi I replaced all the Capacitors with Hitano Low ESR capacitors and that solved the problem. I must still just test all the functions but all looks good so far.

Thanks for your help.

Great. 

Is there a special way to test the SCC. I tried connecting a 53v power supply to the solar input with a battery connected to Battery input. I have a 30A fuse inline with the solar input. When I turned on the solar input PSU it want to start and I can hear a relay click but then the 30A fuse blew. I then put some high wattage resistors(1,5 ohm 25W) inline thinking that it has to do power point tracking but the resistors got hot and the voltage at the inverter input measures 0v. With the inverter off the solar input measures high resistance.

Does this mean SCC is faulty or am I testing wrong.

16 minutes ago, Henwilsch said:

Is there a special way to test the SCC. I tried connecting a 53v power supply to the solar input with a battery connected to Battery input. I have a 30A fuse inline with the solar input. When I turned on the solar input PSU it want to start and I can hear a relay click but then the 30A fuse blew. I then put some high wattage resistors(1,5 ohm 25W) inline thinking that it has to do power point tracking but the resistors got hot and the voltage at the inverter input measures 0v. With the inverter off the solar input measures high resistance.

Does this mean SCC is faulty or am I testing wrong.

I know very little about the MPPT. I do recall connecting a current limited supply to  check wether the DSP controller sees the value, but I never had the MPPT under load. 

@Coulomb might be able to assist.

If you disconnect the MPPT positive output cable to the main board battery connection BAT+, does it still draw current.? 

Edited October 8, 20232 yr by BritishRacingGreen

Thanks I will check that. @Coulomb any input? The battery is very small (5AHr) so it will not draw a lot of current.

SCCs are a bit tricky to test, because of the maximum power point tracking. I assume that this is a 145 V max PV type; I've never worked on a high PV voltage solar charger. These require serial commands and responses from the DSP to get them operating.

You didn't say if your 53 V power supply was current limited or not; it really needs to be current limited. Otherwise, the MPPT even if working properly will try to draw 60 or 80 amps from your power supply. I would initially limit the current to about 0.5 A, and try it at the power supply's maximum if all goes well.

Unfortunately, you really need a real battery (a small one should do, especially initially) for the SCC output. Otherwise, the charge current will have nowhere to go, and the output voltage will rise to silly levels, endangering other parts of the inverter. That's unless you have a special battery simulator test device, but those are unusual and expensive. That battery should have a DC rated fuse, because even a smallish battery is quite capable of blowing things up.

Using a resistor in series with a non current limited power supply is not ideal. As you have found, things get crazy hot very quickly. It might be possible with the right value resistor and a lot of heat sinking (like a bucket of water).

I've been lucky with my 145 V max SCC repairs; the only faults were fairly obvious like bad opto couplers preventing serial communication, and actually transistors on the control board at the other end of the serial comms cable. The actual switching part seems to be fairly robust; I don't seem to hear a lot about the MOSFETs failing.