Good afternoon all, did anyone perhaps experience something similar on these units? Axpert king/Kodak . I have replaced the control board and tested each individual component that the 27 page service manual guides us on.

Voltage shows 32.5 , and not the usual higher voltage which is confusing. I have another pcb which is completely dead .. I also don't see a fault on it , unless there's a processor somewhere which I didn't locate and probably can't test or replace .

On 2025/07/11 at 8:12 PM, Bas84 said:

I have replaced the control board

What firmware version does the replacement control board have? It's acting as if it is running 24V firmware on a 48V inverter.

But if the replacement control board firmware is good, then the battery voltage sense resistors are likely faulty. But it's strange showing a high battery voltage fault code when the battery voltage is reading so low.

It's definitely a weird one, the original control card works fine on another axpert king /kodak , tried two control boards on this main board and error 3 persists. I havent checked firmware, will do so today .I could just not figure out how it's displaying under voltage with an overvoltage code.

16 hours ago, Bas84 said:

I could just not figure out how it's displaying under voltage with an overvoltage code.

Well, if the new control board is for a 24 V model, then the firmware will assume that this inverter has lower value resistors in its battery voltage measurement circuit. So 3.3 V at the analog input port implies 32.5 V instead of 65.0 V (for example). Or maybe say 3.0 V means 32.5 V on a 24 V model, but say 53.5 V on a 48 V model, as there is possibly nothing wrong with the measurement resistors.

Unlike some other models, Kings assume a fixed voltage for each firmware; they don't "auto sense" the battery voltage.

Hi all,

Apologies for resurrecting an old post, but I am having the same issue as described here and there wasn't a clear fix/outcome.

The inverter and battery were turned off after the recent widespread power failure in PE, and after turning it on it displays the F03 (battery overvoltage) error before shutting down. The battery voltage on the display reads 32.5v, which is odd due to the fact that this is a 48v unit. I have confirmed that the battery is at 48.1v.

Any help would be appreciated.

The axperts can throw odd errors if the SPS capacitors, in particluar the ones on the -12V rail have failed. It's worth replacing all the SPS capacitors if you can.

I have seen the output IGBTs fail when trying to invert under the high voltage however they test fine in circuit and using a multimeter. Maybe there is a similar situation here and they are dragging the battery into protection mode and triggering F03 and the battery protection resets when you measure the battery? Here's a link showing this situation https://powerforum.co.za/topic/14666-repair-of-axpert-inverters-a-journey-started/page/27/#findComment-214451

On 2026/01/26 at 7:18 PM, Livid said:

after turning it on it displays the F03 (battery overvoltage) error

That's what the user manual says. But a quick scan of one of the King 1 firmwares seems (at a quick glance) to be associated with battery under voltage. If so, that would explain the fault code with such a low battery voltage reading. Unfortunately, at present I don't have the time to investigate fully.

So then it's a matter of why the battery voltage is reading so low. It could be one or more of the battery voltage sense resistors going high value. These high value SMD resistors subject to moderate voltage for long periods of time seem to fail more often than average.

If it's the -12 V rail, then that would affect many readings. Do other readings seem reasonable?

Edited January 28Jan 28 by Coulomb

This defect occurs for several reasons, mainly due to the paths in the fuse area which can be interrupted if the fuse heats up for certain reasons (poor quality or the nuts are not tightened properly). The same defect but followed by other error codes can occur due to the SPS source where there are devalued capacitors and especially the failure of the -12V stabilizer (LM7912)

I had the same problem since october 2025 with a VMIII Twin 4k.

inverter still without smart fan control. Impossible to start up. always error F03.

In reality batterie was at 26.2 Volt but the inverter was reading at 42 V. I openend the inverter serveral times, controlled most of the electronic parts, but nothing to find.

Finally I discovered the problem disappeared when dry sunny weather and came back as soon as humidity was increasing. I dissambled the inverter completly and found in different area's wet particals ( wet fine dust ) under small resistances. I cleaned the motherboard and threated with non-conductive spray. Now it works again without problem ( since end of december ) even in very cold and wet weather.

Now I will also try to replace the firmware with smart fan control firmware. My actual is U1 : 56 09 and U2 : 25 06. I see there were already lot's of discussions on this platform about what should be the best version .. But not easy to see the forest through the trees. Lot's of firmware versions have been reviewed. What should be the best version for me ? I am looking only for a good smart fan control.

thank you in advance for your advice

kind regards

i

On 2026/02/08 at 8:32 PM, Palawan said:

My actual is U1 : 56 09 and U2 : 25 06. I see there were already lot's of discussions on this platform about what should be the best version .. But not easy to see the forest through the trees. Lot's of firmware versions have been reviewed. What should be the best version for me ? I am looking only for a good smart fan control.

I don't own a VM model, but it seems that VM III and VM IV firmwares, at least for the 4kW and 6kW models, are interchangeable. The following post suggests that version 70.00 has good fan support, at least for a VM IV Twin:

Thank you for your reply.

I will try to upgrade with this version 70.00. I keep you informed

Kind regards