I just finished installing my multi and 280Ah of lifepo4 batteries with REC BMS. Everything else seems to work fine but I can't get multi to actually charge at 70A. It claims it's charging at 60-62A but when measuring with Fluke clamp meter it shows only ~50A flowing. Additionally my BMS shunt shows the exact same reading as fluke does so I'm betting that the Multiplus current measurement is nowhere near accurate...
How do I get the missing 20 amps of charging out of multi? That's quite a big drop from the expected value and increases significantly the charging time for a 280Ah bank..
I have the weak AC off, 70A set as the limit in the settings. Environmental temp is around 27-29C where batteries and multi are. Batteries were at around 70% when I started charging so they should be easily able to take the full 70A.
And to be clear the REC BMS is not communicating with Victron yet so that can't be the issue either.
Additional info as requested. Screenshots of the settings at the end of the message. During the screenshot I had set the device not to charge so I can make sure it's cooled and not doing anything for a while so when I flip the charging switch there can not be any issues with heat in the beginning at least. The environment is around 25C right now so even if it was slightly derating due to temp it should not be too many amps as per this doc https://www.victronenergy.gr/upload/documents/Output-rating-operating-temperature-and-efficiency.pdf
Multiplus firmware version 481 which should be the latest as no updates are available.
AC is grid AC right now so no limitations on that side.
Did a new test with no AC loads on at all and multiplus in charge only mode. Discharched the lithium battery to 30% so it's nowhere near full.
Voltage at victron end:13.5V
Voltage at battery terminals: 13.3V
Still Victron showing about 62A in victron connect but real amps about 52A. And victron is in bulk charge mode.
Additionally I'm able to easily pull 130amps from the batteries and with solar + multiplus able to charge at 80A. Smart solar MPTT has the same voltage levels as Multiplus as well. So definately seems that there's a problem with the multiplus...