Hello,

Any *very* experienced repairing man of isolar SMLII 3.5kw 24V here?

I have a unit which works. But, it draws too much power from MPPT to charge battery.  It drawn about 70W from MPPT which goes nowhere except perhaps in some heat. MPPT circuit is entirely ok. Battery charger power transistors, drivers and pre-drivers are all good. 

However both charger transformers have quite high temperature (around 40C-50C) even when the battery charging current is small (below 5A).   I do not remember how it was the transformers temperature when the unit was new.

A short circuit occur between one PV string wire and protective ground. Before this incident I saw around 2300W from the PV string.  After the incident, the maximum MPPT input power  in the same solar conditions was around 1400W.  The PVs are ok, I have replaced the inverter with a 5.5kw one and have up to 2300w input.

Attached picture with the board. 

Thx.

 

 

Edited October 26, 20241 yr by rowesley

Ok, perhaps someone knows this board (year of manufacture 2021). I have attached pictures with SN, one direction predriver & driver. Any schematic of power section for Easun SML II available somewhere ?

I do not know why uploading correct images they are turned. Thx.

On 2024/10/26 at 6:45 PM, rowesley said:

Hello,

Any *very* experienced repairing man of isolar SMLII 3.5kw 24V here?

I have a unit which works. But, it draws too much power from MPPT to charge battery.  It drawn about 70W from MPPT which goes nowhere except perhaps in some heat. MPPT circuit is entirely ok. Battery charger power transistors, drivers and pre-drivers are all good. 

However both charger transformers have quite high temperature (around 40C-50C) even when the battery charging current is small (below 5A).   I do not remember how it was the transformers temperature when the unit was new.

A short circuit occur between one PV string wire and protective ground. Before this incident I saw around 2300W from the PV string.  After the incident, the maximum MPPT input power  in the same solar conditions was around 1400W.  The PVs are ok, I have replaced the inverter with a 5.5kw one and have up to 2300w input.

Attached picture with the board. 

Thx.

 

 

it is normal condition

On 2024/10/28 at 11:31 AM, rowesley said:

Ok, perhaps someone knows this board (year of manufacture 2021). I have attached pictures with SN, one direction predriver & driver. Any schematic of power section for Easun SML II available somewhere ?

I do not know why uploading correct images they are turned. Thx.

chang 2 smd 100 ohms with new

you see it its black