Hi all

 

I have an RCT Axpert VmIII 5kW and a Pylontech UP5000 battery with coms to a PC running the MultiSIB software.

 

I am struggling to set the system up so it doesn't charge the battery past say 80%. It seems that the Axpert will always charge the battery if a charging source is available and charge all the way to 100%.

Is there a way to stop the Axpert from charging the battery while Utility/Solar is available when the SoC reaches a certain value?

 

Cheers

Wiggly Electron

I'm not aware of any. But lead acid batteries should always be charged to 100%, and LFP doesn't mind as long as you allow the voltage to relax to a suitable "float" value after being fully charged. Only NMC and the like should be charged mostly only to 80%; those are rare (but present) for solar energy systems.

Many thanks!

 

I'll just leave it to float at 51.4V in that case. (My bulk charging voltage is 52.5V)

 

Cheers

20 hours ago, Wiggly Electron said:

I'll just leave it to float at 51.4V in that case.

Presuming that your battery is 15S LFP, you could go as low as 50.3 V. That's the 15S equivalent of what I use every day.

Actually, the battery should be charged to 100% regularly in order to do balancing. The chemistry itself might not mind being charged lower, but the balancing circuit only works above a set voltage, so if you always stay below that voltage balancing never happens.

46 minutes ago, P1000 said:

Actually, the battery should be charged to 100% regularly in order to do balancing.

Sure. But the bulk voltage of 52.5 V should ensure that. Plenty of Pylontech users are using 52.5 V, so I presume that balancing is happening. Especially with overshoots past 52.5 V.

Thanks everyone!

 

Indeed, the Pylontech manual states that bulk charging should be done between 52.5V and 53.5V. I also recall someone stating on another topic that cell balancing kicks in 0.2V shy of 52.5V.

I have dropped my float charge to 51V and will experiment on how it behaves.

 

Cheers!