I have a 75/15 connected to 2 x 40w solar panels in series which gives about 28v and 1-2amps charging current. When my 100ah lithium battery reaches full charge the controller cuts the load output and I have to reset it to get the lid the work again. I do this by covering the panels and removing the fuse.
I have checked all the connections and settings in the app but cannot understand what I am doing wrong?!
Likely the internal battery management system (BMS) inside the battery is saying it’s full, so it disconnects the input to prevent overcharging.
If you have a Cerbo GX (or Neo, or Ekrano) it can talk to some battery BMS systems and slow or stop the charging from an MPPT that has a VE.Direct connection. It depends if your battery has this capability (usually called a CAN BUS BMS connection).
If you have a SmartShunt it can be set up to monitor the state-of-charge of the battery, and it can be connected to a SmartSolar MPPT to monitor the voltage, and you may be able to use this to stop charging.
Buzzy,
Thank you very much. I can’t recall the brand of battery but it certainly has its own protection and is Bluetooth enabled. I will investigate along the lines you describe and perhaps I can get the two units to speak to each other over Bluetooth and I also have a number of data cables supplied with the battery I could try.
Clark,
Thank you very much for that tip. I have got it ‘always on’ as you suggest and it has turned off in that mode, I’m still not 100% what’s causing the switch off but I think most likely is it’s the battery doing it at full charge not the Victron - though it hasn’t happened the last time it cycled and I haven’t managed to research the battery settings fully. I will post when I get to the bottom of it.
Thinking that through, if the battery is turning off, then the solar controller would not have a supply.
The official line is that you should never have a Victron mppt device connected to PV but not to the battery as damage can occur. However, I have in the past inadvertantly disconnected the battery from the 100/30 with solar still connected in my campervan setup for several weeks, and it was fine!
Is your load directly connected to the battery or the mppt load output terminals? I had assumed the latter from your previous descriptions.
I think I’ve got it all wired up properly in that I’ve got the battery straight to the mppt and then the PV to the mppt as well so I agree with you. It seems strange that if the battery was turning off the mppt would not still have a source of power so perhaps that means that’s not the cause. There must be something else in the settings that I’ve got on the solar controller that’s causing it to cut off. Mystery! I’m sure it’s some simple mistake I have made.
