Sunny day here shining on my ~4000 W of solar connected to the SmartSolar (part of an EasySolar 5000) driving a pair of 48 V LFP batteries each with own BMS, linked together by RS485 and to the EasySolar by CAN..
The current to the batteries (as seen on the GX console and also in VRM) is oscillating rapidly between close to 4000 W and 0 W.
When I pull down the log spreadsheet from VRM, I can see Solar Charger [273] MPPT State changed suddenly at 11am (local which is +13h) from steady “MPPT active” to “Off”, then sometimes back to “MPPT Active” and “Off” again, at one point to “Voltage or current limited” and back to “Off”. These switches correlated with Solar Charger [273] Charge state toggling from “Ext Control” (by the BMS) to “Off”.
The battery charge (as reported via CAN) is only ~55% and the BMS is not using either Charge Voltage Limit or Charge Current Limit to throttle the charging. Neither Error or Alarm is reported any time during the hour of logging (and that includes no BMS alarms and no alarm to say “lost BMS”). The current draw on AC is fairly steady (charging an EV, with the help of a grid-tied inverter on the Multiplus’ AC Out).
Why would this happen? It’s the first time I have seen anything like this, despite having used this arrangement for several months now with excellent results.
would you please post the complete setting of your mppt , maybe then we can help you.
And, always my first idea : the mppt will work without any guidance from the battery, only regulating voltage and power. So disconnect the can connection and see what happens.
Are you using the EasySolar-II 48/5000/70-50 MPPT 250/100?
Or are you using (also) a smartsolar mppt?
Every time it shuts off, is when the panel voltage goes above 110v, so if you are using a Smartsolar 100x… then it’s the panel voltage that causes this problem.
If they are connected to the easysolar, then that shouldn’t be the problem.
Then maybe put some more vrm info in, like what battery SOC is at that moment.
Thanks @matthijsb It is just the EasySolar-II 48/5000/70-50 MPPT 250/100, no additional SmartSolar.
When this was occurring the battery SoC was about 55% and the batteries can absorb far more current than the system can deliver. So the problem should not be due to the battery shutting off.
I went to MPPT settings in VictronConnect. There is no generic “Lithium” preset, only “Smart Lithium (LiFePO4)” which is what I had. I tried to reset BMS control; it only worked when I was in Expert mode and had the CAN cable disconnected. Then, I was verifying the maximum charge current, charge voltage etc against the manual when the EasySolar made a grinding noise I never heard before and soon, shutdown (disconnecting all power supply to my home). I plugged the cable back in, the EasySolar gave some errors about low battery (it was 66% with around 2000W coming from the panels against my base load of ~400W) then finally sorted itself out again (telling me it is again BMS Controlled).
So, not sure how I can follow your advice re not using the CAN connection.
