Hey guys. After setting up my Home Assistant integration, i realized that the voltage readings are pretty far out(about0. 7v)

Does anyone know if there's a calibration for this, if it's available on the 1KVA axpert, and if anyone done it successfully?

2 hours ago, Adagio said:

Does anyone know if there's a calibration for this,

Yes. Calibrating your inverter's battery voltage reading.

Quote

if it's available on the 1KVA axpert,

Ooh. I can't see why not, except that the processors in those tiny models is likely a small 8-bit unit, and they sometimes leave out less oft-used commands to save flash space.

Quote

and if anyone done it successfully?

I've done it on my 5 kVA Axpert MKS models.

I'm not 100% Sure but IIRC It was an ARM last time I had it open...

Thank you very much! I'll try it out and get back to you!

Yeah. I don't think that's working.

Inverter isn't responding with an ACK9

4 hours ago, Coulomb said:

Yes. Calibrating your inverter's battery voltage reading.

Ooh. I can't see why not, except that the processors in those tiny models is likely a small 8-bit unit, and they sometimes leave out less oft-used commands to save flash space.

I've done it on my 5 kVA Axpert MKS models.

What even is the + button next to quote...?

I kept pressing that instead of the actual quote button...

4 hours ago, Coulomb said:

Yes. Calibrating your inverter's battery voltage reading.

Ooh. I can't see why not, except that the processors in those tiny models is likely a small 8-bit unit, and they sometimes leave out less oft-used commands to save flash space.

I've done it on my 5 kVA Axpert MKS models.

I feel like a bit of a chop now, as I just registered an account there to ask there for advice, but just realised you are that coulomb that wrote the original article.

Anyway. As I stated that side, The inverter is echoing the command (I made sure local echo is off) but it's not sending the ACK message.

It does however respond with NACK when I accidentally sent gibberish.

9 hours ago, Adagio said:

What even is the + button next to quote...?

It's for quoting multiple pieces of text at once. I just ignore it, and if I need to quote more than one piece of text, I do it one at a time.

It must be for really expert posters, unlike me 😉

8 hours ago, Adagio said:

I feel like a bit of a chop now, as I just registered an account there to ask there for advice, but just realised you are that coulomb that wrote the original article.

I was vaguely aware that two people seemed to be having similar issues, but didn't connect the two.  I respond to a lot of posts, and find it hard to keep track of them all.

8 hours ago, Adagio said:

The inverter is echoing the command (I made sure local echo is off)

The inverter should not be echoing the command, unless that's an accidental feature of the very small models.

As I posted on AEVA, I think get simple commands like QMOD working first. It should respond with something like (B·· where B stands for Battery mode (it could be L for Line mode etc). The ·· represent the CRC characters, which could be anything: letters, digits, special characters, sometimes unprintable characters. QPIGS should respond with a long string of digits and spaces, starting with an open parenthesis, as all responses do, and of course two CRCs at the end.

Hi , my inverter is gave me a Rong reads

Like current discharging read 

I need to calibrate the battery discharge current

What is the commend i need?

On 2023/08/24 at 4:34 AM, alaba 678 said:

I need to calibrate the battery discharge current

What is the commend i need?

I'm not aware of any calibrating commands for any measurement other than battery voltage.

[ Edit: I have since remembered that there are PVA0 and PVA1 commands (I don't know the syntax, it's non trivial) for calibrating the PV voltage readings, at least for the case of 145 V max PV models (which have a separate processor that controls the solar charging).  Warning: sending PVA0 on its own will reset your calibration, so it's not wise to blindly experiment. ]

If you are sure that your current measurements are bad, all you can do is fiddle with the op-amp resistors to change the gain.

Though if the problem is inverter output current, then some models use a Hall effect device, which can get magnetised. There are discussions about how you might demagnetise that sensor, though I'm not aware of any confirmed successes with that approach.

Edited August 25, 20232 yr by Coulomb
Added sentence about PVA0 and PVA1.

the problem is :

the inverter display on hes screen that there is 2 amps(dc) form battery ,but in fact there is no cureent form battey ,all load's get power from solar panels

and when the inverter charge the battery in 20 amps in real ,but the display shows that is the charge cureent is 18 (rong info)

Remember that there is about 50 W (about 1 A for 5 kVA models) consumed by the inverter electronics. In some models, there is no AC power supply, so the battery will supply that loss, certainly when there is no PV power.

Your missing current is about twice this, but also remember that the battery current is estimated. There is no direct measurement of battery current. So it's not hard to believe that it's off by one amp.

There isn't much that can be done with this inexpensive hardware.

I added an extra sentence to my previous post, noting that PV voltage can somehow be calibrated.

I have the same problem with an iSolar SPR 1000 a clone similar with Sorotec Revo VP 12V 1k ( i mean wrong calibration). If you have more info about the subiect it could help me to find the guilty piece. First trouble is the PV current which is registered with about 19 A offset, so the inverter shows about 260W of solar charging even after the panels are disconected. This is the reason why the inverter never stops if it is offgrid and in absence of solar, and so it depletes the battery overnight. The fans also run at full speed. I don't see a shunt in the PWM charging circuit so it might be a hall device that is way offset.

Thanks in advance for any help.

perfidus

Some Axperts measure current with a shunt and op-amp, and some use a Hall effect device. With a clone, it could be either. They might copy the Axpert circuit in either case, so it might be worth checking traced schematics for those to see if any seem to line up. 

Ahem. Of course, the discharge  battery current is also showing wrong. May I take this as a coincidence or is something wrong with a common piece of hardware?

In the photo attached i hooked a 40w load and the battery meter shows almost exactly 43W (3,66 A ) and inverter reads the load as only 1 Amp. The power scale indicates 0W / 0%. 

Where  do i find those traced schematics from Axpert devices?

Thanks for help

 

Edit: with a larger load it shows the right current and wattage (10 amps approx and 120W power from battery with 100W load ) so only in the lower range indication is non linear. Good to know!!

Edited October 19, 20241 yr by Perfidus

I note that Axperts (all models, as far as I know) do not have a direct battery current measurement. Instead they calculate/infer/guess it by other measurements, and making various assumptions/guesses for losses. So it's not too surprising to see that the accuracy goes up with larger loads.

23 hours ago, Perfidus said:

Where  do i find those traced schematics from Axpert devices?

The  same place you find all the best information for Axperts 😎: Pip inverter repairs and hardware modifications. There are contributions from many people from all over the world, including a few from yours truly. The above link goes straight to the schematics  index, but there are sections for repair, components, etc etc.

 

A few moments later😀:

I found that for PV current there is a shunt after all in this machine.

It has 4 resistors marked 2m0 and it's measurements goes to PWM board via opamp code U7. I'm almost sure now that those measurements are further calibrated in software, because on the OA output (pin 6) i found pretty consistent values in respect to real PV current ( measured by my lab power supply that simulates a solar panel. Now i have to guess the calibration procedure. 

It just appear to me: what if the op amp has his output drifted with exactly 1 Volt?  It should be easy to check replacing it with another one.

Normally if the inputs are tied to the shunt ends, which are at (PV-) 0V, with 100ohm series resistors, the output should be also around 0V with zero PV current... I will go back and trace schematic around this LM308.

Edit: actually the output could be offset with a reference voltage in the feedback network so until I trace the schematic I don't know.

Edited October 21, 20241 yr by Perfidus
back to school

Update: 

Output offset is the result of bad choice for opamp, with large figures for input offset voltage. Because of the gain setting in the OA, 10kohm/100ohm =100x, 10mV of input offset = 1 V output shift.

Tested with some improvised compensation circuit, and managed to pull the output of U7 to zero voltage, for the DSP to think that it has zero PV current. The fans stopped, and after 15 minutes the PWM circuit deactivated (no more back feed of battery voltage into solar panels) and "PV charging" with current drain for battery clearly stopped, putting the inverter to OFF, so the firmware does its job properly.

Now I order a new op-amp,  I selected OPA228 from TI, with 10uV input offset voltage and optional external offset adjust inputs.

Edited October 25, 20241 yr by Perfidus

Problem solved as expected, with new OpAmp with compensation terminals, and adjusting offset on the current transducer on board with the coulombmeter. I'm dissapointed by technical  support of the Sorotec and Easun, nobody answer to my emails.

Anyway, going to the forums was a big idea as I learnt a lot about this type of solar chargers/inverters.

Cheers!