Hello guys, 

I'm new around here and I've been reading the forum for a while now.

Sorry If my English is not perfect. 

I'm building my own house, and I am completely off grid therefore 100% dependent on my solar system. 

That beeing said I have 8 x 545w panels 

Axpert max 7200 inverter 

8x 250ah batterys

Hyunday diesel generator as backup. 

 

What is happening to me is that in order for the automatic startup of the generator works, the inverter have to be in SBU mode. 

 

But in SBU mode the charging of the batteries work very bad, or don't work at all which cause the generator to stay on for long periods. 

 

If I set USB mode, the charging works as it should which is set to 30A for utility, but the auto start doesn't... 

Same applies to SUB. 

I've read in the forum that it might be a firmware related issue but I am kind of scared to update it because me and my family, we are completely dependent on the system and I'm afraid I mess something up. 

 

Can anyone point me or guide me the right way? 

 

Firmware version 45.07

Firmware version 2 12.06

Thank you in advance, if I can update something that can help you to help me let me know. 

What point on the inverter do you use to start and stop the generator?

Hey Scorp, 

I use the dry contact on the NO position.

In SBU mode it starts and stops with no issues there... 

 

I have it set like this 

Back to grid 46V

Back to batteries 51v

 

Today generator started at around 7h30 am, no battery charging at all. 

SBU mode 

Solar and utility selected as charging option 

 

 

Hello guys, can anyone lead me in the right direction? Tonight was tough... Affffr 😪

The dry contact is supposed to behave differently under different output source priorities:

In SBU mode, it turns on when the battery voltage falls below the value in setting 12.

In other modes, it seems to turn on when the battery voltage falls below the "low DC warning voltage", which might mean the point where the low battery warning is lit. For earlier models, this was 2.0 V above the low DC cutoff setting (setting 29). It still seems to be true, based on a quick check of Max 7.2 kW firmware version 45.07.

Would it be possible to make these two conditions the same? In other words, change setting 29 to be 2.0 V below setting 12. This all assumes battery type USE; otherwise, various constants come into the low battery voltage condition, based on percentage of load.

On 2022/02/11 at 11:14 AM, G0odGOD said:

Hello guys, can anyone lead me in the right direction? Tonight was tough... Affffr 😪

This is if you do not have a grid connection.

Start genny manual after the 230V is properly connected to the AC input. Run genny to be stable. Ensure all loads are switched off. When it does charge the batteries you can add a few loads say below 500W just as a test.

Once we know the inverter does charge one can get back to the start and stop via the relays in the inverter.

How about setting inverter setting 01 to UTIL. This will force the batteries to be kept full or as per settings.

Setting 02 on say 20A just to check if it would charge.

Setting 03 on APL

Setting 04 SDS

Setting 05 set to USE

Setting 09 to 50Hz

Setting 11 on 20A

Setting 13 on 52V

Setting 16 on CUt

Setting 25 on FEn

Setting 26 on 55.5V

Setting 27 on 53V

Setting 29 on 48V

Setting 32 on AUt

These numbers are as per my older Axpert. I hope they are the same. These settings are just to try and get the inverter to at least charge and if it charges then one can revisit them.

Reply and give an update.

 

On 2022/02/11 at 1:26 PM, Coulomb said:

The dry contact is supposed to behave differently under different output source priorities:

In SBU mode, it turns on when the battery voltage falls below the value in setting 12.

In other modes, it seems to turn on when the battery voltage falls below the "low DC warning voltage", which might mean the point where the low battery warning is lit. For earlier models, this was 2.0 V above the low DC cutoff setting (setting 29). It still seems to be true, based on a quick check of Max 7.2 kW firmware version 45.07.

Would it be possible to make these two conditions the same? In other words, change setting 29 to be 2.0 V below setting 12. This all assumes battery type USE; otherwise, various constants come into the low battery voltage condition, based on percentage of load.

Hello coulomb

I have AGM batteries and today I left it at USB mode and in fact it turned on at low DC warning which is 46v. Cutoff set to 44.

It turned off at around 51v. 

Set to 20amp charging with utility. 

At around 7am I heard the generator turning on and off several times for seconds and so I changed to SBU with the phone and it stopped. 

If I let it in SBU mode the batteries will take forever to start charging, the generator is working for nothing (for bypass like 200w or so) 

In USB it charges fast at 20 amp as set. 

So somehow I think we can use that USB mode and play with the battery settings whoever must figure out what's causing it to turn on and off several times for seconds. 

Also what I notice is that when only utility is charging the batteries, the battery voltage increase very fast, same happens when discharging. 

Thank you for your replies coulomb and Scorp