Mpp solar 3024msxe stopped working

[BartC]

Hi,
After a cloudy day mpp solar 3024msxe stopped working. My set up of 4x350w 2s2p with 150ah 24v lifepo4 in my RV was working fine for best part of this year and now unit stopped charging. Solar array voltage stays around 75v. I've checked 2x 40a fuses in the main unit and I have the same readings 75v. I've chased those black and red cables to the next little square circuit board in the centre of the unit and I get 9.2v there.
Overall unit looks healthy without signs damage. Please see photo attached
Is there any other internal fuses which could be possibly blown?
Anyone had this issue before?
Many thanks

 

[snoobler]

You using an LFP battery with BMS and low voltage disconnect? If your battery has gone open circuit due to a BMS trip, the SCC may not be getting power.

 

[gnubie]

Can you check the battery voltage reported by the MPP and also with a multimeter on the battery posts? I'm assuming the MPP is actually working, just not charging. If it's not working, BMS cut off is likely so still post the voltage shown on the battery with a multimeter.

If it is low volt cut off you will need a way to gently put some power into the battery to get it to the point where the BMS turns the output back on again then you can reconnect the MPP and it should spring back to life. Please do not take the advice given on some other forums and dead drop a lead acid battery on the lithium battery. That won't end well. You could do it with a decent power resistor though, or any current limited power supply with a voltage limit around 25V.

Even a cheap PWM charger would be enough to bring it back to life and get enough charge into it to allow the MPP to start. You'd probably want to use just one panel from your array to do this though, 75Voc is a bit high for a '24V' pwm charger to handle.

 

[BartC]

Thank you guys for you reply.
System is back and running.
Different problem I'm having now is that today is "suicidal weather" in UK and I'm not getting enough sunlight and for the first time I've tried to use utility charger to top up our battery without a luck.
I'm getting voltage on terminals going in the unit but no charging takes place.
My settings are:
Charger source priority : SNU
Max utility current : 10a
I've found in the manual that:
"if inverter/charger working in battery mode or power saving mode only solar can charge battery."
Could this be a problem?
Ps
Sorry if this is a daft question but this is all new to me?